RE: <E30> Searching for cause of low rumble......

["Fadeev, Alex" <Alex.Fadeev@xxxxxxx>]

> My bimmer's rapidly approaching 200K! Woohoo! It's an '87 325e.
> The engine is idling just fine at a stop light. Light goes 
> green and I rev the engine a bit and disengage the clutch. As
> I feed it more gas, if feel a constant vibration and hear a low
> rumble sound that seems to be emitting from the back half of 
> the car. I engage the clutch or take my foot off the gas and 
> the noise and the vibration goes away. It is most pronounced 
> between 1800 and 3000 RPM, seeming to level off as the 
> revolutions go above the 3k mark.
> 
> Now, I talked to a friend who knows cars pretty well about 
> the issue. He said that it is most likely the U-joints. Are 
> there any other suggestions please?? Also, could you tell me
> an approximate cost for your suggestions.

Guibo/flex disk. The ~ $60 rubber driveshaft vibration dampener right behind
the transmission. Unless you've replaced yours in the last 100K miles, it is
gone and that will result exactly in the symptoms you are describing. 
On a 200K car, your transmission seals will also be leaking. To replace them
you need to remove the guibo. Thus consider replacing transmission seals as
well. This is also a perfect time to swap out the transmission mounts and
refill transmission with Redline MTL.
Unless you enjoy eating dirt and crawling under the car on a cold concrete
floor (assuming you have a garage), let your mechanic do this job. I would
guesstimate 2-3 hours of labors for all of the above. 

> I do know that my transmission and engine mounts need to be
> replaced.

Wow! If both the transmission and engine mounts are truly gone, you should
(or soon will) hear all sorts of expensive noises. A 'grrrr' under breaking
is your $60 engine fan penetrating the $300 radiator. Please stop driving
the car and replace these ASAP. Start with the engine mounts (a weak point
on E30s) and remember to swap both of them even though only (passenger
side;-) mount will be sheered.

good luck,
alex f 

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