Obnoxious Front End/LH/Steering Clunk 2000 LeSabre, How Loud Might A Bad CV Joint Be?

[pcmos]

My 2000 LeSabre has an aweful clunk in the Lefthand Front area on the vehicle that occurs while turning in parking lots or under slower driving conditions with the wheel cocked pretty far to the left usually. For example as I turn my wheel hard to the left to get into a parking space I would expect to hear a very loud metallic clunk, loud enough that people walking past the car look to see what I ran over. The sound is absolutely obnoxious and I see a lot of people have already complained about it on this forum, but no one has written that the problem was definatively solved by a given repair. Many seem to suggest the CV axle as the source, but I was always under the impression that this was more of a "cyclic clicking or knocking sound" that would be heard while turning a bend in a road for example. Not a one-time metallic clap. Now while driving straight down a very bumpy road at say 25 MPH, and by bumpy I mean pot hole bumpy where the wheels are constantly rumbling over the pavement, I can hear an abnormal metallic chatter coming from the LF area on the car. My mechanic at the dealer always seems to be deaf when I ride with him, so are his "electronic ears" or sensors, but I get the odd feeling that they are either witholding information or they don't really care two hoots about my problem. They have taken apart everything under the sun because I have an extended GM warrenty on the car and GM keeps authorizing their work, but they put it all back together again with the same parts and lots of greese. Now in all fairness they did claim to replace my "magnasteer" rack and pinion, and supposedly the left hand outter tie rod and left hand spring seat, but I havn't crawled under to confirm that the work was actually done. Once again I never get billed for any of this because they can't find the problem, so they may or may not be doing everything they say. When the front end of the vehicle is lifted off of the ground so that the tires don't contact the pavement, I can turn the wheel back and forth with the engine running and its dead silent. If I drop the weight of the car onto the control arms but keep the wheels off the ground and try the same thing with the engine running, its also dead silent. As soon as I let it down off the stands so that the car is sitting normally in the same spot on the tires, the sound returns right there. So I am assuming that the frictional forces posed by the tires contacting the ground are putting a load on some bad part that pops or acts up under such conditions. But the sound is extremely elusive and almost impossible to pinpoint, even when I get down and listen to it with someone else turning the steering wheel for me. VERY VERY STRANGE, so far from what I have read this is the most anyone has seriously tried to track this down on the car, and I am persistant enough that I'll eventually find it, even if I have to replace everything myself. But I would really appreciate anyone's input, even if you have a good story about this problem on your car. LoL, most people who experience this probably need a support group if you're at all into your car, because it is one of those sounds that makes a mechanically minded human being cringe!!! BAD ENGINEERING GM, LETS HIRE SOME REAL ENGINEERS NEXT TIME

[pcmos]

FINALLY after days of tearing things apart on my own, Ive found the problem. There are a series of frame bushing mounts that attach the front engine frame to the body. On the front corners of the square shaped frame, there is one mount per corner, and on the rear two corners there are actually two mounts per corner, an inner and an outter. The inner most drivers side mount is the source of all the clunking and crunching sounds. Basically where the lower rubber bushing buts up against the bottom of the engine frame there is a tappered hole in the frame and an oppositely tapered raised metal piece cast into the rubber mount itself. The tapered metal part of the rubber mount doesn't fit into the tapered hole in the frame under normal hand pressure. However when you put the mount assembly together and torque the bolt to the specified 141 Ft-Lbs, the metal on the rubber mount press fits itself into the hole in the metal frame, creating a very tight fit, similar to a control arm bushing. When I dropped the frame down and examined the fit of all of the mounts, the inner drivers side mount fell right out of the hole in the frame. In fact either the mount or the hole in the frame is worn or damaged because there is no way that the two pieces could ever press fit back together. What this means is that the lower rubber bushing is free to flex around in the hole in the frame and hence the loud popping and crunching sounds. Since my car is still under a GM warrenty, I am going to write up an entire report detailing my discovery for my friendly GM service advisor, and see what their reaction is. If not for the fact that I am concerned that the frame is damaged, I would simply buy another 10 buck rubber bushing and put it on, but I don't want to attempt a repair if it turns out the problem is with the frame. I will let the dealer worry about that, since my deductable is only 100 bucks he can pull the whole engine out to replace the frame if thats what he has to do, but he can only smack me with a 100 dollar repair bill. We'll see what happens, if the dealer treats me like dirt i'll take a 10 dollar gamble on the fact that the mount is simply worn out. I am writing all of this out so that anyone who has a similar problem can hopefully get right to the source of the trouble without doing all the diagnostic work ive had to do. Anyway, I'll keep everyone posted.

