2. TO OUR READERS IN THIS ISSUE
Wel come to StarTuned, t he
magazine for independent service
4 CLEAN STRAIGHT AND CLAMPED
tech nicians wo rking on Me rce des- One of the benefits of owning a Mercedes-Benz has always
Benz ve hicles . You r Merce des-Benz been longevity. But after many years of f lawless se rvice, there
dea ler sponso rs StarTuned and is a chance that head gasket failure wil l occur. The value of a
provides t he information com ing
Merce des-Benz makes it worth repairing.
your way in eac h issue .
Mercedes-Ben z wa nts to prese nt th e
12 AIC PRINCIPLES AND CONTROLS
inform ation you need to know to
Summer is almost upon us, and with th e warmer
diagnose and repair Mercedes-Benz
weather com e customers hot under the collar abou t
cars acc urate ly, qu ick ly and th e fi rst
air conditioning performance.
t ime; text, graphics, on-l ine and other
techn ica l sources co mbin e to make
thi s poss ible.
22 CUSHIONING THE BLOW - PART 1
Feature articles, derived fro m
As always, at Mercede s-Benz the top priority is t he safety of
approved company sources, foc us
the people who drive its vehicles . Airba g systems need to be
on be ing useful and interesting.
maintained and se rviced to ensure the same level of safety
Our digest of technica l inform ation
that the engineers intended.
can he lp you so lve unant icipated
prob lems quick ly and expert ly.
Our list of Me rcedes-Benz dea lers
can he lp you f ind Ge nuin e
28 SMALL REPAIR, BIG OPPORTUNITY
Merce des-Benz Parts . One of the benefits of owning a Me rcedes-Be nz is the
We want StarTunedto be both timeless style it exhibits. With bodies an d interiors sc ulpte d
helpfu l and info rmative, so please let like artwork , it's no wonder their owners ta ke pride in th em.
us know ju st what kinds of features
an d other diagnostic services yo u' d
like to see in it. We 'll continu e to 30 FACTORY SERVICE BULLETINS
bring you selected service bullet ins These suggestion s and solutions for technical problems are
from Mercedes-Benz and arti cles from service bull etins and other informatio n pub lished by
cove rin g th e different systems on Merced es-Benz, se lected and adapted for ind epen dent
th ese ve hicles. repair shops.
Send yo ur suggestions, questi ons
or comments to us at:
StarTuned
31 GENUINE MERCEDES-BENZ
One Me rcedes Drive PARTS ... NEARBY
Montva le, New Jersey 0 7645 Wherever you are in the United States, there's a nearby
Phone : 1 800 225 626 2, ext. 711 2 source of ge nuin e factory parts for your customers'
e-mail: StarTuned@mbusa.co m Merce des-Benz ve hicl es .
StarTuned is a quarterly publication of Mercedes-Benz USA, LLC ("MB USA") . No part o f t hi s news letter may be reproduced without the express written permission of
MBUSA. Editorial and Circulation Offices: 598 Pine Po int Dri ve, Akron, Oh io 44333. Caution: Vehicle servicing performed by untrained persons could resu l t i n ser ious
i njury to t h ose pe r sons o r others. Informat ion conta in ed in this news letter is intended for use by trained, profess ional auto repair technic i ans ONLY. Th is
information is p r ov i ded to i n form these techn i c i ans of condi ti o n s wh i c h may occu r in so me veh ic les or to provide info rmation which could assist
them in proper servic ing of these veh ic l es. Pro per ly tra in ed techn icians have the equipment, too ls, sa fety instruct ions, and know-how to perform repairs
correctly and sa fely. If a cond ition is described, DO NOT assume that a top ic covered in these pages automat ica ll y app li es to you r veh ic le or that you r vehicle has
that condition. StarTuned is a registered trademark of MBUSA .

3. STARTUNED
Information for the Independent Mercedes-Benz Service Professional
June 2008 U.S. $6.00 € 1
2.50 Volume 8 Number 2
Group Publisher Contributing Editor MBUSA Technical Production Manager
Christopher M. Ayers, Jr. Wade Nelson Content Advisor Devon Ayers
cayers@cmacomm.com wnelson@cmacomm.com Donald Rotolo dayers@cmacomm .com
Donald.Rotolo@mbusa.com
Senior Project Director Contributing Editor Circulation Manager
Tamra Ayers Kerry Jonnson MBUSA Project Manager Joann Turner
tayers@ cmacomm .com kjonnson@ cmacomm.com Russel l G. Chave j turner@cmacomm.com
Russe ll .Chave@mbusa .com
Editorial Director Contributing Editor List Consultant
Bob Freudenberger Ray Fisher Art Director NFocus
bfreud@cmacomm.com rayfisher@ cmacomm.com Jef Sturm
jsturm@ cmacomm.com

4. Clean, Straight
and Clamped:
Head Gasket Diagnosis
and Replacement

5. Aside from swapping an entire engine and/or
trans mission, rep lacing cy li nder head gaskets
is pro bably one of the more time-co nsuming job s
you perform. Looking at labor times, a typ ica l
cylinder head R&R procedure can ta ke 10 to 15
hours for a straight four or six, and up to 25
hours for a V8 or V12. The job represents a
sign ificant investment on the part of the
custome r. So, when yo u diagnose a failed head
gasket you need to be confident that this wil l
addre ss the customer's concerns. Some fa il ures
are straightforward, but on the more difficult
ones you need methods to ve rify your
suspi cions. Here, we' ll look at how head
gasket s fail , symptoms of fai lure, and foo lproof
testin g methods, and review some important
pro ced ura l points.
Pressure testing the cooling
system may force coola nt
through a leaking cylinder
head gasket. With a boro-
scope you can see into the
cylinder and observe if there
is any coolant seepage.
StarTuned 05

6. How Head Gaskets Fail
Head gasket failures can occur in several
different ways. The fluids that pass through the
gasket are either oi l or coolant. Pressurized oil is
sent through the gasket on its way to lubricate
the valve train. It then dra ins back through the
cyl inder head into the crankcase. Coolant also
passes through the cylinder head passages and
the block to keep these components cool. As
with any gasket, the one between the head and
the block is meant to sea l fluids in. The oil
pressure passing through the head and the oil
draining back to the block needs to be contained
by the gasket. Any externa l leak of oi l would be
considered a head gasket failure. By the same
token, any external coo lant leak would also be
a head gasket failure.
Not all leaks have to be external. The failures
that are not visible are often the ones that have
to be diagnosed. They require more in-depth
testing. Head gaskets may fail with the oil
pressure supp ly line breaching its gasket and
entering the coo ling passage . Oil pressure is
usual ly higher than cooling system pressure, so
oi l is forced into the cooling system. If the oil
return passage leaks, you may end up with
coolant in the crankcase. Another instance is
a high-pressure oil system leaks into the
combustion chamber.
Using a combustion gas Probably the most tel l-tale sign of a bad head
gasket is coo lant entering the combustion
leak detector will allow you chamber. This problem causes many symptoms
to determine if there's a leak from high pressure in the coo ling system
resu lt ing in blown hoses and leaks to steam
between the combustion exiting the exhaust. Techn icians naturally think
chamber and the cooling of th is situation first when head gasket failure is
mentioned, but as already mentioned this is not
system. Don't fo rget to drain the only type of failure. So, other than vis ible
some coolant out of the leaks or steam, what are the symptoms that
ind icate head gasket fa ilure?
system to build up sufficient
combustion gas. Tipoffs
We have discussed engine oil in the coolant
and coo lant in the oil. Another common-sense
item is the coo lant leve l. Very often we add
coo lant, check for external leaks and move on.
We ll , the coo lant had to go somewhere so
06 StarTuned

