1990 240 DL Vibration

[trashy]

I mentioned this in my "hello post" regarding a project car that I just purchased. It's a 1990 240 DL with over 260,000 miles on it. I figured that I might as well post one of the relevant problems with it here to attempt to accomplish a couple of things.

1st, hopefully others more knowledgeable than I will offer tips and advice.

2nd, perhaps this may help someone else out in the future. I'm going to do my best to take pictures and document as much as possible.

The problem that I am working on right now is a vibration at speeds above 35 mph or so. The car vibrates, and feels like a tire has a bulge or a flat spot in it. Kind of a "bumpy" vibration. It gets worse until passing through speeds above around 45 mph then it starts to "smooth out". I haven't driven the car much faster than about 55 mph, and at that point it's not too bad, but at around 40 mph it's a pretty violent vibration.

My first thought was maybe a faulty tire or suspension component, but I kind of rule that out because I would think that the vibration would happen at all speeds, not just the band that I have experienced it at.

Next I considered wheel bearings and/or maybe rotor/brake related, but again, it doesn't really feel noticeable above or below the band that I pointed out.

That leads me to think that it may be drive train related. Engine rpm or gear does not seem to change anything, so I'm leaning towards universal joints, drive shaft or the center support bearing, perhaps maybe even a combination of the three. I put the car up on ramps, and crawled under to take a look the best that I can. There is some play in the drive shaft, especially near the center support bearing. I don't know or think that this is "normal", so I would like your thoughts and suggestions.

I have ordered a manual for the car that should be here within the next day or so. My plan right now is to replace the universal joints, center support bearing and any other associated parts/hardware to see if this corrects the problem.

[Retired MVS Contributor]

With the mileage and age, I would be suspicious of U-joints, except that you said it was a "bumpy" vibration...U-joints and carrier bearings set up a sort of resonance, a hum like vibration that varies in pitch with speed...So do wheel bearings...

I think you should be looking into tire balance, wheel alignment, and anything else wheel related, especially bent rims...Jack it up. spin the wheels and look for run-out...Warped rotors will show up during braking, but not during driving...

[trashy]

With the mileage and age, I would be suspicious of U-joints, except that you said it was a "bumpy" vibration...U-joints and carrier bearings set up a sort of resonance, a hum like vibration that varies in pitch with speed...So do wheel bearings...

I think you should be looking into tire balance, wheel alignment, and anything else wheel related, especially bent rims...Jack it up. spin the wheels and look for run-out...Warped rotors will show up during braking, but not during driving...

Thank your for the response. From my reading on here it seems that you really know these cars and I value your opinion on the issue.

I described the feeling as "bumpy" but there is a bit more to it, and it does change with speed (gear selection, steering input, etc. doesn't seem to change it). The amount and severity of it changes only with speed.

It does seem a little bit more "violent" when braking and coming to a stop light, but I kind of look more towards "speed" as being the issue, not the braking. When it's "more violent" is when decelerating from over 50 mph. Braking doesn't seem to change anything.

I'll look at the wheel balance and alignment as you suggest, but I suspect that something else is wrong. My reasoning is if something was wrong on a wheel, it would show up at all speeds rather than within a certain range.

[Retired MVS Contributor]

Take a look at the motor mounts, especially rhe rear one under the center of the transmission...When that mount has a catastophic failure the transmission rests on the crossmenber and transmits heavy vibration that telegraphs misleading symptoms...

Jerry

[trashy]

Well, I solved about 99% of the vibration issue, and I'm pretty pleased. Thanks to you guys for giving your input.

I finally had time to work on the car today. I figured that I would start with something simple such as removing the front wheels, do an inspection and while I'm at it, replace the bearings. Here is what I found.

1. The bearings on one side were discolored and making some noise, they definitely needed replacing.
2. Brakes and rotors look good and acceptable.
3. The passenger (right) side tie rod end was worn with a lot of play in the right wheel.
4. One of the front tires did have a bulge in it, though hard to detect.

I replaced both sets of front wheel bearings, the right side tie rod end, took the car and had 4 new tires put on it and got an alignment. The vibration is ALMOST gone, but isn't nearly as bad or dangerous as it was. Some of the other things checked and/or on my list to replace.

1. The motor mounts looked pretty good, and I can tell that they have been replaced fairly recently. I'm not going to mess with them for now.
2. Several of the front suspension bushings are worn and definitely need to be replaced.
3. The shocks and struts are worn and need to be replaced.

I feel like with the repairs that I have made and with the replacement of the shocks, struts and bushings the vibration should be all but gone.