Right front clunk

[rockfangd]

Hi all. I have had a clunk in the right front of my Deville for as long as I can remember. I think it had it when I bought the car.

Anyway I have given up a few times trying to figure out the cause, and I am starting to pull my hair out because it sounds louder now but I just cant detect the exact problem.

Here is what it does.

If you hit a bump on the right side only it clunks

I cannot feel it in the steering wheel.

Drives straight and wheel is straight

If you hit a bump(speed bump for example) where both front tires contact, nothing happens

It is specific to the corner only.

I have replaced

inner and outer tie rods. (inner had play when I bought the car)

I removed and rebushed the lower control arm last year when I repaired the strut rod portion.

I replaced the balljoint when I had the control arm out

I replaced the hub assembly (noisy but no play)

I replaced the sway bar links

And lastly I replaced the whole strut with a donor unit (basically to see if anything would change).

Nothing has solved the noise

I have jacked it up by the body and checked for play, also inspected the subframe bushings which look surprisingly good for the year and miles

I jacked it up by the control arm and checked for play. Nothing.

I have tried bouncing the front end, grabbing the wheel and checking while on the ground. Nothing at all.

I am down to thinking it can be

sway bar bushings(I would think it would be noisy with both sides though) I inspected the swaybar and found no play or cracks

Subframe bushings worn. I would not know how to find out if this is the problem.

Replacement strut just as bad as old one. An expensive gamble for a new unit.

I am baffled that as much noise that it makes that I cannot find the cause. I thought for sure that when I fixed the strut rod bushings last year that that would have cured it, but not with my luck.

And another thing that has been driving me nuts. The clock is running faster than usual. It gained 9 minutes in a month. This is very common to these but I dont know why. Usually it will be 10 minutes fast after about 6 months but not lately. Maybe I will have to talk to the dealer on this one.

Thanks all in advance for any insight

[adallak]

That is very strange that the right side clunks only separately. Have you tried to apply brakes slightly before hitting a bump? If it has something to do with loose brake pads, there will be no clunk.

[rockfangd]

That is very strange that the right side clunks only separately. Have you tried to apply brakes slightly before hitting a bump? If it has something to do with loose brake pads, there will be no clunk.

Thanks. Brakes applied or not it is the same. I actually notice it the most with going around corners with bumps and hitting manholes, etc...

I might also add I have had the car aligned at least 4 times in my ownership and nobody even caught the strut rod bushings. It seems quick money is the best for places. And I had mentioned this to every shop and nothing was found.

The thing I am afraid of is finding out the hard way someday.

[jndnaps]

I have a clunk in my right front too when I hit some bumps, but I put it off as needing new struts. I really do need new struts.. I had the front end checked and everything is good but the struts. Was thinking of replacing with passive struts, but I don't drive it a lot so I've been letting it go.. Also, my clock runs fast too.. I never really kept track of by how many minutes or months..

[Cadillac Jim]

If it doesn't happen when both front wheels hit the same bump, it's somewhere in the stabilizer bar, its bushings, or its links. It could be something hitting somewhere due to the stabilizer bar not being exactly centered.

I had something similar and I had the stabilizer links changed. It didn't go away. A few months later I had them changed again. The first guy had charged me for the parts and labor but never touched the stabilizer links, which were bad. Then, the problem went away.

[KHE]

The stabilizer bar bushings are the prime suspect in my opinion. I had one side that was worn on my STS but the other side was tight. Get the car on some ramps (so the weight of the car is on the suspension) and take a pry bar and move the stabilizer bar while watching the bushings and other components. I will bet you will find the problem.

Even if the stabilizer links were replaced, one could still be bad.

[rockfangd]

If it doesn't happen when both front wheels hit the same bump, it's somewhere in the stabilizer bar, its bushings, or its links. It could be something hitting somewhere due to the stabilizer bar not being exactly centered.

I had something similar and I had the stabilizer links changed. It didn't go away. A few months later I had them changed again. The first guy had charged me for the parts and labor but never touched the stabilizer links, which were bad. Then, the problem went away.

Thats nice. I know mine got done lol because I did them. I will definately look into the swaybar bushings. What have I got to lose

I have a clunk in my right front too when I hit some bumps, but I put it off as needing new struts. I really do need new struts.. I had the front end checked and everything is good but the struts. Was thinking of replacing with passive struts, but I don't drive it a lot so I've been letting it go.. Also, my clock runs fast too.. I never really kept track of by how many minutes or months..

There are TSB(s) that were supposed to have addressed the problem but it seems to be just a coverup. both my 96 and 97 have the same problem but the deville runs faster. Maybe because it gets driven daily.

