I just bought an '88 GXL with 90,000 miles and in beautiful looking condition. I am concerned about vibration from the engine. Is it normal for the engine to vibrate when revving in neutral? It varies according to RPM, but really vibrates the wheel etc. at certain points, like 3,000 rpm. What's going on??? HELP!

 

By the way, it vibrates through the rpm range whether the clutch is depressed or not - no difference. Serious vibration - worse at certain rpms. I thought rotary's had less vibration - this hums the whole car!

 

Check your U-Joint and your tranny mount, as well as your engine mounts.

I had pretty bad vibration, a new transmission mount solved my problem.

The FSM and Haynes manual describe how to check these things.

Now, my car didn't vibrate when the clutch was pushed in (disengaging the engine from the tranny) when the car is in neutral (and the clutch is out) the gears are still spinning around in there and bad mounts can cause vibration.

If when you push the clutch in your vibration stops I would definatly look at the trans mounts and U-Joint.

Hope this helps.

 

You posted this extra info as I was submitting... I would still check all those mounts (maybe more likely the engine mounts now if you still have bad vibration with the clutch in...)

 

Thanks for reply. It makes no difference if the clutch is in or out - vibration is the same, so I figured it wasn't the input shaft on the tranny or anything. I didn't know if there was anything in the engine that could cause imbalance. Maybe you are right and the motor mounts are shot. All I can say is that the vibration is pretty bad 2500-4000 rpm. It doesn't vibrate at idle, and higher rpms smooth it out. Scares the hell out of me that I bought a big problem, but the car was never abused, always garaged, owned by a mature woman who bought it new.

 

Your problem sounds a lot like the problem I had, except mine would calm down when i push the clutch in. Maybe you have a combination of bad motor and tranny mounts. The tranny mounts are easy enough to check. Just get under the car and pry the tranny against the mount part. It should have very little play... I think there is a similar check for the engine.

 

make sure your wheels are torqued down properly.

check engine mounts and tranny mounts. also check driveshaft for play. i wouldn't be surprised if the driveshaft was going bad.

this is pretty much universal advice for any rwd car with a vibration problem.

 

Vibration in neutral rules out the whole drive line.
With the clutch disengaged, all that's left is the engine, flywheel & pressure plate.
It could be a non-issue, for example worn out shift bushings will make the shift rattle even in a perfect engine.
It may be something simple like some slung clutch material caught in the pressure plate, or a broken engine mount.
It could messy, like a kludged rebuild, EG: an S5 flywheel & counterweight bolted to an S4 engine, or an S4 & S5 rotor in the same engine..

 

The only time I remember having a 3K vibration was when I took the A/C compressor off (doing an "uninstall") while the steering pump was still on there. After about a week of that crap I mounted the compressor back onto the bracket and the vibration went away. Strange, huh? Good news is, once I removed everything (A/C AND power steering equipment & bracket), the vibration never returned....