M103 Fixing List / FAQ / Links / Tips

[ps2cho]

So finally decided to start one. Will update later with more. I'm not the best mechanic and only know what I have done...so if anything is wrong, or needs correcting, call me out on it. I'm young and dumb Rules: Keep chatter to bare MINIMUM. NO Keep Thread Clean and to the point. NO Only post what ABSOLUTELY UNDOUBTFULLY fixed your problem First a foremost, here is the FSM for all to use...cough...I mean myself only for when I'm on the road and don't have the CD's. http://www.ps2cho.net/downloads/MB%20CD/W124/Main.html --------------- So onto the thread. I'll try and edit in everybody's responses until this post locks itself (I believe it does after X # of days then I can't edit anymore. But we should be able to lock in tons of info before then if everybody contributes what they know). I'm adding as many as I have personally done. Happy fixing! ---------------- Engine General Engine Problems Start Here Problem: So you got general engine problems? Start here. Fix: 1) Start by pulling Spark plugs and check the condition of them. Make sure they are gapped correctly. Here is a good link to spark plug coloring: DO NOT use Resistor spark plugs. The only spark plugs you should be using in this engine are NGK Non-Resistor, Bosch H9DCO (OEM), or Nology plugs. Most people complaining about power or problems altogether are simply using the wrong plugs. Resistance is built into the wires themselves. This is why resistors run like crap! I have read, but nobody has confirmed doubtfully that resistor can actually cause damage to some of your ignition components. Just get non-resistor and be done with it! 2) Check resistance on ignition wires using a DMM. It should be obvious if you have a bad wire as each one should be reasonably close in resistance. If in any doubt due to appearance, replace them. Correct resistance should be printed on the wire. My Beru's were 1k ohms. 3) Pull of Distributor Rotor and Cap. DIY Link Here mid-way down Clean each of them at the very least, but if in doubt at all, replace them. Together brand new they won't cost you more than $60. 4) Check your A/F mixture. Look below. --This should now have you confident that the basics of your ignition system are OK. From here you can move on further, but you should start here before doing less common and more difficult things. Duty Cycle/ Air-Fuel Mixture Problem: You want to check your A/F Mixture ratio. Fix: Here is a GREAT article on it. Here is the link on it. What you need to understand from this, is that the system compensates when in closed-loop mode. Obtain a 50% reading when the engine is WARM AND in closed-loop and LEAVE IT ALONE. Bottom-end Power problems. Problem: Bottom end power problems. Fix: I had this problem on my 260E. It would bog down and refuse to accelerate at all at the bottom end. Towards the top end it would clear up and scream, but the bottom end was lifeless. Replaced EHA and it fixed it. Front Timing Cover Oil Leak Problem: Oil is leaking somewhere at front of engine Fix: First make sure this is where it is leaking. The front timing cover is the most common leak place. First remove the distributor cap and clean the top of the lower timing cover completely. Now drive the car for a day and check if there is any oil on your clean lower timing cover. If there is, it is the upper timing cover leak. Here is a good DIY article on it. Follow exactly what it says and you should have no more leaks unless the seal you put on falls out of place upon refitting. Make sure to use gasket maker where he shows because it works perfect. I have done it twice. Head Gasket Problem: Head Gasket is leaking Fix: Alrighty....common thing on the M103 at SOME point in its life. Can be as early as 70k, or anywhere up to 180k. I won't go through the procedure, because this thread is absolutely GOLDEN. Here is the link for it. My tips: Do as he says and DETACH the intake manifold from the head, do not remove it with the head. Reason? You save yourself a lot of time and headache. Why remove something with all the fuel lines, electronics and what-not when you don't have to? The FSM states to remove it, but I had no problem leaving it in the car. The intake manifold bolts are a tad tricky to remove, but its not impossible. You will thank yourself upon refitting. Get the head reskimmed and have the valve guides + seals done. I paid $300 for it, but once that is done, you KNOW that head is good for another 100k miles or more. Peace of mind. The valve guides DO LEAK on the M103. It is very common and valve stem seals are a BAND-AID fix on the problem if you are burning oil. Here is my thread on my rebuild. I have lots of high res pics. Engine is burning oil Problem: Losing oil...but no leaks? Fix: Valve stem seals and/or guides are leaking. Another common problem. You can do the valve stem seals without removing the head, but you will need some tools. Here is my posts on it. Post #43 onwards OVP -- The OVP sits behind the battery with the rest of the computer relays. Symptoms: 1) ABS Light on 2) Frequent stalling when coming to a stop, or stopped completely. Fix: First check the fuse. Next remove and shake to see if anything rattles. If