Vibration When Cold, revisited, 2000 W210

[gasman59]

Hi All:

A short time ago I asked for advice regarding a vibration/audible rumble-drumming that occurs when my car is cold. It occurs around 40 MPH.

After driving approximately 10 miles it goes away.
This seems to indicate something warms up.

The car is a 2000 W210 4-Matic Sedan. V6 Petrol, auto transmission, 70,000 miles.

Here are some tests I ran while cold:
Change gears via paddle shifter up/down: No change
Vary engine speed: No change
Brakes lightly applied: No change

Also:
Tires rotated/balanced: No change
Vary tire pressures up/down: No change

I am assuming this is suspension related. The only items I can think of that may "Warm Up" are the dampers (shock absorbers) or engine mounts.

I raised the car to inspect the drive-train.
The flex discs all look solid.

Are there any other suggestions as to where to look?

I know this is minor, but it is annoying while it occurs.

Thank you for your time.

 

[Parrot of Doom]

Don't exclude the tyres from this, one may be faulty.

 

[Sean Ng]

Dear gasman59

How about the catalytic converter? I once had a similar problem.

Regards
Sean

 

[gasman59]

Thanks for the replies.
I thought trying different tire pressures would rule out the tires.
I will have a tire shop inspect them.

Never thought about the cats. Did you replace them?

Thank You,
Ron

 

[Parrot of Doom]

One or more of the tyres may be faulty full stop. Pressure won't fix that.

Try changing each wheel for the spare, see if it goes away. Make sure you use the correct wheel bolts for the spare, you must use short bolts.

 

[nia-ja]

I have a 98 W210 240 that does the same thing. Thought the cause was the big thread winter tyres we use over in Norway, but it is still there after I changed to summer tyres. It goes away after ten minutes or so...
Is it a hard job to change out the engine mounts?

 

[television]

I do not tink that engine mounts are the problem as they would give it all of the time.

Has the fuid been changed in the box

 

[Aussie Nick]

I would suspect the gearbox.