7. Here we can see the swirl marks left by surface
conditioning discs. If you stay in one portion of the cylinder
head too long you can create a dip that the head gasket
may not be able to seal. So, clean the cylinder head by
hand using suitable scrapers.
further investigation is warranted . Did an over- symptom. Combustion gases gettin g into the
heating problem cause the low coo lant cond iti on , coo lin g system can co llect at a hi gh point, and if
or did a low coo lant condition cause the it so happens that this is where the CTS (Coolant
overheating? Temperature Sensor) is located, the sensor may
Overheating is one of the major symptoms be exposed to gases instead of liq uid. This could
of head gasket issues, espec iall y if you do not cause the sensor to change its resistance value,
see any signs of external coo lant loss. If you hence its signa l, rapidly, and be an early
do have a leak, you may need to look deeper indication that somethin g is wrong with the
anyway. Sometimes a leak is just a leak, but coo ling system.
excess ive pressure in the coo lin g system w ill Fin all y, a driveab ility prob lem may be an issue
promote and en large leaks. Of course, there are that has more to do with engine temperature
many possible reasons for overheating, but it' s than the fuel inj ection and ignition systems.
always a good idea to test for head gasket fail - Cylin der misfires can be caused by coolant leak-
ure before (or even after) coo lin g system in g into a combust ion chamber. Mercedes-Benz
repa irs. After all, if the overheat in g was engin es are known around the world as some of
severe enough it may have warped the best, but lack of proper ma intenance, use of low-
cylinde r head casting(s) . octane fuels and long periods of time in stop and
If you r customer's concern is an erratic go traffic can contribute to premature failure of
temperature gauge, this may be another various components, such as the head gasket.
StarTuned 07

8. HEAD GASKETS
Testing, Testing, Testing, ... is a good idea to test under both cond it ions. A
head gasket may leak when cold, but not when
He re is where it may get ugly. You have a veh i-
hot, and the opposite is also true. If you pres-
cle come in that's running a little roughly. Maybe
sure test the system and get noticeable white
the Ma lfunction Indicator Lamp (M IL) is f lash ing,
"smoke" (actua ll y steam) out of the ta ilpipe, one
indicating a misfire, or there's a message in the
or more cylinders are leaking coolant into the
instrument clu ster message center indicating
combustion chamber. If you have a boroscope
that the PCM has detected a problem. You eva lu-
that allows you to look into the spark plug holes,
ate the service records and see that a tune-up
you may be able to actually see the leak while
may not have been performed in quite a whi le.
the system is pressurized. Using Star Diagnosis,
Maybe the customer has forgotten about the
or an approved scan tool, you can look at mis-
60,OOO-mile service, or has just been resetting
fire data. Th is may help indicate what cy linders
the "ASSYST" warn ing system, wh ich indicates
are the like ly cu lprits.
the need for ma intenance. Whatever the reason,
If the symptoms are minor, finding a head
you inform the customer that maintenance serv-
gasket leak will be more difficult. The best way to
ice is due , and you perform the tune-up. A con-
test for a sma ll compression leak is to use a
siderab le amount of money must be spent, but
"chemical block tester." This contains a chemical
this is a Mercedes-Benz and the customer clearly
solution in a mu ltiple diaphragm syringe. Gases
sees that the veh icle is worth the requ ired invest-
in the cool ing system are drawn into the tool and
ment. The problem occurs when the symptom
mixed with the solution. If combustion gases are
comes back. Now, your reputation is damaged,
present, these chemicals change color. To get an
and you have to dig a little deeper.
accurate read ing you need to dra in approximate-
You may have tested the coi l by check ing its
ly one ha lf to one fu ll ga ll on of coo lant from the
output with a spark tester (HE I type), or rep laced
system, depending on its tota l volume. This
it anyway. You could change the position of the
all ows a sufficient quantity of gases to bu ild up
co il (in coil-aver-p lug configurations) and see if
in the coo lant reservo ir and the radiator fo r the
the problem moves. If not, you may perform a
leak detector to work. Overlooking this step is
"fue l pressure drop" test on the injector and/or
likely to lead to fa lse readings and an erroneous
changed its location as well only to f ind the prob-
diagnosis.
lem is still in the same cylinder. Providing it is
not a defective new spark plug (what are the
odds of that?), the problem must be in the cy li n-
der. A compression test may indicate an accept- Now For the Hard Work
able amount of pressure, but a leak-down test
may te ll you a bit more. Low compression on two Once you have determined that coolant is
adjacent cyl inders typ ically means the gasket indeed getting into the combustion chamber, it's
between them has failed. Through a process of time to start the disassembly phase. At this point
elimination, you have determined all other it wou ld be wise to inform the customer that
components are performing as they shou ld, but although it looks like the head gasket has failed,
you still have a misfire. You need to look at the there cou ld be other causes such as a cracked
possibility of coo lant leaking into the block or cyli nde r head. There is no way of know-
combustion chamber. ing until disassemb ly has been completed and
Pressure testing the coo li ng system is a good the various components checked for cracks.
way to find leaks, inc luding leaks into the com- Depending on the age of the vehicle, this may
bustion chamber. Head gaskets survive also be an opportunity to renew various engine
admirab ly under tough condit ions. They need to components. The cylinder heads themse lves
seal when the engine is both co ld and hot. So, it could be exchanged for units refurbished by
08 StarTuned

9. After cleaning, measure the surface straightness of the cylinder head mating
surface. In this case it was necessary to mill the cylinder head, and the head
thickness was sufficient to do so. This creates a near ideal surface fo r the head
gasket to seal against.
Getting Cleaned Up
Mercedes-Benz. If you are equipped to rebuild
the cyl in der heads, you can perform the task Clean in g the cy lind er head gasket surface
yourse lf. Even if you do not have the equipment properly is critica l. Aluminum is so soft, it' s easy
to cut the val ves and va lve seats, you can to ruin a head casting with electri c or pneumatic
remove t he va lves and lap them in . Cylind er head tools in a matter of seconds. Do not use Scotch
gasket sets typically include va lve guide seals, so Brite pads on yo ur "whizzer" too l as they will
replace them by all means. Timin g chains need cause gouges and undulations, and leave
to be removed in order to perform the head abrasives behind that can actua ll y damage bear-
gasket j ob, so a new tensioner wou ld be a good in gs. Ditto for the sea ling surface of the block.
idea. Replacing the timing chain itse lf wo uld be Soak in g the head in a distillate so luti on causes
advantageous from a labor saving standpo int. the gasket remnants to soften for easier rem ova l.
After removing t he t imin g chain, and the intake The use of a properly sha rpened gasket scraper,
and exhaust systems, (sometimes it's easier to free of gouges itself, wi ll remove most of the
remove the cylinder head wit h the exha ust material left on the head.
and/or intake manifolds sti ll attached), we can Next, acc urate measurements must be taken
then unscrew the head bolts. With aluminum for surface flatness and irregularities. Th ese
cylinder heads, Mercedes-Benz recommends that measurements, along wit h t he overa ll t hickness
you crack each bolt loose in four stages of about of the cy lind er head, will determine if the casting,
90 deg. each. Thi s prevents any warp in g of the sim ply needs to be clea ned, or must be mill ed or
head, espec ially on a warm motor. Once the replaced. Hold a straight edge tool against th e
bolts are out, t he castin g is still "glu ed" to the block and cylin der head in multiple positions and
block by the sea l of the head gasket. You need to measure the depth of any gaps with a feeler
find a safe point to pry the cylin der head from gauge. If excessive "waves" or "rippl es" are
t he block, th en yo u can safe ly lift off the cyl ind er found, t he head or block must be milled to
head assembly. assure a good sea l.
StarTuned 09

