49mph-72mph vibration
 

For the last 2 weeks I am noticing a steering vibration which starts around 49mph and end around 72mph. The peak vibration takes place around 66mph.
Almost one month ago I had both engine mounts replaced (the transmission mount was also replaced).
The car is a 99E300TD with 78k miles on it.
I checked the steering fluid and is OK - I also looked under the car & seen nothing to be concerned.
Any advice on what it could come from?
Pat

Had the tire balance checked? This is the most common cause of steering vibrations

aLTERNATIVELY ROTATE TIRES AND SEE IF IT CHANGES ANYTHING

Could be lwr ctrl arm bushings. I have heard of them going out as low as 50k. Also, NEVER cross rotate your tires. I did this a couple of times and had probs with the belts wearing funny and causing vibration. For the minimal difference in wear, especially on a rwd car, why risk it?!

The tires have been rotated when mounts were replaced (about 4k miles ago). Also the tires were dynamically balanced a while ago.
Looking under the car I noticed that the passager side front wheel -inside - is missing the weight: it has only the weight clip visible with no weight. Could this be it?

Yup, you've got it!

Did the person who balanced it use "official" MB wheel weights? I've had regular wheel weights fly off with regularity, but MB weights seem to stay on better.

Yes, the weights are MB "official". Only the clip without weight is left on the inside of the wheel.

Ask yourself, "what's changed?". The engine mounts.

This problem surfaced shortly after that repair....right?

Faulty engine mounts or installation could cause what you're experiencing.

Mike, good question to ask. Yes, it surfaced after the mounts were replaced. All 3 mounts were MB original replacement parts.
The work I did it myself. I am wandering how could I mess-up - the replacement of engine mounts is very simple - the mounts self align into their location after which I tied-up the bolts. I replaced them at 71K miles. Now about 7K miles later I have this vibration issue.

Pat,
I'd say start with the basics. You know you have a wheel weight which has gone kaflooey -- rebalance that tire (you need to do so anyway) and see if that doesn't fix the problem. It MAY be totally unrelated to the motor mount R and R.

From my reading, and limited experience, vibration problems you can "drive through" (i.e., you can detect a discrete speed when it starts and stops) USUALLY turn out to be tire balance issues.

Make SURE that wheels are being Dynamically balanced with weights on the inboard AND outboard lip. There are many tire stores that insist on using weights ONLY on the inboard edge. This will allow the wheel to wobble.

Find someone who will do it right, this is the necessary first step.

Good luck,