Hello Everyone,

I recently purchased a 2003 E500 with only 36K miles for my mom to drive and I am having some problems with the way it is running. Basically upon gentle acceleration between 35-40 MPH I feel a strange vibration like the engine is "shuttering" or running rough at that speed only. I do not notice it while decelerating or if I am accelerating quickly it is also not apparent. Also it only seems to happen after the car is fully warmed up. I can feel the vibration on my foot through the gas pedal and also any passengers can notice it as well.

Two weeks ago I took it to my trusted Mercedes independent mechanic and he said there were no codes showing. We decided to change the spark plugs and wires and that did help quite a bit but the rough running is still present. Also I have since had the tires rotated and balanced as well to rule that out.

Also when I feel the vibration I watch the RPM's and there is no fluttering etc. Someone mentioned maybe motor mounts but I can't imagine that would be it because the problem seems to happen only at the specific speed range.

One other issue I am having is during normal driving I will occasionally hear a "thump" sound coming from somewhere behind me. The trunk is empty and I made sure the spare tire and tool kit were completely secure. I cannot seem to figure out where that sound is coming from! It happens at the strangest times that are not necessarily associated with sudden braking or pot holes in the road etc.

Hopefully someone can chime in here who has lots of experience with this car

Thank you!!!
Jerome

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05 E55
03 E500

You're not going to like this... Have your mechanic test the transmission fluid for the presence of engine coolant (glycol). This car was built during a time period when Mercedes used Valeo radiators which have a tendency to leak coolant into the transmission fluid. The presence of glycol damages the torque converter and/or clutches in the transmission. The "correct" remedy is a rebuilt trans and replacement torque converter. I have read that if the problem is not too pronounced a fluid change and of course a new radiator may be sufficient. Try cranking up your Google-fu; there is plenty of discussion on this topic both here and on other MB forums.

Hi jcyuhn,

Thank you very much for that lead and sorry for the late reply. I have since looked up lots of info on this topic of glycol in the transmission. I also got the chance to talk to an acquaintance who is a very seasoned mercedes tech and he mentioned if it wasn't the problem that you said then it is probably the conductor plate. I am going to do some more digging on that note but thank you again for your response!

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05 E55
03 E500

conductor plate is a common problem... fortunately not a real expensive one.

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1989 300ce 129k
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1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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Makes sense to me because if it really were an engine misfire (bad enough to feel) you certainly would have a check engine light.

I've handled lots of mystery clunks before, but hard to diagnose over the intercomputer thingie. Is there anything at all you can say that would help, as far as the odd times? How about going up or down a hill or accel/decel???
If it seems like it's in the trunk, can you pop the decklid and forceibly shake it up and down? If you have fold-down rear seats you can fold them down and drive like that for awhile. Otherwise it also could be suspension or brake related. Tough things to diagnose sometimes.

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Hello Everyone,
I thought I would update this scenario since I am getting very close to pulling the trigger on a complete transmission rebuild..
Basically six months ago we did the test that concluded there was in fact glycol in the trans. At that point my trusted MB independent replaced the radiator to solve the immediate issue and we proceeded to flush the transmission fluid a total of three times. The shuttering problem was significantly less noticeable and I decided to wait and see what happened over time.
Now the problem has progressively gotten worse again and I am at a crossroads of either replacing the torque converter or the entire transmission. I understand the labor cost to replace either is about the same which makes me lean towards doing the whole thing so I know the problem will be fixed for good.
My question is does anyone know of a good transmission rebuild shop in Northern CA (Sacramento or surrounding)? I have heard about a place in Burlingame but I do not the name. Any other ideas about sourcing a reasonably priced new or rebuilt trans? I was thinking I could maybe save some cash by having a shop rebuild the actual trans in my car since I am only at 40K miles and perhaps that will have some cost savings. Am I way off base here?
On a side note the thump in the trunk has been diagnosed as the rear shocks being locked up.. I am going to wait on this until after the trans. I wish I could weld some brackets to fit some Monroe shocks off the shelf and call it a day!
Thanks for everyone's advice.

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05 E55
03 E500