Vibration at 2500rpm

[john97obw]

Hey folks. This is an extension of a thread I started before. I've searched and read tons of threads on this, but I'm wondering if anybody has solved their issues of rpm specific vibration/shudder.

 

My shudder happens at 2500 rpm. While driving, I can't really tell where it is coming from, though it still happens with the car in park and definitely feels like it's coming from the engine compartment. Many others have found the problem to be the drive shaft u-joints. Would the shudder still happen with the FWD fuse in? And shouldn't I expect that this would have gotten progressively worse over the past 40K? How about engine mounts?

 

I can also detect a little shimmy in the crank pulley. I suspect a little vibration from the engine could be exacerbated by worn out struts/springs.

 

 

Some history (copied from previous thread):

Bought @ 50k. Front crank seal @110k. New timing belt, but no pulleys or pumps HG and rear main seal @ 145K. The rear seal was leaking pretty badly. The HG hadn't caused any overheating, but there was oil residue in the coolant overflow and a hydrocarbon test indicated the leak. Since the engine was being pulled, I decided to go ahead with the head gaskets and new timing belt--this time with new pulleys and water pump.

 

Knock sensor at about 155k. Passenger front wheel bearing not long after that.

 

Blew cam seals at 165k (Guy who did the HG and crank seals didn't bother with cam seals. He no longer works on my car.) Again, new belt and front main seal. New plugs and oem wires right after this.

 

I've had to do a couple brake jobs on it. Last year, the caliper slide was siezed on each caliper front and back. They were all replaced then and regreased this summer.

 

Early this summer, I took it to a reputable shop who ran the diagnostic tests. All sensors were within spec.

 

CV joints about a month ago.

 

I sometimes worry about the engine internals because I had oil leaks for so long. I was vigilant about oil levels, but there has been more than one time that I've had to add more than a quart.

 

The thing is, I can live with the shudder--or at least I have been doing so for about 2 years now. It just bothers me that it does it when it seems like it should be an easy fix. I waver between constantly shopping for a replacement and vowing to get it to at least 200k.

[john97obw]

Oh yeah. 97 OBW. 173,000 miles.

[brus brother]

What brand CV joints/transaxles did you use?

I seem to remember a running post a while ago about just this sort of vibration that was pegged to the transaxles.

[crash321]

You would have a knocking noise if the crankshaft was moving around like you descibed. I would first suspect the engine mounts and trans mounts. You described the the vibration still happens while parked so this is where I would look first. The engine and trans move as one when the engine is torqued so looking at both mounts may yield an answer. If those are good, you should look at the harmonic balancer on the front of the engine. They do wear out (believe it or not) and is something most people don't look at. Good Luck.

[Fairtax4me]

I suspect a little vibration from the engine could be exacerbated by worn out struts/springs.

Struts and springs will have no effect on a vibration that occurs even if the car is sitting still. Your vibration is engine or transmission related, and that is as far as you need to look.

 

You mentioned play in the crankshaft pulley. The crank pulley as previously stated is a harmonic balancer. It has two sections separated by a layer of rubber. If the harmonic balancer goes bad, it will create a vibration.

Get some white out, and make a line across the face of the crankshaft pulley. Let it dry, then start the engine. If the harmonic balancer is bad, it will be obvious very shortly because the line will break at the rubber layer. The two sections will be spinning with each other, but not as the same speed. The outer section will spin slower because it has added drag from the belts and accessories.

[john97obw]

Thanks for the replies. I know the cv joints are not the problem since the vibration predates the new axles.

 

I'll check the mounts carefully,Crash.

 

Interesting idea, Fairtax. I'll definitely try that and report back.

[john97obw]

Well, I tried the white-out trick--actually I used a nice bright purple nail polish that made my car look like a tramp. No difference in movement between plates.

 

I had my wife rev the engine at a steady 2500 rpm and the alt belt shook prett violently. It smooths out above and below 2500. Didn't have a chance to do much more, but I'll be borrowing a torque wrench at the very least.

 

I konw I need to check the torque, but is it still likely that the harmonic balancer is going bad if it turns out the bolt is not loose?

Edited October 12, 2009 by john97obw

[Fairtax4me]

Well the bolt is only what holds the pulley on. If the pulley is indeed loose, then it is probably damaged now. There should be no "play" in the crankshaft pulley though. I can envision something that looks like it has been beat with a sledge hammer under neath of that pulley.

 

The alternator belt shaking would indicate that it is loose, or that something is causing it to become loose at that certain speed.

Have you ever tried removing the belts entirely and seeing how/if that affects the vibration?

Edited October 13, 2009 by Fairtax4me

[Olnick]

At this point I think you'd be wise to remove the bolt and take the harmonic balancer off, if possible. There may be hidden damage. Check the balancer, the key and especially the keyway slot in the crankshaft--look for excessive wear and deformation.