10. HEAD GASKETS
Look at the two cylinder head
bolt holes on this 190 model
and you can see that the one
on the lower right is cleaner
than the one on the left. Do not
use a tap to clean bolt hole
threads. You will remove too
much material. Use thread
cleaners or chasers and you will
have a secure mating of the
thread surfaces.
You should also be concerned with the head www.startekinfo.com) document AH01.30-P-
bo lts. Since torque-to-yield bolts are used 1000-0 6V, there are two different dimensions in
(mean in g they stretch), Mercedes-Benz has the compress ion rin g of the cylin der head gasket
included a spec ification on head bolt length. for the 11 2 and 11 3 engines found in the 210
If the head bolt has stretched beyond th is spec, chass is. Th ey are distinguished by one or two
then the possibility exists that th e bo lt will notches found on the outside of the timing chain
bottom out in the block and the head bolt will passage of the gasket. If the smaller dimen sion
not apply the necessary clamp ing force to the is used in th e larger application the piston may
cylinder head allowing it to wa rp when the contact the gasket and create a knocking noise
engine gets up to operating temperature . Or, at idle. Does the aftermarket head gasket
th e bo lt may simply snap, wh ich wou ld resu lt in supp li er make th is distinction?
a time-consuming extraction job. After returning any dowels to the engine block
that were removed for cleaning, locate the head
gasket properly and carefully lower the cy linder
Reassembly head into place. Of course, the cylinder head
bolts must have the proper torque applied in
Now is the time to choose what kind of four stages to ensure the casting is pul led down
gasket you 're going to use to reassemb le the evenly and the gasket receives uniform clamping
engine. Remember, genuine Mercedes-Benz force. Fo ll ow the published service procedure
replacement parts use the same design, materi- carefu ll y. Th e same process applies to any other
als and construction as the origina l - and look large gasket surfa ce such as the intake and
how long it lasted . The cost is competiti ve with exhaust manifold s. Insta ll the timing chain
aftermarket brands that simply can't come up to accord ing to service procedures outlined in WIS.
Me rcedes-Benz standards . Thi s is not a job you Rotate the cranks haft a few times to verify that
want to do over again. the tim ing chain is instal led properly.
Acco rding to Mercedes-Benz WIS-net Yo u can fin ally co nnect auxi li ary devices and
(accessib le through a pa id subscription to components, fill with fluid s and check for leaks.
0 StarTuned

11. Enticingly graceful and dynamic.
Strong support, too.
QUALITY FIT PERFORMANCE VALUE SERVICE
WARRANTY
EllelY part comes with lhe reassurance
of a siron;; 12·monlh/unlimiled·milea!?11
limitlli/ l1'armnty - with (I(/diliurw/ wVI!mge
for en;;ines and transmissions:
Unlike any other.
The part is just part of the story. The precise fit and superior performance of a Genuine Mercedes-Benz
Part is a given. But equally important is that each Genuine Mercedes-Benz Part - down to the last nut,
bolt and gasket - comes with the unmatched technical support and expertise from your dealer and
Mercedes-Benz. All evidence of our constant dedication to supporting your business in more and better
ways than anyone else. And that's the best part Visit mbwholesaleparts.com or contact your dealer. Mercedes-Benz
•StlR. your Mercedes-Benz denier rortl~((JiL~ anti (l ropy t){cllB 11IIeJr.(>.(Ie..:rBenz Replacement PafL<i Llm[w..t} l-I'tlflYllUY.

12. FEATURE ARTICLE
Ale Principles a
2 StarTuned

13. nd Controls
Summer is almost upon us, and with the warmer
weather come customers hot under the col/ar about
air conditioning performance.
Advancements in technology are everywhere. temperature of the refrigerant is increased as we ll .
From computer-controlled systems to new This hot pressurized gas is sent to another
materia ls, the automotive industry is march ing component cal led the condenser. The function
forward to provide lower em issions, increased of the condenser is just that. It functions like a
safety and more creature comforts. The creature radiator - air flows over its fins and tubes
comfort in question here is Automatic Air cooling the contents. As the refrigerant cools it
Conditioning (AAC), which provides more condenses into a high pressure liquid and exits
efficient cool ing of the cabin. Driver, passenger, the condenser. The refrigerant then passes
and even rear passengers (Thermotron ic) can through what is ca ll ed a receiver Idryer. This
each enjoy their own persona l space, at least component filters out impurities in the refrigerant
when it comes to temperature regu lation. charge, both chemica l and physica l debris.
As a technician you may feel these advance- The next component this high pressure liquid
ments come at the price of added complexity in passes through is, in the case of Mercedes-Benz
diagnosis and difficulty of service, but this is vehicles, an expansion valve. Its job is to meter
not entirely true. Yes, the systems are more the liquid through an orifice, forming a low-pres-
compl icated, but the basic princ iples of air sure liqu id. This low-pressure liquid now enters
cond itioning still apply. All you need to know is the evaporator core. Th is is where refrigeration
how the advancements improve system actua lly takes place. As the low pressure liqu id
operation and take them into account, passes through the evaporator core it changes
particularly during troubleshooting. state and absorbs the heat in the air around it.
A blower motor forces either fresh air from
Basics outside the car, or recirculated air within the
cabin, through the evaporator core and the core
In order to understand the changes in air absorbs the heat in the air. It's sort of like a
conditioning systems over the past few years we radiator, but it works backwards. Instead of the
first need to have an understanding of the most heat of a liqu id being dissipated into the
basic principles. We will start with what is consid- airstream, it's the other way around. As the
ered the heart of the air cond ition ing system, the low-pressure liqu id absorbs the heat of the cabin
AIC compressor. Its function is to take the it evaporates and becomes a low-pressure gas.
mechanical energy of a runn ing engine and con- Th is passes back through the expansion valve,
vert it into a pumping action that moves refriger- giving the expans ion valve an ind ication as to
ant throughout a closed system. It takes in a low how much heat is being absorbed (load) and
pressure gas and pressurizes it into a high pres- opens and closes the va lve accordingly. Finally,
sure gas. During this process, due to the compres- the low-pressure gas is returned to the compres-
sion of the gas and the friction created, the sor and the process begins allover again .
StarTuned 13