fuse intact, and problem persists, replace. People have tried resoldering, but it either a) failed b) lasted a very short time. I have had ABS Light on both my w124's FIXED due to this. My 88 300TE used to stall at lights, it fixed this. I can vouch for it. Coolant Leak around Water Pump/Leaks in general Problem: As above Fix: First check that the thermostat housing isn't leaking. If you still have the plastic one, purchase the updated metal housing. It should be obviously stained right below the housing if it is leaking. The updated metal housing fixed it. I first tried reseating it, but there were small hairline cracks in the plastic, so I got the updated metal one from the junkyard. If the coolant leak is NOT coming from the thermostat housing, check all hoses by the radiator in case they are leaking, then it is safe to assume the water pump is beginning to leak and may need replacing in the near future. Here is a DIY link on its replacement. Suspension Problem: Your W124 feels like a huge wobbly boat on the highway, You feel like your being blown off the road by gusts of wind, car tracks to the left or right only under acceleration. Cause: Your rear suspension links have badly worn bushings, your rear subframe bushings are shot. What end of the screwdriver do I hold?: There are 5 rear suspension links per side, they are the links that extend from the rear control arm to the frame, observe the bushings on each end to determine is replacement is needed. They should NOT wobble or look worn. There are two rear subframe bushings located on each side of the rear suspension carriage, take a peek and determine if they need to be replaced also. Fix: (If your handy with a wrench) I did both the subframe bushings and rear links for both sides along with rear differential mount bushings in my garage, on the floor, using cyinder blocks (not recommended) You will need a bottle jack to jack the subframe bushings out of the sub frame and some blocks of wood to jam between the car frame and the subframe when popping them out with the bottle jack. Here's a nice DIY http://www.peachparts.com/shopforum/...53&postcount=5 Air Conditioning Climate Control Relay -- This sits near the OVP and is labeled "Klimate Control". Symptoms: Fan clutch clicks, but never fully engages. A/C level is fine. Fix: Replaced Climate Control Relay and fan clutch successfully engaged. Vents blow warm air Problem: As above. Fix: I had this problem on my 300TE for a while. Resoldering the unit that sits behind the wooden A/C panel made it better, but it failed within a few days again. Replaced it with one from ebay and no more hot air. Transmission / Driveshaft Car slips back after parking / Freeway rumbling Problem: As above Fix: Flex disks are most likely shot...but the w124 will slip back to some extent regardless. Just get used to using the parking brake. If it still slips with parking brake engaged, the PB shoes are broken, or need an adjustment. --Rumbling on the freeway under acceleration would be the flex disks, could be back or front, although USUALLY its the front only. Interior/Body Windows Problem: Window will not go up/down. Fix: First thing to do is check fuse box and swap the window switch at center console with a working one from a different window. Second pull off the door panel (DIY link on panel removal here). The power cables to the motor will be black + green. Follow them to the motor and apply power using 12/18V battery or starter battery. Be very careful when doing this and make sure car battery is disconnected to protect fuses and OVP. . If the motor does not respond or click at all. Replace motor. Reading light stays on when car is locked Problem: The interior top light/reading light stays on even when car is locked and you walk away. Fix: Assuming you have it in the correct position (fully towards front of car)...I replaced the unit from one at the junkyard and it fixed it. Blinkers/Window Wipers act all odd Problem: Wipers are not consistent...Act all funny. Fix: Resolder Combination Relay. Here is my DIY Link on it Ignition Key won't turn Problem: As above Fix: At the first sign of problems, get the key into the 2nd notch and LEAVE IT. Get it fixed ASAP!!! Once you are no longer/not able to turn to the 2nd notch, you have to cut the tumbler out by force. If you can get it turned to the 2nd position, consider yourself very lucky and get it changed using the tool in the link below. If you cannot turn it, keep trying for a little longer. Once you have you completely exhausted all chance it will turn by luck, squirt some WD-40 into there and try again. At this point try anything/everything because you gotta drill it out anyway. Some people have had success with an electric sander in hopes the pins will fall back into place allowing you to turn it. Once that fails, either A) take it to a Benz Indy, or B) Get your dremel and allow a lot of time + hours Here is my thread on my cutting and tools I used Euro Headlights Install Problem: You don't know how to put them on!! Fix: Here is a great DIY link on it.. I highly recommend DEPO euros if you can't afford the OEM Bosch Euro's. They are about as close to OEM as you can get and can be had for around $180.

