E240 unusual vibration

Beemer,

I don't believe that the harmonic crankshaft balancer (aka "the hand grenade option") would cause this sort of vibration. Usually there is a slight knocking sound before they shatter. Now of you haven't had yours replaced in 60K miles then it's time to have it done anyway.

How many miles are on the car? If it's in tune, then perhaps your engine mounts are worn (they're fluid-filled and when they leak you might see some oil-like residue on a cross-beam just behind the engine). I can't speak for a 240 vibration at 80mph, but the 320's I have don't do this. I seem to recall that tires out of balance usually cause a vibration at more like

50-60mph, but then again most tire shops don't do that good a job at balancing tires for higher speeds and if you have old/cheap rubber then this could be the culprit. Other than that, your front-end might need some care and attention - perhaps the steering dampener is shot or a wheel bearing is gone.

Josh

The idle vibration could be from a marginal spark plug, a marginal ignition wire, dirty fuel injector, etc etc. Adding a can of fuel injector cleaner to the fuel is a painless start and eliminates the fuel injector possibility. After that it's $$.

Tires have a static and a dynamic balance, at 80 mph the dynamic balance is the issue. Have a different tire shop check the tires for dynamic (high speed) balance.

Josh,

Thanks for the advice. I'm beginning to think it is the tyres even although they were synamically balanced. They will be due for replacement soon so this will help identify the problem.

Beemer

I don't believe that the harmonic crankshaft balancer (aka "the hand grenade option") would cause this sort of vibration. Usually there is a slight knocking sound before they shatter. Now of you haven't had yours replaced in 60K miles then it's time to have it done anyway.

How many miles are on the car? If it's in tune, then perhaps your engine mounts are worn (they're fluid-filled and when they leak you might see some oil-like residue on a cross-beam just behind the engine). I can't speak for a 240 vibration at 80mph, but the 320's I have don't do this. I seem to recall that tires out of balance usually cause a vibration at more like

50-60mph, but then again most tire shops don't do that good a job at balancing tires for higher speeds and if you have old/cheap rubber then this could be the culprit. Other than that, your front-end might need some care and attention - perhaps the steering dampener is shot or a wheel bearing is gone.

Josh

Yes but the idle vibration is only when moved from Neutral the Drive

Tires have a static and a dynamic balance, at 80 mph the dynamic balance is the issue. Have a different tire shop check the tires for dynamic (high speed) balance.