[pcmos]

Ok, this morning I put the car back up on the jack in my garage again. This time I completely removed the inner drivers side engine cradle mount (referred to as the #2 mount by GM). I then put the whole assembly back together and torqued all of the bolts to the factory specified 141 ft-lbs. As soon as I started lowering the vehicle off of the jack stands I knew I had the problem nailed, because with the mount in place it would have popped and groaned as it was being lowered. I then VERY cautiously drove the car around the block for a while without the mount. There are actually sounds that I used to hear in the car that I didn't even know were related to this mount until I drove it today, THE CLUNK IS GONE!!! Now I have a new mount assembly (all components of the #2 mount) on order with my dealer and I intend to install it as soon as it comes in on Tuesday. Unfortunately I should mention that there is still some chance that the problem is actually with the frame itself. If the hole in the frame has become badly erroded the new mount will not press fit into the hole as it should and it will probably clunk again. But for now I am being cautiously optimistic that its simply an old mount. I'll keep posting until I have the problem licked, once again I hope this makes it to someone who has the same problem.

[creslevi]

Thank you, What a great job you have done, and thank you for all your efforts in keeping the forum updated.
Rick

[sallisonbrown]

Originally Posted by pcmos

Ok, this morning I put the car back up on the jack in my garage again. This time I completely removed the inner drivers side engine cradle mount (referred to as the #2 mount by GM). I then put the whole assembly back together and torqued all of the bolts to the factory specified 141 ft-lbs. As soon as I started lowering the vehicle off of the jack stands I knew I had the problem nailed, because with the mount in place it would have popped and groaned as it was being lowered. I then VERY cautiously drove the car around the block for a while without the mount. There are actually sounds that I used to hear in the car that I didn't even know were related to this mount until I drove it today, THE CLUNK IS GONE!!! Now I have a new mount assembly (all components of the #2 mount) on order with my dealer and I intend to install it as soon as it comes in on Tuesday. Unfortunately I should mention that there is still some chance that the problem is actually with the frame itself. If the hole in the frame has become badly erroded the new mount will not press fit into the hole as it should and it will probably clunk again. But for now I am being cautiously optimistic that its simply an old mount. I'll keep posting until I have the problem licked, once again I hope this makes it to someone who has the same problem.

Good job, and thanks for keeping us informed.
Don't you think it would be a good idea to replace BOTH rear mounts while you are at it. Having the #2 worn so badly could have caused the right side one to wear funny and when you replace #2 then the right side one will be torqued differently. Just a suggestion! For an additional $10 what will it hurt!

[pcmos]

Yeah, but before I spend any more money I want to make sure that the problem isn't with the frame. Actually the total cost of the rubber pieces which are the wear parts turned out to be more like 15 bucks. However, just to be safe I am replacing all of the hard metal parts including the bolt on the #2, so the total cost with all of the parts was more like 40 dollars. If the repair works well I think i'll go ahead and replace the rubber pieces on all 5 other mount assemblies. In thinking about your suggestion I may consider doing the rubber on the 4 corners and then replace the full metal set on the other #2 mount. Frankly, all of them are worn pretty badly, but the metal parts appear to be in good condition. I just don't want to be any deeper into my wallet until I know for sure I have the clunk fixed, because if I need to have the frame replaced its going to cost me 100 bucks under my warrenty policy. I don't have an engine hoist of any kind so unfortunately I have to quit in my repair process if it turns out to be a frame problem.

[sallisonbrown]

Originally Posted by pcmos

Yeah, but before I spend any more money I want to make sure that the problem isn't with the frame. Actually the total cost of the rubber pieces which are the wear parts turned out to be more like 15 bucks. However, just to be safe I am replacing all of the hard metal parts including the bolt on the #2, so the total cost with all of the parts was more like 40 dollars. If the repair works well I think i'll go ahead and replace the rubber pieces on all 5 other mount assemblies. In thinking about your suggestion I may consider doing the rubber on the 4 corners and then replace the full metal set on the other #2 mount. Frankly, all of them are worn pretty badly, but the metal parts appear to be in good condition. I just don't want to be any deeper into my wallet until I know for sure I have the clunk fixed, because if I need to have the frame replaced its going to cost me 100 bucks under my warrenty policy. I don't have an engine hoist of any kind so unfortunately I have to quit in my repair process if it turns out to be a frame problem.

Good point! Good luck with the rest of the job. Thank somebody that you were able to get that extended warranty. Keep us posted.

[pcmos]

Ok, FINALLY I NAILED IT. I am happy to announce with significant confidence that the clunk sound is fixed. I went ahead and replaced that #2 frame mount assembly on the driver's side of the car. Everything went according to plan, and after driving the car I knew the problem was fixed. I was so happy I gave it a nice fresh wash and wax today. I'll put out another final update later in the week when I am absolutely sure it is fixed, and i'll also provide some more details on how the repair progressed, because there are some thing I need to mention, but it's wayyyy too late now and I need sleep.

[stuzman]

Originally Posted by pcmos

Ok, FINALLY I NAILED IT. I am happy to announce with significant confidence that the clunk sound is fixed. I went ahead and replaced that #2 frame mount assembly on the driver's side of the car. Everything went according to plan, and after driving the car I knew the problem was fixed. I was so happy I gave it a nice fresh wash and wax today. I'll put out another final update later in the week when I am absolutely sure it is fixed, and i'll also provide some more details on how the repair progressed, because there are some thing I need to mention, but it's wayyyy too late now and I need sleep.

Hi pcmos,

I wanted to let you know that I had the same problem except it was on the passenger side. With your detailed post and email, this problem has been resolved. Thanks for all of the help!!!!

Terry