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[ps2cho]

Thanks

Hopefully we can just make it easier to find answers on our own....as let's face it, we all hate searching and for the most part, searching doesn't always bring the answer, or even ideas. At least if this thread goes in the right direction, people can have ideas, or solutions!

[gorillajin]

Excellent!!!
I read your HG DIY thread and it was very fun.
I know I have to do this someday, and actually you made me think that I can do this myself. I love working on cars although I am not that good.
I have changed the belt, tensioning shock absorber, and upper guide pulley so far. The hardest part for me was removing and installing the fan clutch due to stupid MB design.

Anyway, thank you so much for your post.
Thumbs up!!!!!

[appatula]

Suspension

Problem: Your W124 feels like a huge wobbly boat on the highway, You feel like your being blown off the road by gusts of wind, car tracks to the left or right only under acceleration.

Cause: Your rear suspension links have badly worn bushings, your rear subframe bushings are shot.

What end of the screwdriver do I hold?: There are 5 rear suspension links per side, they are the links that extend from the rear control arm to the frame, observe the bushings on each end to determine is replacement is needed. They should NOT wobble or look worn. There are two rear subframe bushings located on each side of the rear suspension carriage, take a peek and determine if they need to be replaced also.

Fix: (If your handy with a wrench) I did both the subframe bushings and rear links for both sides along with rear differential mount bushings in my garage, on the floor, using cyinder blocks (not recommended) You will need a bottle jack to jack the subframe bushings out of the sub frame and some blocks of wood to jam between the car frame and the subframe when popping them out with the bottle jack. Here's a nice DIY http://www.peachparts.com/shopforum/...53&postcount=5

[Wolfe190]

I'm a 201 guy but since I'm running a 3.0 right now I'll share what I've done. I've seen lots of threads asking "how do i get more power out of my m103?" Here's what I've done:

2.5" exhaust tubing, ditch the precats (just below the exhaust manifolds), magnoflo hi-flo catalytic converter, flowmaster 50 series muffler. I kid you not that this setup sounds like a small Mercedes V8. I finally got a camera and will be posting videos soon.

Steal some AC ducting out of just about any old MB. My choice was a 123 chassis since it was being parted anyway. You need about 4 feet of it (two complete sections will suffice). Cut a small oval hole in the rear of your airbox (about 3" across, 1.5" top to bottom) and plug it in! I figured this was a simple way to insure full usage of that huge air filter.

The R-16 resistor is real. Trash it. I read about it for monthes before I decided to give it a try. I went to unplug the thing and it had already completely corroded itself into nothingness hahaha. So there is definetly nothing to lose there.

If you can mate a LSD to the back of your M103 your car will be sooo happy!! Thankfully for me (being a 201) it was a pretty easy search. The next thing is a set of "LSD spring blocks". These are a custom item that I was able to track down thru a member on 190rev.net. They work perfect. He offers two sets of springs, I opted for the "performance springs", which are much stiffer, and bring your lock to about 80%. The install is straightforward, easy, and you can learn a few things along the way, as well as replace those leaking seals!!! The extra lock is great for drifting, and only slight popping in parking lots. But it will tear up your gravel driveway if you have to make any sharp turns to get out lol.
Thats all for now. I'll post pics and maybe a video when i get a chance. Happy motoring!

[epowers777]

Someone sticky this excellent!!

My key board is broke hopefully u can edit this up
How to test ur idle valve.