14. AIR CONDITIONING
Automatic Air Conditioning (AAC)
The purpose of AAC is to control temp erature
and direction of airflow accord in g to th e occ u-
pants' desires . Thi s is accomp li shed by using
compute r contro ls to monito r ca bin co nd itio ns
and outside temperatures, and to provide t he
changes requ ired to respond to occ upant
requests. Let's look at th e t yp ica l players
involved in this symphony of cli ma te co ntro l.
The first component we wi ll discuss is the
climate control computer. This is the brain of the
system, both mon itoring input and ma nipulatin g
outputs to respond to the passenge rs' needs .
The contro l un it can be on its own, or, in t he
case of most Mercedes-Benz veh icles, can be
inco rporated into the co nt rol panel in the veh icle.
Se lf-d iagnostic fu ncti ons have also been in co rpo-
rated in their des ign.
Next on our list are t he enviro nmental senso rs. By positioning the driver's side temp to
These relay information back to the com puter.
They indicate air tem peratu re outs ide the ve hicle, high, the passenger side to low and
inside the ve hi cle (in the case of dua l zo ne pressing the "ECON" and "REST" but-
climate control, the te mperat ure in bot h t he
driver's side and passenger's side ducts).
tons, you can have this AAC control unit
Mercedes-Benz has also in co rp orated a sun loa d display codes. You can also command
sensor that mon ito rs ambi ent su nlight and
adjusts air co ndition ing co ntrols to co mpensa te
output control and read sensor values.
for it. More input sensors are use d to co ntro l
bot h the A/C system and heating systems . A/C more temperature co ntrolled zo nes in t he
refrigerant switches/se nso rs are used to monitor ve hicle's inte ri or the more sensors and motors
refrigerant press ure and te mpera ture to co ntrol will be add ed, but the ir basic opera tio n will be
compressor operation, hence te mperat ure. As ide the sa me. Up until rece ntly most of these "mode
from read ing refrigera nt tempe rat ure and pres- door" contro ll ed outputs we re hand led with a
sure in the lines, there are also se nso rs that read system that used engine vacuum and redirected
the temperature of the evapo rator. Thi s tell s the it to va ri ous diaphragms under the dash,
contro l un it when the evaporator core is st artin g attac hed to th e HVAC control assembly, to
to freeze so the AAC unit can preve nt ice from cha nge airflow directi on. Th ese systems have
forming and blocking air flow. Add itional senso rs since bee n replaced with electric motors that
include a Multifunction sensor th at passes on co ntrol mode door operat ion. In the past a
humidity information to the AAC un it. mec han ica l leve r positi oned a doo r th at co n-
On the output side of t he eq uati on is th e t ro ll ed th e temperature by mixin g th e coo l air of
compressor clutch (not eve ry veh icle has one), the A/ C syste m with the hea ted air of t he heater
so lenoids and mode doo r motors. Th ese outp uts co re. With ACC, the co ntrol un it operates an
contro l when the compressor cyc les on and off, electric mot or blend door (or two , or more) in
how much heated coo lant will be all owe d into response to changes in sun light , ambi ent
the heater core and what vents th e airflow will te mp erature and occ upa nt request s. Th ese
be directed out of. As ment ioned ea rlier, th e motors also provid e feed back as to the ir position
1 StarTuned
4

15. With a paid subscription
to www.startel<info.com
you have access to facto-
ry wiring diagrams. In this
diagram for the S-C/ass
(220 chassis), 1001< at the
wiring for the left SAM. If
you follow the wire from
component N I0/6, you'll
see that it controls the
AIC Compressor Control
valve.
for diagnostic purposes. When repla cing these anywhere from 125 to 350psi. These pressures
motors or the AAC control unit you wi ll need a show the compressor is capab le of creating
factory scan tool, or equivalent, to ca librate the suction on the low side and generatin g high
motor positions. pressure on the high side .
What do we do when the A/C system perform-
PSI ance is not up to snuff? We check these pres-
sures. If the pressure of the high side gas is too
One of the most basic test s yo u ca n perform hi gh we suspect a restriction in the system. On
on the hardware of the A/C system is monitoring the high side, thi s can either be a clogged receiv-
the high and low sid e pressures . As we dis- er/dryer, or a stuck-closed expansion va lve . If
cussed earlier, the refrigerant system is broken the high side pressure is too low, then most like ly
down into four phases: high pressure gas, hi gh the expansion va lve is stuck in the open position.
pressure liquid, low pressure liquid and low pres- There are diagnostic flow charts provided by
sure gas . Monitoring these pressures will indicate Mercedes-Benz that outline the testing of basic
if the re is a problem in the system and where the pressures and the problem s associated with
prob lem may be. Typi cally, Schrader va lves are variou s readings . Th ese pressure charts have
conven iently mounted in th e air condit ioning been used for years on basic A/C systems.
lines on the hi gh- and low-pressure sid es of the In the mid-'90s Mercedes-Benz started to use
system. They allow you to mon itor the gas variabl e-d isplacement compressors. These use a
pressure in the system whi le it is operatin g. By moveable swash plate that ca n change the piston
monitoring both sid es of the system you can stroke trave l. Thus, in high lo ad cond itions the
usually get a good idea of what the performance displacement of the compressor can be
problem may be. We have al l been taught that increased and for low load situations it can be
with a proper refrigerant charge th e low side of decreased. Thi s allows greater contro l of
the system ca n be pulled down to 20 to 30psi. compressor load as the engine rpm changes in
The high side pressure will increase more respo nse to the drive r's demands. As a resu lt of
depending on ambient temperature and can run th is design change, yo u need to know the
StarTuned 15

16. AIR COND ITION ING
When looking for the
compressor in a wiring
diagram from the
www.startekinfo.com website,
you need to know that it will
be found in section 54
Electrical Systems -
Equipment and Instruments.
In the case of this 220 chas-
sis, the left Signal Acquisition
Module controls the Ale com-
pressor. Trace the wiring for
component A9.
position of the swash pla te if yo u are going to and AIC co mpresso r output. This is also how the
use pressures to determin e what is wro ng with co mpressor is shut off. Wi th t he contro l va lve at
the system. In additi on to knowin g the hi gh and 2%, it is wide open and the hi gh pressure
low side pressures, yo u will need to know th e red uces the piston stroke to ni l, eliminating
co mm and from the AAC co nt rol unit fo r t he co mpresso r output but stil l keeping t he internals
swash pl ate position . There is no feedback on lubri cated. If t he low side pressure goes above
swash pl ate position, so you wi ll j ust have to that of t he diaph ragm, the AIC Compressor
monitor the pressu re change relative to t he Contro l va lve is ope ned up to 100%. Th is al lows
command change by increasing AIC re quest the swash plate to move to a position increasing
through t he contro l pa nel (lowe rin g req ueste d piston stroke and ove rall pressu re in the high
AIC tempe ratures) . A so lenoid, ca lled the AI C side of th e system . So, ba sica lly low side
Compre ssor Control Va lve, indirectly co ntro ls th e press ure and th e AI C Compressor Contro l va lve
position of the swash pl ate . Let's see how this co nt rol th e pressure in the case and t he position
is done . of the swas h plate, and ulti mately th e out put of
The AI C Compressor Co ntro l valve has a pre- the comp ressor.
pressurized diaphragm mounted in side t he valve Some com pressors still use a compressor
at just below 30psi. Thi s valve is connected to clutc h. The clutc h is mounted behi nd the pu lley.
the intake, or low pressure side of the compres- This is sti ll necessary to engage and disengage
sor. If the low side fa ll s below diap hragm pres- the co mpressor and is still a potential fa ul t, but
sure, the AIC Com presso r Contro l va lve is co nve ntional diagnosti cs preva il here. Check th e
commanded for a low openin g and ca n be as low amp draw of the clutc h, and li sten for noisy
as 2% (A/C off positi on) . Yo u can monito r t hi s co mp ressor engageme nt. Th ere is a TSB # P-B-
manua ll y with a DMM, or thro ugh your sca n too l. 83.55/87 that informs us how to bypass the
Th is valve position allows hi gh side pressure into compresso r with a sma ller serpentine belt. If the
th e compressor case. The pressure pushes th e noise goes away th ere is a problem with the AIC
swash plate in, thereby red ucin g piston stroke pul ley bearin g. Yo u ca n replace the front clutch
1 StarTuned
6

