Engine Vibration?

[baileydog]

I have been trying to track down a vibration that occurs in the car at specific RPM ranges, especially under harder accelleration. We put the car on the hoist and ran it in gear..the vibration starts at 1300 RPM, goes away at 1800 comes back again at 2300 to 2700 and on and on. We have tracked it down to a vibration in the engine/transmission (it occurred when the car was in neutral, and you revved it up...but it is more apparent when in gear), the tech figured it was either the harmonic balancer or the torque converter (BMW apparently sent out a bulletin, on this occurring with the converter, the bearing or the bushing wearing?)

540i - 5speed auto

Have any of you ran across this problem, of engine vibration?

Cheers

[632 Regal]

unless the vibration is obviously BAD these V8s do oscillate at different RPMs. Mine has a decent one at 1800 which feels like a miss but goes completely away at 2000 etc etc...same as you

you cannot perfectly balance a 40 degree 8 cylinder engine to be perfect at all rpms, there has to be compromise somewhere.

[Kalevera]

The v8 harmonic balancers DO go bad, but the engine would likely stall or sputter at anything above ~ 2700 rpm.

Sure you don't have a collapsed engine or trans mount?

best, whit

[632 Regal]

Great reminder Whit! Bad mounts really can transmit some vibration.

[baileydog]

I did check both the transmission and the engine mounts, and they all seemed to check out.
I did replace the transmission output shaft bearing and the bearing halfway down the driveshaft, so it seems to me that there has been some problems in the past with the driveline.
Does it make any sense that the torque converter has a bad bearing or bushing, thereby creating a vibration. BMW did have a bulletin out mentioning a failure here.

,

[mattyb]

the centre bearing and flex disc are due at about 200k anyways. who did them and was the shaft put back on correctly? how did u check the tranny mounts and the engine mounts? if u dont lift em all the way up, especially the engine mounts u wont know. my money is on the engine mounts before heading into other complicated stuff. if the engine mounts havent been done for a while then its not going to hurt to do them. they are cheap and quick to do and then start looking for a vibration if there is still one.

[baileydog]

We checked the engine mounts at my local (they are pretty good, I get to be there at all work) the mounts were checked with a bar and prying.

I will however change the engine mounts, the tranny mounts were done when the flex bearing was done.

Thanks bud,

[E34 530]

the centre bearing and flex disc are due at about 200k anyways. who did them and was the shaft put back on correctly? how did u check the tranny mounts and the engine mounts? if u dont lift em all the way up, especially the engine mounts u wont know. my money is on the engine mounts before heading into other complicated stuff. if the engine mounts havent been done for a while then its not going to hurt to do them. they are cheap and quick to do and then start looking for a vibration if there is still one.

You beat me to it. I definetly agree with mattyb. My car only has 58k and I just replaced the guibo and center bearing. Even if you recently replaced the guibo CHECK IT AGAIN. I replaced mine in July of 05 and by November of 05 it was ripped to ****. I think the problem was (1) the guibo was a cheap Malaysian part and was a POS or (2) the center bearing was so bad that it managed to shred the guibo to pieces again. I had the same kind of vibrations that went away after a certain RPM was achieved. It doesn't seem likely that it's the guibo or center bearing, because I originally thought it was the engine or trans. mounts also. Hope this helps you out a little.
-Andrew

[mattyb]

u can drop the front plastic protective plate and under the front of the sump it is safe to put a block and then jack it right up from that point. its the only way to really see what the mounts are doing. i am just an amatuer and the first time i looked at the mounts i though they looked bloody brilliant. my father in law , whos a mechanic, then showed me much to my horror that when he jacked it up the mounts were completely separated. just a thought. good luck anyway

[Bill R.]

jack the motor up like that

u can drop the front plastic protective plate and under the front of the sump it is safe to put a block and then jack it right up from that point. its the only way to really see what the mounts are doing. i am just an amatuer and the first time i looked at the mounts i though they looked bloody brilliant. my father in law , whos a mechanic, then showed me much to my horror that when he jacked it up the mounts were completely separated. just a thought. good luck anyway