front right grinding/knocking sound

[tomstir]

hey guys,

I have a 1996 850 that I love and it has been making strange noises recently. I thought the noise was the hatch not sealing properly...but last weekend I was driving with my wife and she said the noise was definetly coming from the front right. It only makes the sound over small bumps or imperfect roads...I cannot hear it at higher speeds....it's is probably still there but I cannot hear it. The noise doesn't seem to be associated with the steering....does not appear when jerking the wheel back and forth. I have done some research on this site and inspected the main items that others have said could be the problem.

I moved/wiggled the strut top and could only get it to move about 2 degrees...about as much as a piece of rubber bushing would give. I inspected the sway bar end links and they appear normal...no smushed bushings, the lower motor mount appears ok...I put the jack under the oil pan and when I went to raise it the whole car lifted. The wheel doesn't move like there is a failed bearing....and doesn't make any noise when rolled while in the air. The only problem that I saw was the right tie rod end dust cover had failed and there was a blob of grease on the outside of the cover. I shook the tie rod and couldn't get it to mimmick the sound I hear while driving....plus the sound doesn't appear to be associated with the steering (at the same time) as much as it is with small bumps or imperfections in the road. I drove through a pretty smooth empty parking lot and couldn't get the sound while cranking the wheel back and forth.....only when going over small imperfections.

Because of the sound when going over bumps I think it would be associated with the struts....but they appear ok...old but ok. With the failed dust cover I'm thinking that that is the culprit....but it doesn't make the sound while turning......I don't want to waste money or especially time throwing parts at it......although I am secretly hoping to have to "replace" the suspension.



Any tips or wisdom?

[funbuffalo24]

Just wondering, when you first take off from a stop, or reverse from a driveway, etc., do you hear a small knock/bump as well? I'm asking because so far, your issue sounds like similar sounds I've experienced from having a bad control arm ball joint in the past.

If your tie rod boot is torn to the point of weeping grease, I'd definitely replace that as soon as possible. I'd also suggest using the subframe instead of the oil pan as a jack point.

[Ozark Lee]

I have seen the bolts on the sway bar end links cause the same sounding problem. The bolts tend to bind unless the suspension is equalized. You can get the torque spec right on the money but once the car hits the ground again the bolt remains a bit loose. Have someone bounce the fender while you grab each end of the links, if there is a loose one it will be obvious when you have it in your hand. Even if that isn't the problem you can put a big check mark next to that one and take it off the list of possible causes.

...Lee

[tomstir]

thanks for the suggestions,

funbuffalo-- I have only heard a knock when first taking off once...although I have heard a loud knock when turning left into a tight parking space. I only jacked up on the oil pan as a test for the engine mount.

lee-- I will test the end links when my wife gets home

thanks

[Ben850]

That explanation of symptoms has all the indications of the lower right engine mount by the crank pulley. It is an inexpensive piece and less than an hour of simple work. It is pictuerd in my avatar photo.

There are write-ups in the repair forums.

Here is a comparison of the colapsed one and a new one. I would not suggest jacking up the engine by the oil pan as a test.
If it has never been changed it is likely shot.
Good luck.

[tomstir]

Ben,

thanks for the reply/photo's. I just assumed that if the mount was broken then there would be a large separation when jacking up the engine...is this not so? I only raised it a small amount and didn't notice any gaps. When looking at the mount from underneath it appears to be full....kind of like a balloon...I thought they were full of some kind of "shocking" liquid and if broken would not appear the way it does.

thanks

[Ben850]

Ben,

thanks for the reply/photo's. I just assumed that if the mount was broken then there would be a large separation when jacking up the engine...is this not so? I only raised it a small amount and didn't notice any gaps. When looking at the mount from underneath it appears to be full....kind of like a balloon...I thought they were full of some kind of "shocking" liquid and if broken would not appear the way it does.

thanks

No, you will not "see" the separation, but you will feel it because the engine will effectively be sitting on the subframe. This is a solid rubber between metal. There is a safety bar that is not seen that does not allow total separation.

[tomstir]

I switched out the tie rod and took it for a spin around the block....did not hear the annoying sound anymore.....I will drive further tomorow (my baby was sleeping and I didn't want to go very far) to check it our for sure. While in there I looked the mount below the crank pulley and it looks fine. I hope this fixed it!!

I'm still not sure why/how the sound was being made...if it was the joint....I moved it around once out and could not get it to make any sound other than some of the grease escaping from the boot.....maybe I can't mimic 1000 pounds of force with my hands.

[Matty Moo]

Ben,

thanks for the reply/photo's. I just assumed that if the mount was broken then there would be a large separation when jacking up the engine...is this not so? I only raised it a small amount and didn't notice any gaps. When looking at the mount from underneath it appears to be full....kind of like a balloon...I thought they were full of some kind of "shocking" liquid and if broken would not appear the way it does.

thanks

No, you will not "see" the separation, but you will feel it because the engine will effectively be sitting on the subframe. This is a solid rubber between metal. There is a safety bar that is not seen that does not allow total separation.

You know it. It's that distinct feel and sound. I can diagnose a blown side engine mount within 2 seconds of starting the car.

[tomstir]

I took the car for a spin today with the family (more ears) and as soon as I started to move the sound came back.......UUUGGGHHHHH!!!!! We drove to the store and I could hear it but not as much as before....what did I change to make the sound go away partially? It's like the old sound was more loud and this one was more muffled/quieter. Maybe the sound is coming from the inner tie rod? But turning the wheel doesn't seem to be associated with the noise. When I had the car in the air and the tire off I placed the jack under the control arm and raised it to mimic a load and pushed and pulled on what I think was everything that could be making the noise and nothing sounded weird.

When I drove the car home there wasn't any odd sound....what happened in the two hours sitting in the parking lot? Maybe something had to settle? But what? Very odd! I guess when I drive it to work on Monday it will be a good test.

If it was the engine mount (which looks fine) wouldn't the noise be made at idle? Or at least when revving the engine..wouldn't the engine shake or vibrate more than usual? I would think the engine would lean more to the passenger side too?

Maybe it is the strut and I can't mimic the sound without duplicating the quick force uneven pavement would have when driving 20 mph. I jumped on the right and left sides making the car wallow and all I could hear was the friction of the shock moving up and down.

Any suggestions?

tomstir