17. The AIC Compressor Control valve is On vehicles with this compressor pulley,
pictured here as component # I . This you will definitely have on AIC
valve controls the pressure applied to Compressor Control valve to tum the
the case of the AIC compressor. compressor on and off. If the
On vehicles without on AIC clutch, compressor seizes, the outer pulley
this is how the compressor is turned separates from the inner pulley, thus
on and off. saving the belt.
and bea ring assembly in the veh icle, so you do simple. On singl e clim ate zone systems with the
not have to remove the compressor. Th at's a ign iti on key on, you set the temperature to " LO"
relief since this compressor is one of the harder and within 20 seconds apply the "REST" and
ones to R& R. A/C compressors that do not use defrost buttons at the same time. Th e LED in the
a compressor clutch use a rubber couplin g. rec ircu lation button will flash and the liquid
crysta l display shou ld show "diA". Now press the
"AUTO" button and a code will be displayed if
Self-Diagnostics? one has been set. Push the "AUTO" button again
and you will adva nce to the next code. Apply the
Not only has Mercedes-Benz incorporated a "AUTO" button aga in until the codes start to
self-diagnostic function into its AAC systems, but repeat. To clear the codes, use the tempe rature
you do not need a scan tool to access them . arrow up and arrow down button simultaneously
Th e contro l panel of the AAC system is the and hold them down for more than five seconds.
technici an interface. This rule applies from the In the event that you do not want to erase the
early '90s into the late '90s. Otherwise, Star codes, you can apply the "AUTO" button and the
Diagnosis, or its equiva lent will be required . If faults will not be cleared. Shutting the key off will
yo u are between these years, the process is end se lf-diagnostics .
(Continued on page 20)
StarTuned 17

18. Replace - We replace more parts than aftermarket brands.
Engineered - Designed to meet original OEM drawings.
Manufactured - Made with same DE components as factory parts.
Assembled - Completely assembled from components and not just repaired .
Improved Technician Efficiency

19. 260E 1987-1989
300CE 1988-1993 INTRODUCING: NEW APPLICATIONS
300EITE 1986-1993
3005E1 5EL 1988-1991
3005L 1990-1993
PART NUMBER MODELS YEAR
A 0002300511 80 35050 1991 C240/C320/S430
35050L 1990-1991 AOOO 230 91 11 80 S500/CL500/CLK320
2004
E320 1994-1995
5L320 1994-1997 E320/E500 2003·2006
5L600 1996-1997 A001 2301211 80
CLS500 2006~
400El500E 1992-1993
5005L 1990-1993 ML350/ML500/ML55AMG 2003~
A 00023006 11 80 E420 1994-1995 A001 23028 11 80
E500 1994 G500/G55 2003+
5L500 1994-1999
A001 230 68 11 80 ML320/ML430 UP TO 2000
1900 1986-1989
1900T/3000TI TOT 1987 S55AMG/CL55AMG 2003-2005
190E 1985-1993
AOOO 230 90 11 80 C240/C320 UPTO 2003
260E 1987-1989
300CE 1988-1989 CLK320 2003
A 000 230 1111 80 3000 1987-1993
300E 1986-1992 AOOO 230 78 11 80 C32AMG KOMPRESSOR 2002-2004
300SE 1988-1992
300SEUTE 1988-1991 C230K M271
E3000 1995
AOOO 230 97 11 80 (VIN RANGE SPECIFIC)
2004
C2201 C280 1994-1995 S600/CL600 2001+
A 000230 1311 80 C36AMG 1995 A001 2300111 80
S65AMG/CL65AMG 2005+
300S0 1992-1993
E55AMG 2004-2006
300SEI 600SEC 1993
600SEL 1992-1993 CLS55AMG 2006
A 000230171180 5320/53500 1994-1995
5420 1997-1999 A001 2301411 80 E350/E5S0 2007
S600 1994-1996
CLS550 2007
CL600 1998-1999
5320 1995-1999 E320CDI 2005-2006
A 000230 2211 80 S3500 1995
CLK550 2007
S600 1996-1999
CLK55AMG 2003+
1900 1986-1989
1900T/30001 OTI TDT 1987
A001 23019 11 80
SLK55AMG 2005~
190E 1985-1993
260E 1987-1989 C55AMG 2005+
A 0002302411 80 300CE 1988-1989
300E 1986-1992 2004
300SE 1988-1992
30050L 1986-1987
300SEUTE 1988-1991
4205EU 5605ECI 5EL 1986-1991
A 0002302511 80 5605L 1986-1989
400SE 1992
4005EU 5005EC 1993
A 119 230 00 11 80 500SEL 1992-1993
5420/500 1994-1995
C280/C43 AMG 19911-2000
CLK320 19911-2003
CLK430 1999-2003
CLK55 AMG/ML320 2001-2002
A 00023070 11 80 E320 19911-2002
E430/E55 AMG 2000-2002
ML430 199~2001
ML55AMG 2000
5LK230/5LK320 2001-2004
CL500 2001-2003
CL55AMG 2001-2002
A 001 230 0211 80 5430 2002-2003
5500 2002-2003
S55AMG 2002-2003

20. On dual zone systems, it is sl ightl y different. Here is a Duo-Valve assembly for dual
With the key on make su re the driver's sid e tem-
perature is set to " HI" and th e passenger side is zone climate control systems. This
set to "LO". Within 20 seconds press th e "REST" valve is normally open (defaults to full
and "EC" buttons together and hold them down
for over five seconds. The display will indicate
heat if there is a failure) and the AAC
"d i R", the LED in the recircu lation button will control unit grounds it to close it dur-
blink and once again pressing the "AU TO" button
on the passenger side wi ll advance you through
ing AIC operation. Make sure these
any stored trouble codes. The letter "E" is dis- valves are closing when AIC is
played on the left side of the LCD and the code
on the right. Hitting the "AUTO" and the arrow
requested.
button to increase fan speed for two seconds will
clear the codes and "FF" wi ll be displayed on the temperature sensors should change their signa l
screen. Pressing the "AUTO" button at this point vo ltage when different temperatures are selected
also cance ls the code clear. Shutting the ign ition and the system is working properly.
switch off ends the process.
Outside The Box
Self diagnostics are always avai lable to the Star
Diagnosis unit, or its aftermarket equiva lent. With One quick note as we close: Not all low A/C
Star Diagnosis, not only wi ll you be able to pu ll outputs are caused by the refrigerant system.
and clear codes, but you wi ll also be able to acti- Mercedes-Benz uses electric heater contro l
vate output controls such as the A/C compressor valves to supply hot coo lant to its heater cores.
clutch, mode door contro l, and monitor signa l These va lves de-energized are open. Thi s way if
voltages in the data stream. This information can there is a failure in the system, you wi ll sti ll have
save hours of diagnostic time on dual and multi- full heat. If these valves do not clo se when
ple zone systems like Thermotronic. An exce ll ent commanded, they sti ll allow hot coolant into the
way to take advantage of the data-stream is to core. This can increase the temperature in the
monitor temperature sensor inputs and open ing cab in to a noticeable degree. Always make sure
percentages of mode door outputs. Mode doors the heater contro l va lves are closing properly
move from 0% to 100%. This shou ld indi cate to when the A/C isn't as co ld as your customers
you if a motor is binding or stuck. Th e would li ke it to be.
20 StarTuned