My car did this to me at work was embarrassing
car wont start cold? try this:

(while cold and wont start) Open flap with ur finger and spray starter fluid in it. Start car while pressing on gas peddle (might take a few sprays) when starts rev engine let go of gas pedal. (if it dies go to next step if not check ur 7 injector) Then spray starter fluid and repeat steps. When car starts rev engine until it warms up(dont let go of gas) It will take awhile. when warm let foot off gas if it idle that means ur idle valve is not working replace it.

Is my temp sensor working? (the on that controls computer)
while idling kick on ur ac ur elect fan should turn on. If it doesnt then replace ur temp sensor.

[roach_juts]

GOOD JOB !!!!!! very help full info !!!!!

[epowers777]

Just came across this
Need to decode your cars vin:

Decode Here

Decoded my car very interesting!

[roach_juts]

you for got to include neutral switch trouble shooting or fix ..... just a suggestion
thanks

[ps2cho]

Originally Posted by roach_juts

you for got to include neutral switch trouble shooting or fix ..... just a suggestion
thanks

I've never run into this...so if somebody has, post it up.

Looks like original post is already locked from editing....so just post up what you got.
Maybe a mod can edit it in or something every now and again? Or better yet...somehow keep the editing enabled?

[ps2cho]

I also HIGHLY recommend buying this book:
http://www.amazon.com/Mercedes-Benz-...2181031&sr=8-1

It comes with step-by-step guides on how to do all general maintenance procedures full of pictures. Transmission filter, power steering filter, rotor + pad replacement....everything. It actually beats the FSM because its simple and to the point. Everything is laid out nicely and has the pictures to support it.

It's also a great read on the car's history and development. I found it very interesting as it shows all the safety elements about the car then later goes in depth into the Bosch K-Jet system and a lot more. Its a solid purchase for $20.

[ps2cho]

Problem: Only when cold, engine somewhat hard to start and is rough for the first minute of driving.
Solution: Engine temperature sensor could be culprit. I just broke the plastic poles on mine while tightening it up and this instantly this started happening. Sometimes started within 2-3 seconds, but other times 10-15sec cranking pedal to floor before it started. Drives somewhat rough and sluggish until warm then problem disappears.

[Wolfe190]

I've got a great one this week!!

Problem for the last few monthes my ABS light has been coming on intermittently, becoming more and more often most recently. And in just the last month, it was accompanied by stalling, poor idle, loss of power. I've been doing research and have found quite a few other people who've had the same problem, but never found a conclusion

Solution OVP relay!!!! It takes about 4 minutes, requires a 13mm wrench to get the battery out, and a flatblade screwdriver to separate the old OVP from its plug.


When I picked up the new OVP my car actually stalled in the parking spot as I pulled up. Hasn't done any of that BS since. That 5 days ago At the peak of my troubles, it stalled 5 times going across town (which where I live is one straight shot, about one mile long with 4 stop lights lol)

[ps2cho]

Something that I learned as well from another forum. Do not jump-start W124's!! This is the number one cause for the failure of the OVP.
Remove the battery, charge it then put it back in instead of setting to boost mode and trying to start.

[pifcat2]

This should be a sticky thread!

[epowers777]

Fixing odometer


Ok here are some picsThis is if your shaft is turning
symptoms:
Numbers fall (right side) or numbers good and trip odometer doesnt work

Instructions below pics!!



Thats the gear we are concentrating on!!



Blue arrow is the shaft we will be removing.

Blue circle concentrate on how straight the numbers are if you rewind your odometer or fast forward make sure all numbers are straight. I look on craigs list and these guys go ,"look low miles" and the numbers are off. I can tell they rewinded there odometer.

The yellow arrow you need to put a screw driver in between the plastic frame and wheel to firmly press your shaft in. Mine was a pain I wack it hard witha screw driver end.



Notice the shaft on left and screw driver on right . Push on the screw driver will putting some resistance on shaft to keep together so the numbers wont fall. Pull shaft completely out while the screw driver wd40 hose toothe pick etc holds the numbers in. Also tilt left so shaft is facing dow while doing it the numbers stay in place easier.
Note yellow marks when installing shaft stick flat tip screw driver in spot to puch shaft in completely . If you dont the shaft will fall.



