I recently bought my first MB, a 1998 C280. using the VIN, I contacted the original owner who told me that the only problem he had with it was it "went through motor mounts" every 30,000 miles. Is this something peculiar with my car or a generic problem with the C280? Also, is there a "fix" to prevent this from happening? He said (and the dealership confirmed this) before the machine had 70K on it that he had to replace them twice at a cost of over $700! OUCH!

The part number on those motor mounts have changed 4-5 times, with each number change the mounts were modified. They should last 75K miles at least!
Does the engine vibrate??

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I actually bought this car from Carmax (I know! yuck!) after I investigated and talked to the original owner and the dealer who did the service. The motor mounts were changed just before I bought it. The original owner said they would probably last another 30K. Right now, it has absolutely no vibration whatsoever, but I am a little worried with its history of 2 replacements already! (once at 30K and again at approximately 70K)

I would not consider that to be normal. Twice in 70k miles seems odd.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

No doubt! And thus my concern! The car seems to be in great shape and is running beautifully right now. I just want to address this possible issue heads-on so I can stop it before it gets any worse.

my motor mounts and transmission mounts were replaced at about 30k under warranty although I had not specifically requested that be done. However, after they were replaced, at a stoplight the car was amazingly smooth, no vibration. So despite what they say about a inline 6 being inherently smooth, the motor mounts have a huge impact on cabin smoothness since no tuneup was done.

Recently, the car now has 63k and the car, of course, is not as smooth as when the motor mounts were changed but I recently notice that when starting the car, the last moment before the car settles into an idle there seems to feel a momentary rotational shift in the engine or out of sync feeling. After that, it is normal. Anybody know what might be the cause of that?

The previous owner of my MB said that the way you would first notice it was when the motor was idling, it would be noisy/rough.

Height measurement of the mounts is used to gauge wear, and replacement is called for when they settle past a certain height. You can replace them before that, if the engine vibration is objectionable, but I don't think there's a mechanically functional reason to do so, as long as a bolt isn't broken or something.

I have been awaiting a 3rd party shop manual (on CDs) to review this problem. Still waiting on its arrival. Are there only two motor mounts? If so, are they relatively easy to access to measure (for wear)? If they are, I will try and keep a check on it. Thanks for the info!