21. A MerGedes-Beuz should be Ime 10 lis origins. So lueu 10 Ihe MefGedes-Benz Classic:
CcmtP.l" for GP.nllinc: MC:ITc:cn~ IlP.n:;: Classic Parts. ThP.ir mrpnr~ have: nCCI'$!l to owr
40,000 tntP. fitting Gc:nllinr. Clnssic. Pnrts of the: highest qnality. pIlls a 12 month
lituiled warranly. They sell dlreGI, ship direGI aud even asslsl In paris speclClGaUon.
Mercedes-Benz Classic Center When you waul aulhenUG pariS, ouly Ihe SOUfGe wIll do. MBUSA,com/ClassleCenter
To speak with our Parts Experts, call our Parts Order Desk at 1-866-MB-ClASSIC (1-866-622-5277).
Mercedes-Benz Classic Center USA, 9 Whatney, Irvine, CA 92618
(..1/1
' or vi:.ir tor r:r1tiiTion<11dNnil:; <"Ind r, (;(IPY ot rhl~ I imiTcd fJ~m ;,,> Wnrrrliity. (<:l')(lOB Mcr(;r:dr.:;: Ih~'n7 USA, II C

22. Cushioning the Blow
As always, at Mercedes-Benz the top priority is the safety of
the people who drive its vehicles. Airbag systems need to be
maintained and serviced to ensure the same level of safety
that the engineers intended.
22 StarTuned

23. Mercedes-Benz has always been at the deployment, particularly as relating to children
forefront of occupancy safety. In 1969, United and smaller passengers.
States Federa l law mandated automatic Supplemental Restraint Systems (SRS)
occupant restraint systems . Yet, since 1967 have come a long way since the early
Merced es-Benz had been developing airbag generations. Complex computer algorithms
technology for its passenger vehicles . By 1980, differentiate between smaller and larger impacts,
the company had started to employ this seat occupancy detection sensors prevent airbag
advanced technology on a growing number of its deployment if a light-weight individual (child) is
vehicles. Initially, there were some of the same sitting in that seat, and dual/multiple-stage
concerns that we hear about today, such as how airbags have been only a few of the advance-
to prevent secondary injury as a result of airbag ments made over the years.
D
j '"
i
... ~
I)
-g ~
OI!'ll'OOlI!)ldaD
'1'11':.ia~ IU>Q-<'lOOl'O'I
This is a passenger seat occupant sensor and BabySmart™ transceiver for an older SRS
(later Occupant Classification Systems have their sensors sealed into the seat cushion).
These monitor if someone is sitting in the seat and the relative size of the individual.
Regardless, Mercedes-Benz highly recommends that all children be seated in the rear
passenger seats where they are safest.
StarTuned 23

24. COLLISION REPAI R I AIR BAGS
determined that there is a fau lt in the system.
What is the Goal? There are many DTC (Diagnostic Trouble Codes)
associated with SRS . It is your j ob to determine
While it is often believed that airbags are what code is setting and what testi ng procedures
deployed to counter forward impact in the event need to be implemented. Your Star Diagnosis, or
of an accident, this is not entirely true. If a body Compact III , can pull these codes for you and
flying forward is struck by a deploying airbag even he lp you step-by-step alo ng a diagnostic
traveling in the opposite direction, the impact trouble tree with the use of WIS.
might be twice as great, possib ly causing greater
When pulling codes from the SRS, you wil l
body trauma. The goal of an airbag system is to notice that there are "B" codes. As you may
dep loy fully before body contact and gradually know, the Society of Automotive Engineers (SAE)
slow down the body t hat is traveling forward.
imp lemented a program to homologa te automo-
This gradua l slowing process keeps points of tive service information among the various manu-
impact at a level the huma n body can absorb. facturers that sell vehic les in the Un ited States.
This also means the bag must fully inflate qu ick- You shou ld also know that when search ing fo r
ly, to the tune of about 40 milliseconds or less. A
diagnostic information either in the vehicle itself,
body not seat-belted in could impact the bag at or in service information, that DTCs have been
the wrong time and/or slide around the bag broken down into several categories, such as:
negating its intended purpose. Seat belts need to
be used to control the occupant's position and
• PXXXX Powertrain
maxim ize the air bag's effectiveness. In fact,
• BXXXX Body
some older systems were engineered to on ly
• CXXXX Chassis
respond with the respective seat belt fastened .
• UXXXX Communication
With different body types, both the distance
to the airbag (seating position) and energy of • Etc . h
impact differ. These facto rs also play into the
Since the SRS is part of the body, you will
SRS's effectiveness. So, mUlti-stage airbag
find that its DTCs are "B" codes. If you would li ke
systems were developed that can differentiate
to retrieve codes from the SRS, you need to
between more and less severe impacts and
select "Body." The next pull-down menu should
dep loy with on ly enough force to counter the
display SRS or Airbag. Upon retrievi ng codes you
forces exerted on an occupant during the
will notice all of these codes are "B" codes
accident. With this added sophistication comes
un less you have a communication fau lt. All "U"
added diagnostic comp lexity. Self-diagnostic
codes are for a fai lure in communication with
capability has been incorporated into each
one of the other contro l un its. There are two dif-
control unit and is mon itored during each ignition
ferent codes available from the SRS, first is t he
key cyc le to ensure that the SRS is functioning
"Stored Code" and second is the "Active Code."
properly. When t he SRS warning light comes on,
The stored code is a problem t hat was detected
the driver is directed to the "Workshop" to
using the SRS control un it's fai lure criteria, but is
address the problem. Th is not only serves as a
not currently a failure. These problems still need
warning to get the vehicle repaired, but also as a
to be addressed, but conventional diagnostics
warning that the SRS may not function properly
will probab ly yie ld no failed components at this
in the event of an accident.
time. Intermittent electrica l connections and/ or
system voltage issues cou ld flag this type of
"Visit the Workshop" code. Diagnostic testing should include more
in-depth procedures such as voltage drop to
If this warning message appears in the dri- arrive at any useful conc lu sion. The active codes
ver's information display, or after a four- to 20- are just that, active . Th ey are hard faults and are
second bulb check the Airbag or SRS warning occurring at that moment. Here, straightforward
light stays on, the SRS se lf-diagnostics have diagnostics shou ld find the cause of the DTC.
24 StarTuned

