1985 300SD vibration - PeachParts Mercedes-Benz Forum

okrhino · #1 10-20-2011, 07:39 PM

My car will vibrate while at highway speed,it is pretty bad I can feel it through the steering wheel but it also can be felt all throughout the car. This occurs at various speeds. All front end suspension seems tight,new tires up front,and tire balance ok. Also car vibrates while at idle such as while sitting at a stoplight but the vibration is less severe. This vibration is making me not want to drive the car. Does anyone have any other ideas what it could be or what I can check? Any help would be greatly appreciated.

The Gears · #2 10-21-2011, 03:53 AM

Is the vibration at wheel speed or drive shaft speed. Drive shaft speed will be same as engine speed in top gear. Feel the rubber engine mounts for splits or softening. Check along the exhaust system for possible body contact. How long since the tappets have been set. Tight tappets, not letting the valve close completely will cause a weird vibration. Coast down a hill in neutral, foot of the throttle. The engine is turning slow but the drive shaft is going fast. What do you feel then.
Let us know what you find.

SD Blue · #3 10-21-2011, 10:51 AM

The vibration at highway speed and the vibration at idle sounds like two different problems.
Idle vibration is usually due to a rack dampener getting weak. It's located on the rear of the IP. Check for a "gold" one. I'm speaking of the color, of course.

Highway speed vibration could be something with the drivetrain or tires.
First tire balance is usually the first I suspect because many tire shops don't take the time to get it done right. Alignment is another source. Even with a tight front suspension, worn trailing arm bushings, on the rear, gave intermittent problems of vibration but tire wear was the main indication.
For the drivetrain, flex discs, carrier bearing and u-joint. Usually noticed in the console area. You will need to remove the splash guard to inspect the carrier bearing and u-joint. From what I've experienced, the u-joint usually shows no evidence of problems until you remove the driveshaft for repairs.
Highway vibration needs to be sorted out by determining if it seems to be front end, drive train or after certain circumstances such as going into a curve or uneven pavement.