Trans noise

[kroberts]

After about 750 trouble free miles, my swapped E30 suddenly developed an ugly transmission noise. The trans is a ZF out of a 98 M3. I installed a ltw flywheel kit (Fidenza) from BavAuto, it included a new clutch, pressure plate, T.O. bearing.

I thought it was a bad throwout bearing & I still hope that is the case. If I understand the T.O. bearing diagnosis correctly, the noise should go away when the pedal is depressed. However, my trans makes noise when the clutch is out. I dont know how to describe the noise, it's sort of a grind/rattle. I can hear it the instant I engage the starter. If I let the car idle in neutral, it really makes a racket. When I push in the clutch the noise is almost completely silenced. I can just barely feel it in the shifter.

It seems like the problem developed in an instant. I had driven the car earlier in the day and everything was fine. I got in to head home and the noise was so bad I had it towed instead. I'm going to pull the transmission soon. Is a bad throwout bearing fairly obvious?

Thanks in advance for any troubleshooting help you can offer.

[jlevie]

If the noise is only present when the transmission is in neutral and the clutch is engaged, it may be input shaft rattle. Which is frequently a side affect of a lightweight flywheel. Before pulling the transmission I'd suggest having an experienced BMW tech listen to the noise.

[kroberts]

Would the fact that the noise began suddenly indicate a component failure or impending component failure?

[jlevie]

If it is input shaft rattle, it probably isn't a sign of impending failure. But there are other possibilities, which is why I suggest getting an expert opinion.

[kroberts]

Generally speaking, is this the sort of thing I can limp to my local indie shop? it's about 5 miles away. Or should I see If the tech I know would stop by after work?

[jlevie]

It is impossible to judge that without hearing the noise. The safe bet would be to have the car towed to a shop or have the tech go to the car.