I have issues. If I know it is not right I have to fix it otherwise it will drive me nuts til I do

[Cadillac Jim]

If you want a pro mechanic's solution at a WalMart price, get an audio-only cordless baby monitor and put the microphone against whatever you suspect is clunking under the hood. Listen to the monitor, with headphones if necessary, while you drive the car. Move the microphone until you find it.

[Texas Jim]

If you want a pro mechanic's solution at a WalMart price, get an audio-only cordless baby monitor and put the microphone against whatever you suspect is clunking under the hood. Listen to the monitor, with headphones if necessary, while you drive the car. Move the microphone until you find it.

That is a great idea....

I will remember that...

[Cadillac Jim]

Thanks. If someone identifies a particular make and model and cites successful use of such a thing, or a Karaoke microphone, or whatever, it can go on our How-To page. I'll keep that in mind the next time I'm in Best Buy or whatever. I'd *love* to post a wav file of a supercharger doing its stuff, sort of a trapped-squirrel-under-the-hood viewpoint.

[KevinW]

I would suspect the stabilizer bushings/insulators too. Assuming they are intact and there's no physical evidence of metal-to-metal contact anywhere, they are still capable of causing a temperature-sensitive clunking type noise in the front suspension over sharp-edged bumps, mostly noticeable at lower speeds while they are not drowned-out by road and wind noise. It seems the noise is generated by the slipping of the bar against the urethane material (degraded or contaminated); there's normally no relative movement, and application of a lubricant will have temporary effects, though this might be useful as a diagnostic aid if a change in character is observed.

As for the clock gaining time, I believe there's a TSB concerning an updated BCM that includes a fix for a programming error... or maybe you're just driving too fast in one direction.

[rockfangd]

Thanks. I believe there was more than 1 and my car has been done. They told me there is nothing that can be done without replacing the bcm, etc... and hope the problem goes away

[PAUL T]

I had my stabilizer bar break under one of the bushings. I had that sound also for a long time until I drove onto an inclined driveway at an angle to where the right side started up the incline first. There was a hard clunk and I got out and checked and that side of the bar was just hanging there. It had been cracked and took a long time to finally break.

[KHE]

Thanks. I believe there was more than 1 and my car has been done. They told me there is nothing that can be done without replacing the bcm, etc... and hope the problem goes away

The clock function is stored in the PZM. The fix is to replace the PZM.

[KevinW]

It appears the TSB uses 'Body Control' and 'Personal Zone' interchangeably:

RADIO CLOCK GAINS TIME (INSTALL UPDATED BCM) #63-90-15 - (Oct 23, 1996)

SUBJECT: RADIO CLOCK GAINS TIME (INSTALL UPDATED BODY CONTROL MODULE) MODELS: 1996 CADILLAC CONCOURS, DEVILLE, ELDORADO AND SEVILLE

BUILT PRIOR TO THE FOLLOWING VIN BREAKPOINTS:

MODEL VIN BREAKPOINT ===== ==============

CONCOURS/DEVILLE TU305353 ELDORADO TU619572 SEVILLE TU836232

CONDITION:

SOME OWNERS OF THE ABOVE LISTED VEHICLES MAY COMMENT THAT THE RADIO CLOCK MAY TEND TO GAIN TIME. UP TO 2-3 MINUTES A MONTH MAY BE GAINED DEPENDING ON THE AMBIENT TEMPERATURE.

CAUSE:

THE CLOCK TUNING CIRCUITRY IN THE BODY CONTROL MODULE (PZM) IS NOT PRECISE ENOUGH TO MAINTAIN THE REQUIRED CLOCK ACCURACY OF +/- 1 MINUTE A MONTH.

CORRECTION:

INSTALL AN UPDATED BODY CONTROL MODULE (PZM) USING THE FOLLOWING PROCEDURE.

IMPORTANT: THIS SERVICE PART CONTAINS AN INSTALLED PROM. DO NOT OPEN THE PART AS INDICATED IN THE SERVICE MANUAL. THIS BULLETIN SUPERSEDES THE PZM INSTALL/CONNECT PROCEDURE AS INDICATED ON ALL PREVIOUS BULLETINS.

REMOVE OR DISCONNECT

1. COMFORT FUSE FROM THE TRUNK COMPARTMENT FUSE BLOCK.

2. REAR SEAT CUSHION AND SEAT BACK.

3. INSPECT BODY CONTROL MODULE (PZM).

- IF SERVICE PART NUMBER IS 16247212 OR 16238499 THE PZM HAS ALREADY BEEN UPDATED FOR THIS CONCERN AND SHOULD NOT BE GAINING TIME; RECONFIRM CONCERN WITH OWNER BEFORE REMOVING PART.

