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weird clunk

MikeGTP88

MikeGTP88

New member
well for a while when i put my car into reverse and give it gas there is a clunk that comes from the front. im not sure what is it i was thinking motor mounts. any other ideas whould be a help.
mike
 


motor mounts is very possible, cv joint could potentially clunk (not as common) slop in trans maybe, and there's always the body in the trunk
 
This is the problem on these cars from the factory gm installed a liquid filled lower engine mount. When those burst there's a clunk when that happens. But most of the times you will not see fluid on the ground because its blown back and on to the car while driving. What you need to do is get a friend and have them hold the brake while they shift from park to reverse to drive if you see any weird movemenet or you feel that the movement doesnt look right. Take the car and get the lower engine mount checked. And there is one on the right side of the transmission that could also be bad as well
 
If you run a taller oil filter, check that also. If that hydraulic mount goes bad, you engine could be sitting on the filter, stressing the oil filter housing.
 


My first thought would be the motor or trans mount. I would start there.

But LCA, CV shaft, upper dogbone mounts, etc could also be causing this...
 
19SE92 said:
I run the taller filter part number3980 or from gm pf52 i run it and its not bothered by it
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Reptile is saying that if you run the taller oil filter, and have a bad mount, it can hurt the oil filter and/or housing.

Also, I do believe the oil filter is in a different location on the 3.1s versus the 3.8
 
I had a clunk like that and it ended up being the support that was to the front of the radiator that went to the fender. After the battery was replaced it wasn't tightened down good enough.
 


If the uper dog bone monuts were loose they would break off over time. Its the lower engine mount like i said. I've changed them before and its showing the same problems
 
Zef_66 said:
Reptile is saying that if you run the taller oil filter, and have a bad mount, it can hurt the oil filter and/or housing.

Also, I do believe the oil filter is in a different location on the 3.1s versus the 3.8
Click to expand...

Correct on the location. On the 3.1 the filter is located under the exhaust manifold, at the front of the car.

And if you are running a taller filter, with a bad engine mount, when the mount collapses it will smash the filter down on the subframe which = bad news.
Sorry about the confusion.
 
Open your hood and let someone stand next to you while you do the reverse thing. This may help isolate a little better where the sound is coming from. We did this when I installed the POS ZZP upper polys. They were making a squeak that I didn't believe was coming from them. With the hood open, my son backed out of the driveway and I heard the squeak. From inside of the car and the sound I was hearing no way would I have guessed it was the polys.
 
19SE92 said:
If the uper dog bone monuts were loose they would break off over time. Its the lower engine mount like i said. I've changed them before and its showing the same problems
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:th_shakinghead2:
There you go again. making rash assumptions and judgements. have you heard his car's clunk? no. have you driven it? no. you're right in that the symptoms are similar--- but that by no means makes it the same problem. if he goes and changes the lower mounts soely based on what you say, how do you feel then? and what's this about the upper dog bone mounts breaking over time? which part? the CAST bracket, the bolts, or the stamped dogbones?? that would be something to see... come on. you're not going to break dog bone mounts, unless youre doing foolish things.
 
I've never seen the dogbones break....ever.

I'd lay money on the starter....yeah....It's gotta be the starter, I've seen it happen MANY times.
 


Reptile said:
I've never seen the dogbones break....ever.

I'd lay money on the starter....yeah....It's gotta be the starter, I've seen it happen MANY times.
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Haha...now thats funny.

But when I said dogbones, I was talking more about the rubber bushings in the dogbone itself. Mine were loose and allowing the engine to rock some. I changed these to poly ones and it doesn't move anymore. I didn't have a clunk, but given time I am sure it would have developed into one.
 
OK, right. I have seen the rubber degrade....on Abrasive's Lumina for example. That was one of those things that when you were going down the road, and let off the throttle you could feel the engine shift. He put new ones in, and it stopped.
 
I've seen the whole dog bone its self brake back when gm made them out of aluminum sp? gm had many problems why do you think they were de designed mid way thought the gen 1's run and then in the gen 2's birth..
 
19SE92 said:
I've seen the whole dog bone its self brake back when gm made them out of aluminum sp? gm had many problems why do you think they were de designed mid way thought the gen 1's run and then in the gen 2's birth..
Click to expand...

:th_scratchhead:

Specifically when?
I've owned 3 1st gen W bodies, and I've never seen an aluminum dog bone on any of them. And fwiw, if you have a dogbone that just breaks, then I would figure something else in the drivetrain could be amiss, depending on if it were cracked for a long period of time. You'd have to have severe fatigue or a bad vibration somewhere to put that much stress on the mounts.
 
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