25. you wi ll now see a pull-down menu of the various
sections. Select Volume 5.1 and on the right side
of the page you wil l see another list of chassis to
choose from. Once you se lect a chassis within a
model production year (under se lection 16),
there will be displayed an additiona l list of
diagnostic service information to choose from.
The li st is broken down into three sections,
Diagnosis, Electrical Test Program (ETP), and
Control Unit Coding. Diagnosis gives you
troub le code tables, data PID actual va lues and
a symptom-based trouble tree among some
other cho ices. ETP gives you component
location and step-by-step trouble tree testing
for each circuit in the SRS . Keep in mind, these
testing methods are based on being a properly
equipped shop with the special service tools,
such as factory scan tools and breakout boxes,
that al low you to precisely follow the
test procedures.
Accident Damage
Yellow connectors and harness tape
If the vehicle has been in an accident,
indicate that this is airbag system
se lf-diagnostics indicate sensor data that can be
wiring. This is a two-wire squib for the recal led to help indicate what components need
door-mounted airbag. If you had a fault to be replaced and what sensors have failed.
code for this airbag, you would open Obvious repairs include SRS components that
this connector and measure resistance have deployed, or have received physical
between it and the SRS control unit. damage. You do not have to rep lace the contro l
unit, or other parts that were not damaged or
Once you have retrieved a DTC, you wi ll deployed, unless otherwise instructed by the
need to look up the proper testing procedures party responsible for repairing the vehiGle, such
for this / these code(s) . Here is where a paid as an insurance company. Obviously, if an airbag
subscription to www.startekinfo.com can pro- has gone off, it's going to need to be replaced.
vide manufacturer-specific, accurate and perti- Since the ve hicle is obviously being driven at the
nent testing for this particular problem . When t ime of the accident, the driver's side airbag is
dealing with vehic le s around the 2000 model going to deploy. Since the airbag is getting
year, you can look up service information in the replaced, we also recommend replacing the
" Launc h Manua ls" selection under Service Info, clock spring. What's a clock spring?
or in WIS-Net. There, you will be asked to se lect Since the steering wheel must turn to direct
the chassis of the vehicle you are working on. the veh icle and the driver's sid e airbag is in the
Once you have selected the chassis, look at the steering whee l, a device is needed that al lows
left side of the screen and you will see a list of the firing charge to make it to the airbag no
the various sections of the service repair manu- matter what position the steering wheel is in.
als. At the top of that li st should be "Body and The clock spring performs this task . It has an
Acc esso ries" just above "Chassis and electrica l connect ion on the steering column
Drivetra in." Select "Body and Accessories" and side . This is what carries the signa l from the SRS
StarTuned 25

26. COLLISION REPAIR / AIR BAGS
th at first. If the code does not come back right
away, simply turn the steering whee l and see if
the code returns. If it does, yo u can now be
more certa in that the clock spring has failed,
narrowing your search for the solution to the
code . Mercedes-Benz recommends that you
remove the airbag from the steering wheel and
insert a fixed resistance between the two termi-
nals in place of the airbag. Then, measure resist-
ance from either the steering co lumn through the
clock spring, or from the SRS contro l unit. At this
point yo u can turn the steering wheel and see if
the resistance changes. If it does, then you need
to replace the clock spring.
Used or reconditioned airbags?
In the unfortunate event of a collision,
Mercedes-Benz does not recommend the
the SRS works so fast the bags are fully in sta llation of salvaged, used or reconditioned
deployed by the time an occupant airbag system components since they can
makes contact with them. strongly compromise the safety features of the
ve hicle, leading to an increased injury or even
contro l unit. This side of the clock spring is
death risk to the occupants .
mounted solidly to the steering column. A flexible
Used or reconditioned airbag components
band of wire is mounted in the clock spring and
do not ensure the same safety features as new
carries the current through to the other side.
components, due to the following;
This side is solid ly mounted to the steering
wheel. It is the flexible band of wiring that main- 1. History of the component is unknown
tains the electrical connection while the wheel is (pre-existing damage, remova l or
being turned, not the brushes you might expect reconditioning processes, etc.)
from having seen cruise or radio controls 2. Airbag components are specifical ly developed
mounted in the steering wheel. Since the for each ve hicle, working together with other
steering whee l is used every time the ve hicle is safety systems (e.g. safety-belt, sensors, etc.),
driven, th is flexible band gets expanded and resulting in the fact that not every airbag is
retracted constantly. Although engineers take compatible with every vehicle.
every precaution to build a component that will
last, it will eventual ly wear out. Given sufficient 3. During the life-cycle of a model, several
use, it wil l final ly break and the connection will enhancements may have been introduced (new
regulations, new deve lopments, new parts,
be lost. This can also happen if mechanical work
outside of the ve hicle is performed. The act of etc. ). Salvaged, used or reconditioned airbag
changi ng a power steering gear can damage the compo nents do not ensure the fulfillm ent of
clock spring if precautions are not taken. If the the latest requirements.
steering knuck le is not carefully removed (and For all of the above reasons, Daimler AG
we know how hard that can be sometimes) strongly recommends that no sa lvaged, used or
excessive steering shaft movement can be reconditioned airbag component be installed on
transmitted up the steering column and damage any Merced es-8en;z in the interest and safety of
the clock spri ng. all parties (drivers and vehicle's occupants, insur-
Another simple diagnostic test is to clear ance companies, repairing workshops liability).
the clock spring code. If the code returns right Next time, we'll/ook at the Emergency
away you have an open in the "Squib" circuit. Tensioning Device (ETD), further testing
This is more than likely the clock spring, so test and checklists.
26 StarTuned

28. Small Repair, Big Opportunity
One of the benefits of owning a Mercedes-Benz Mercedes-Benz has the answer. The Small Repair
is the timeless style it exhibits. With bodies and Program was instituted earlier this year to allow
interiors sculpted like artwork, it's no wonder their Mercedes-Benz dealers and Mercedes-Benz Certified
owners take pride in them. Unfortunately, Collision Repair shops to handle minor repair jobs at
in the real world things happen . Stones are thrown their facilities without a large investment in time or
up from the roadway, careless passengers spill money. This comprehensive system provides the
things, wheels contact curbs, and road grime and tools necessary to repair surface damage to alloy
salt attack those nice rims. How are we going to help rims, windshields and interiors by means of easy-to-
our appearance-conscious customers? use and conveniently-packaged kits.
Sticks and Stones
The windshield repair kit has all the components needed to fix cracks
and stone chips. Resins are used to seal the glass, and polish takes care
of any pitting. All the necessary tools, such as syringes and drill bits, are
included to complete the job. Keep in mind that this kit is only intended
to repair minor problems outside of the driver's field of vision, and are
not meant to take care of a problem that has failed a state safety
inspection program.
Wheels
No part of the vehicle is more noticeable than those alloy rims.
Unfortunately, even the most stunning wheels are bound to be damaged.
The rim repair kit comprises cleaners, fillers, activators and the tools to
apply them. An array of colors allows you to color-match the surface of
the rim and provide a finish just like a new rim at only a fractio n of
the cost.
Inside Job
The interior repair kit is extensive. It's designed to hand le blemishes in
the vehicle's interior paneling and upholstery. It can even go so far as to
repair exterior plastic components such as the bumper. Fillers, reinforce-
ment material and applicators are only some of the materials supplied.
Included in the kit are color-matching compounds that will blend in with
the original colors and textures of the interior. Hard and soft plastics can
be repaired along with leather and vinyl.
Teamwork
Mercedes-Benz has teamed up with Reliable Automotive Equipment to
provide these kits to you. They amount to a cost-effective solution for
small repair jobs that will restore the finish that every Mercedes-Benz
deserves. To further support this small repair program, Reliable
Automotive Equipment includes a training DVD with each kit, and
peer-to-peer training is also available. To order these kits, contact your
local authorized Mercedes-Benz dealer.
28 StarTuned

29. · Should the gpllg·get .g littl~{o-qgb _· - ..~~ .
- - - • - .. • - - - I -- : ' _ ~" , ~. ' ~~'. - - .:. '"' - -.__ ~ ~,:- ~ - -- __ - _.. :.
_ __ ~ - I -.. ' ..... _ - . , ......
Small scratches, stone impacts, dents and blemishes -
and th e custom er's Mercedes can quickly lose the shine
from its exterior. And because that is annoyance enough,
we keep the costs for a repa ir as low as poss ible - with
Mercedes-Benz Small Repair. Special repair methods mean
that small appearance defects vanish in next to no time.
It goes without saying th at our kits meet the high, tested
Mercedes-Ben z quality standards th at you expect. So if you r
customers are driving aro und with a small imperfection, it
may be able to be repaired with Mercedes-Benz Small
Repair. Small Repair Kits are availab le from yo ur authorized
Mercedes-Benz dealer.
Training on th e Small Repair methods are availabl e from
Reliable Automotive Eq uipment. Please contact Reliable
Automotive Equipment to inquire about training yo ur
staff to perform these repa irs quickly and efficientl y.
RAE RELIABLE AUTOMOTIVE EQUIPMENT, INC.
1.800.328.7855