INSTALL OR CONNECT

1. BODY CONTROL MODULE (PZM).

2. REAR SEAT BACK AND SEAT CUSHION.

3. COMFORT FUSE IN TRUNK COMPARTMENT FUSE BLOCK.

4. REPROGRAM PZM OVERRIDE PZS33 ACCORDING TO THE FOLLOWING VALUES:

E = 6 = ELDORADO K = 4 = SEVILLE KSP = 5 = CONCOURS/DEVILLE

5. STORE VALUE:

- HOLD THE FRONT "DEFROST" AND "AUTO/ECON" ("A/C" FOR ANALOG IPC) FOR APPROXIMATELY 5 SECONDS UNTIL THE DISPLAY FLASHES.

6. CYCLE IGNITION.

PARTS INFORMATION:

BODY CONTROL MODULE (PZM) P/N 16238499

PARTS ARE EXPECTED TO BE AVAILABLE OCTOBER 21, 1996.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION LABOR OPERATION NUMBER DESCRIPTION TIME =============== =========== ===============

N4800 COMPUTER (CONTROL), BODY - USE PUBLISHED REPLACE LABOR OPERATION TIME.

FIGURES: 00 ATTACHMENTS: 00

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.

COPYRIGHT 1996 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.

[rockfangd]

That is one of the TSBs. My 97 does the same thing too though. But I dont remember if they had a tsb for that year.

Also I am having trouble as nobody seems to list swaywar bushings for my Deville. Weird. Guess I will have to keep trying

[JohnnyG]

I had a clunk similar to what you describe in my 1999 STS. I solved it simply by drenching the upper strut tower opening with a good rubber lube. I never really expected that to solve my issue when I was doing it, so it was a pleasant surprise. I can't tell you the brand of rubber lube that I used (and couldn't when I wrote my first post on the issue) since I got the lube in an unmarked container from a buddy that worked as an auto detailer.

I CAN tell you that it was a blue liquid in a trigger spray bottle that they used on all kinds of rubber and vinyl surfaces at the time. My guess would be that it was heavy on silicone content.

I figured at the time that it couldn't hurt and I was at wits end with the clunk. Neither could I find find ANYTHING loose or worn underneath the car.

[rockfangd]

so wait you pulled the plastic cap off and sprayed it in the upper part of the mount? Never thought of that. I did do the strut bearings though

[JohnnyG]

Sorry for the late reply. I did write a reply several days ago, but it didn't get posted for some reason, probably my fault.

Anyway, there was no plastic cap on my '99 STS, and checking my 2008 DTS the plastic cap only covers the threads of the top strut mount, so there is no need to pull that. The lube was squirted down around the top mount opening so that it would get to the outside of the big rubber doughnut which is the upper mount isolator. My reasoning was that the rubber was chafing or rubbing on the shock tower enclosure causing the noise.

As long as rubber lube is used, I don't see how this can harm anything and it might just work for you as it did for me.

[rockfangd]

I had my stabilizer bar break under one of the bushings. I had that sound also for a long time until I drove onto an inclined driveway at an angle to where the right side started up the incline first. There was a hard clunk and I got out and checked and that side of the bar was just hanging there. It had been cracked and took a long time to finally break.

wow. how did I miss that post. Thats nuts. I rarely see a bar break like that. Apparently a stress crack that spread. I would hope that if mine were broken I would have found out when I did my links.

Anyone have any explanation as to why I cannot find any kind of listing for front swaybar bushings? I have never run into this problem before

[Cadillac Jim]

The problem is that you need to know the diameter of the stabilizer bar for your particular car. Once you have that you can get them from Rock Auto, the dealer, or one of the GM parts suppliers.

[PAUL T]

My car had front damage on that side before I bought it. I would say that was why it was cracked and much later broke. The sway bar bushings on my 97 Deville were a pain to get to. It is like they were installed before the cradle was put in the car. I also had one bolt that froze and had to be heated to get it out.

[Cadillac Jim]

I found the 1996 Deville front stabilizer bar bushings on GMPartsDirect: CLICK HERE

They are a bit pricey, at $20 apiece, and they are different left and right. I would use the "Check Parts Applicability by VIN" feature at checkout to make sure that they fit my car. The Concours has a different parts catalog on Rock Auto (which does NOT list the stabilizer bar bushings) and if the stabilizer bar is different, the busings will be different.

[KHE]

Have you pried up on the sway bar while watching the bushings to see if there was any movement of the bar inside the bushings?

[rockfangd]

Ok. Just for the heads up I am putting this on a back burner for right now. I just got my Seville out and it needs some immediate attention so I guess the Deville gets a little break. I will update this when I get into it further.