CAEMI

There are a lot of engine vibration threads...but I can't find anything similar to mine.

I've replaced u-joints and all the running gear is tight but I still have a vibe. Last night, sitting in a parking lot waiting for SWMBO, I ran the RPMs up to cruising speed (2200 or so) and back down in 200 RPM increments and let it sit a while at each.

I noticed that I have a vibration that kind of occilates, if you know what I mean. It swells then subsides then swells then subsides in a regular rhythm at whatever RPM I selected. The timing of the cycle is maybe a couple seconds. And I have noticed the same cyclic vibration when traveling down the road...but more pronounced, like it is a bit worse under load.

I'm thinking harmonic balancer - does anybody else have a suggestion?

H8PVMT

have you checked your motor/tranny mounts recently?

Doug

CAEMI

Nope. The engine mounts are solid. What should I be looking for in the motor/trans mount??

The trans has been out of this car - was rebuilt maybe 40,000 miles ago. Shifts perfect...but the flex plate was loose when I got it. What should I be looking at under there?

freegdr

does the rpm change when you notice the vibe at low rpms

CAEMI

Hmmm. Not that I've noticed. It does not run as smooth as my V10 Ford...but I figured it just isn't a modern, V-type engine...it's never going to run as smooth as the new stuff.

When you say "does the RPM change" do you mean by a 100 RPM or 300?

The vibe I notice comes and goes in a cycle of about 2 or 3 seconds. That seems like a short time, but 3 seconds when you're sitting still with the engine at 2000 RPM seems longer.

If anybody can do so, start your engine and run the RPMs up to 2000 and hold it there. Tell me if you feel a little vibration that sort of "occilates" or cycles from smooth to vibration every few seconds. That's what I've got.

freegdr

the balancer could be wobbleing there no very costly and its one of those parts that when it goes you aint going home with out it

freegdr

mine went about a year ago just at the end of my street i did notice a little less shacking in the motor when i replaced it mines an 89 so i expected some vibe ,you stated the motor mounts were solid by that do you mean in good shape or solid mounts

CAEMI

I really need somebody to do the same test and see if some vibes are "normal". I don't think they are...but the balancer LOOKS fine and doesn't appear to wobble.

I know they're cheap, but I hate replacing parts just because I suspect them. Even cheap, they ain't free and neither is the time to do the work.

CAEMI

The mounts are in good shape - they are M.O.R.E mounts and were replaced a few years ago when the originals crapped out.

When your balancer went, did it go all of a sudden or just slowly die?

freegdr

are the mount soft rubber like factory or harder that will give vibe you did not feel before and the balancer just came apart in a split second the outer ring came off with the grooves for the belt

H8PVMT

I replaced my mounts with Brown dogs and there is off and on a noticable vibration which is due to the higher quality mounts but is normal

CAEMI

Does your vibration cycle in and out like every three or four seconds?

H8PVMT

I would say yes, but I'll pay more attention to it today

freegdr

off and on vibration could be ac compressor cycleing it does this even with the heat on worth looking into...

CAEMI

That's an idea. So I did it and, no, it's not the AC compressor...mine actually doesn't work.