Pull shaft out completely and ruff shaft up with dikes. I did the whole shaft and it worked great. It will be hard to get back in be patient and dont be afraid to wak it good!!!
put shaft back in and put speedo in wont fall any more!!!


MORE COMING ON HOW TO REWIND OR FAST FORWARD ODOMETER WHAT EVER YOU DO DONT BE ILLEGAL AND REWIND ODOMETER TO BE A LOW MILES CAR.

[ps2cho]

^ Awesome. I will personally use that

-----------

This is for M104 head gasket replacement, but a lot of the same stuff applies for techniques
http://www.peachparts.com/shopforum/...d.php?t=147315

[latief]

This is my HeadGakset Replacement Thread also, it is for the m104 engine...not as clean of a thread as i would like, but hopefully it will help someone

http://www.benzworld.org/forums/w124...et-repair.html

[ps2cho]

Problem: Shock/Strut Mounts are cracked/broken
Fix:
**Be warned everything here is a potential danger**
If you remove the red nut, nothing will happen when the wheels are on the ground. The weight of the car holds the spring tight. If your strut is worn enough, you can hit it through the mount with a rubber mallet and pull it down far enough to have the strut completely free. With this out, remove the 4 bolts and off the mount comes! SUPER easy and there should realistically be no danger involved while the car is on the ground. (I have not done the following, but have read) -- If your strut is newer and you can't push it down, jack the car up (with nut screwed back in), remove wheel, and support lower control arm with quality hydraulic jack (NOT THE WEIGHT OF THE CAR. Your other jacks are doing this. This jack is purely to keep the spring compressed). This will allow more space and now undo the bolt. No spring compressor is needed. Be safe though.

[epowers777]

Look what I found!!!!


Mercedes Code Retrieval
Accessing Diagnostic Trouble Codes
With Impulse Counter
• With ignition switch On and shift lever in P/N position, connect impulse counter.
• Depress Start button for at least two seconds but no more than four seconds, read codes.
• Read codes until first code displayed appears again.
• Codes will appear in ascending order.
With On-Off Ratio Readout
• On models equipped with on board diagnostics, depress non-locking switch to convert control unit to read on-off readout ratio codes.
• On all models, install on-off readout ratio tester to diagnostic socket.
• Allow engine to idle and oil temperature to reach 140-176?F (60-80?C).
• Read and record on-off readout ratio codes.
With Scan Tool
A hand-held tester can be connected to the underhood data link connector (DLC) X11/4 located at module box, or a generic scan tool can be connected to the generic connector X11/22 located in the tower edge of the instrument panel. To access diagnostic trouble codes, follow the tool manufacturer's instructions.
Clearing Diagnostic Trouble Codes
With Impulse Counter
o Complete required repairs resulting from recorded codes.
o With impulse code displayed, wait two seconds then depress Start button for at least six seconds.
o Each code must be erased individually.
o If no number is displayed, then diagnostic trouble codes are erased from memory.
o If code higher than one appears, codes are still stored in memory.
With Scan Tool
To clear DTC's, follow the scan tool manufacturer's instructions.
Diagnostic Codes
Mercedes
90-93 190E & 300 series (2.3L)
1 No system malfunction.
2 Throttle valve switch.
3 Coolant temp sensor.
4 Airflow sensor position indicator.
5 Oxygen sensor.
6 Not used.
7 Td signal.
8 Altitude correction capsule.
9 Electro-hydraulic actuator (EHA).
10 Throttle valve switch and/or Idle speed contact.
11 Not used.
12 EGR temp sensor.
91 & later 300 series (2.8L and 3.2L)
1 No faults.
2 Oxygen sensor inoperative.
3 Lambda control inoperative.
4 Air injection inoperative.
5 EGR inoperative.
6 Idle speed control inoperative.
7 Ignition system failure.
8 Coolant temp sensor-open or short circuit.
9 Intake air temp sensor-open or short circuit.
10 Voltage at Air Mass sensor too high or low.
11 TN (RPM) signal defective.
12 Oxygen sensor heater open or short circuit.
13 Cam position sensor signal from-EZL/AKR ign. control unit defective.
14 Intake manifold pressure at start too low.
15 Full throttle Info defective.
16 Idle speed info defective.
17 CAN Data exchange-Malfunction between control units.
18 Adjustable camshaft timing solenoid-open or short circuit.
19 Fuel injectors-open or short circuit or Emission control system adaptation at limit.
20 Speed signal missing.
21 Purge switchover valve-open or shorted.
22 cam position sensor signal defective.
23 Intake manifold pressure w/ engine running too low.
24 Starter ring gear segments defective.
25 Knock sensors.
26 Upshift delay switch over valve-open or shorted.
27 Coolant temp sensor deviation between sensor ciruits 1 & 2.
28 Coolant temp Sensor.
91-93 190E and 300 series (2.6L and 3.0L)
1 No faults in system.
2 Throttle valve switch(full throttle contact).
3 Coolant temp sensor.
4 Airflow sensor potentiometer.
5 Oxygen sensor.
7 TNA (RPM) signal.
8 Altitude pressure signal from EZL Ignition control unit.
9 Current to Electro-hydraulic actuator.
10 Throttle valve switch(idle contact).
11 Air injection system.
12 Absolute pressure valves from ELZ ignition control unit.