30. STARTUNED
FACTORY SERVICE BULLETINS
Whi ning/High-Pitched Whistle
Comi ng From Front of Engine
All Light Truck Models Equipped
wit h Engine M272 or M273
A whi ning or high-pitched whistling
noise com ing from the fro nt secti on of t he
engine may be caused by a faulty upper
idler pu lley. To resolve, rep lace the up per
idler pull ey with a new un it. The pul ley is
supplied as a package co ntain ing th e Parts Information
mounting bolt, dust cover and space r. Fit Quantity Part Name Part Number
the spacer between the timing case cover Ti ghtener Pull ey A272 20208 19
and guide pulley.
1. Remove doo r li nin g. Refer to WIS document
Knocking N oise in Rear Door
AR72 .12-P-101OGZ (164) or
When Operating Power Window AR72. 12-P-101 0RT (251).
Model I 64. I 22/ I 72/175/ 177 2. Remove doo r mod ul e. Refer to WIS document
AR 72. 12-P-010 3GZ (1 64) or
186/822/87 1 /886, AR 72. 12-P-0103 RT (251).
up to VIN A258996, 3. Remove broken limit stop from door.
Model 25 1.1 22/156/ I 65/175/177, 4. In sta ll new li mit stop (Figure 1).
up t o VIN A058266 5. Reinstall doo r mod ule. Refer to WIS document
AR72. 12-P-010 3GZ (164) or
AR72. 12-P-0103RT (251).
6. Rein sta ll doo r lining. Refer to WIS document
AR 72. 12-P-101OGZ (1 64) or
AR72. 12-P-101 0RT (251).
7. Renorm alize power wind ows .
A knock ing noise that occ urs when th e powe r
Parts Information
window is operated downwa rd and reac hes the lower
Quantity Pa rt Name Part Number
limit position may be caused by a broken plasti c li mit
Li mit Stop A164 73000 28
sto p. To remedy, perform the fo ll owing.
30 StarTuned

31. STARTUNED
GENUINE MERCEDES-BENZ PARTS ... NEARBY
Belmont Palo Alto Walnut Creek
Alabama Autobahn Motors Park Avenue Motors Mercedes-Benz of Walnut Creek
650-637-2333 650-494-0311 925-937-1655
Dothan
Mike Schmitz Automotive Beverly Hills Pasadena West Covina
334-794-6716 Mercedes-Benz of Beverly Hills Rusnak/ Arcadia Mercedes-Benz of West Covina
310-659-2980 626-795-8004 626-859-1200
Hoover
Buena Park Pleasanton
Crown Automobile Colorado
House of Imports Mercedes-Benz of Pleasanton
205-985-4200
714-562-1100 925-463-2525
Colorado Springs
Huntsville Calabasas Riverside Mercedes-Benz of Colorado Springs
Mercedes-Benz of Huntsville Mercedes-Benz of Calabasas Walter's Auto Sales & Service, Inc. 719-575-7950
256-837-5752 818-591 -2377 951-688-3332
Denver
Carlsbad Rocklin Murray Motor Imports
Mobile Von Housen's Motors
Hoehn Motors 303-759-3400
McConnell Automotive 916-630-8877
760-438-4454
251-476-4141
Chico Sacramento Littleton
Montgomery Courtesy Motors Auto Center Mercedes-Benz of Sacramento Mercedes-Benz of Littleton
Jack Ingram Motors 530-893-1300 916-924-8000 303-738-7700
334-277-5700 San Diego
EI Dorado Hills Westminster
Mercedes-Benz of Eldorado Hills Mercedes-Benz of San Diego Mercedes-Benz of Westminster
Tuscaloosa 916-567-5100 858-279-7202
Leigh Automotive 303-410-7800
205-556-1111 Encino San Francisco
Mercedes-Benz of Encino Mercedes-Benz of San Francisco Connecticut
Alaska 818-788-0234 415-673-2000
San Jose Danbury
Anchorage Escondido
Beshoff Motorcars Mercedes-Benz of Danbury
Mercedes-Benz of Anchorage Mercedes-Benz of Escondido
408-239-2300 203-778-6333
907-277-3383 760-745-5000
Fairbanks Fremont San Jose Fairfield
Auto Service Company Fletcher Jones Motor Cars Smythe European Mercedes-Benz of Fairfield
907-456-6217 510-623-1111 408-983-5200 203-368-6725
Arizona Fresno San Luis Obispo Greenwich
Mercedes-Benz of Fresno Kimball Motor Mercedes-Benz of Greenwich
Chandler 559-438-0300 805-543-5752 203-869-2850
Mercedes-Benz of Chandler San Rafael
Glendale Hartford
480-403-3400 R.A.B. Motors
Calstar Motors New Country Motor Cars
Phoenix 818-246-1800 415-454-0582
860-278-2000
Phoenix Motor Santa Barbara
602-264-4791 Laguna Niguel
Mercedes-Benz of Laguna Niguel Santa Barbara Auto Group New London
949-347-3700 805-682-2000 Carriage House of New London
Phoenix
860-447-3361
Schumacher European Santa Clarita
480-991-1155 La Jolla
Heinz Gietz Autohaus Mercedes-Benz of Valencia North Haven
Tucson 858-454-7137 661-753-5555 Mercedes-Benz of North Haven
Mercedes-Benz of Tucson 203-239-1313
Los Angeles Santa Monica
520-886-1311 W.I. Simonson
Downtown L.A. Motors Delaware
213-748-8951 310-526-4700
Arkansas Santa Rosa Milford
Manhattan Beach
Fayetteville Carwell Smothers European I.G. Burton
Mercedes-Benz of Northwest Arkansas 310-303-3500 707-542-4810 302-424-3042
479-521-7281 Modesto Signal Hill Wilmington
Modesto European Mercedes-Benz of Long Beach Mercedes-Benz of Wilmington
Little Rock 209-522-8100
Riverside Motors 562-988-8300 302-995-2211
501-666-9457 Monterey Stockton
Mercedes-Benz of Monterey Berberian European Motors Florida
California 831-375-2456 209-944-55 11
Clearwater
Anaheim Newport Beach Thousand Oaks Lokey Motor
Mercedes-Benz of Anaheim Fletcher Jones Motor Cars Silver Star A.G. 727-530-1661
714-777-1 900 949-718-3000 805-371-5400
Oakland Coral Gables
Arcadia Tonrance
Mercedes-Benz of Oakland Mercedes-Benz of Coral Gables
Rusnak/ Arcadia Mercedes-Benz of South Bay
510-832-6030 305-445-8593
626-447-1117 310-534-3333
Bakersfield Palm Springs Van Nuys Cutler Bay
Mercedes-Benz of Bakersfield Mercedes-Benz of Palm Springs Keyes European Mercedes-Benz of Cutler Bay
661-836-3737 760-328-6525 818-461-3900 305-251-0345
StarTuned 3 1