[epowers777]

EGR LINK A Must read if you have an egr even if its running good.


Emission failure HCs and NOx

High HC) Hydrocarbon failures mean unburned gasoline is passing through the engine and entering the exhaust. The three most common causes include ignition misfire, lean misfire and low compression (typically a burned exhaust valve). Ignition misfire can be caused by worn or fouled spark plugs, bad plug wires or a weak coil. Lean misfire results where there is too much air and not enough fuel, so check for vacuum leaks, dirty injectors or a fuel delivery problem. In addition to these, hydrocarbon failures can also be caused by oil burning due to worn valve guides, valve guide seals and/or rings.

High CO) Carbon monoxide failures indicate an overly rich fuel mixture. On older carbureted engines without electronic feedback controls, look for things like a stuck choke, misadjusted or fuel saturated float or a rich idle mixture adjustment. On newer vehicles with electronic carburetors or fuel injection, the system may not be going into closed loop because of a bad coolant or oxygen sensor.

High HC and CO) If both HC and CO are high, the vehicle may have a bad catalytic converter or an air pump problem. See Troubleshooting P0420 Catalyst Code

High HC and NOx) NOx emissions: The Exhaust Gas Recirculation (EGR) system's purpose is to reduce NOx emissions that contribute to air pollution. If the EGR system is leaking or inoperative, it can cause problems including; Not Opening = detonation (knocking or pinging when accelerating or under load), Not Closing = a rough idle, stalling, hard starting, elevated NOx emissions and elevated hydrocarbon (HC) emissions in the exhaust.

What Im getting to is the bottom. If you have an egr valve and have symptoms pull egr clean (do not blow air will ruin it) The tube that goes to ur intake is clogged usually up by the intake side. Bore it out with a speedo cable or remove it. The intake side has a 90 degree turn so make sure u get it all.

[ps2cho]

More error code troubleshooting

[ps2cho]

oh wow stickied nice!

If I could just get the post unlocked so I can edit it...

[gorillajin]

If you hear loud ticking noise when start the car, try to change the engine oil to 15w40 diesel oil. I had this loud ticking noise(tapping) when cold start. the noise gets faster when you rev up the engine. It gets faded away when the engine gets hot.
After I changed the engine oil, it's completely gone. No more tapping noise when cold start or after.
Before you spend any $$$ on the engine, change the engine oil first.

Thanks.

[epowers777]

Use mobil delvac super 1300 15w40 (Cheap but good oil) Or a 20w50. Yeah I know theres a big controversy on oil pls save for another link. Use this cheap oil to make sure ur valves seat properly. We dont want u spending a ton of money on oil and ur valves still tap.
DO NOT USE ANY DIESEL OIL IN UR CAR DO RESEARCH FIRST MOBIL DELVAC SUPER 1300 15W40 IS COMPATIBLE WITH GAS ENGINES.