Thread: front end clunk.

2008 Pontiac grand prix base model, 3800 N/A engine L-26, 91,200 miles.

i have some modifications done but nothing serious, a intake, a pulley, flipped the dogbone bushings, did some stuff too the exhaust, really simple stuff, if any of this stuff helps.

ok enough of the chatter, i checked the forum and did some research but i am sort of stumped on this one, power breaking will not bring on the clunk, but accelerating in a straight line will, but once the clunk happens it wont clunk again accelerating only in reverse, then once you have had the clunk backing up it wont clunk again in reverse untill it has clunked again accelerating forward. it seems that the steering wheel being turned assist the clunk...

i saw this TSB on the mounts that hold the steering rack too the sub frame causing a clunk similar but this clunk happens usually when steering, my clunk typically happens when accelerating or backing up. i am also thinking a CV joint may be causing the clunk but yet again power breaking will not bring along the clunk so its hard too say.

do you guys think this can be caused buy the mounts holding the rack too the subframe or should i focus more on the CV shafts, ill also try too get ahold of a chassis ear some time.

I would inspect the engine's (lower) mount and the transmission mount, then the control arm bushings and ball joints, then the strut mounts.

My car had similar symptoms when I first bought it. All the control arm bolts were loosened up. Put the impact on them and hammered them down and it went away

thanks for your replies, i have replaced the engine mount because that was bad, checked the ball joints and control arm bushings all that jazz. will check more and tighten the strut bolts.

Also check to make your fender braces under the hood are all tight.

alright guys strut mounts look really rusty what do you think?

Is there supposed to be a pic of the rusty mounts?
So the engine mount was bad and you replaced it but the trans mount is still original? Thats a clue...

no i do not have a picture of the rusty mounts but i can get one for you, how i descovered the engine mount was bad was testing for excessive play in the CV joints and sort of rocking the tire back and forth i watched the whole engine shimmy pretty much off the dogbone bushings and transmission mount like the engine mount wasn't doing anything, just watching the whole engine shimmy back and forth... yea didn't think it was supposed too be doing that, and i replaced it and it stopped so yea, checked the transmission mount and visually it looked ok, the clunk does not appear too be coming from the area of the transmission either, the clunk is coming from passenger side...

look like this? my engine was twisting all over the place.

this is a passenger side photo of the top part of the strut mount and its still bolted too the car... its got enough rust on it i can scrape some of it off with my finger nails, it is also missing some sort of rubber ring that the drivers side has. when i turn the wheel sometimes i get a groaning noise similar sound too what the strut mounts make when the bearings are bad in them, that is what the issue probably is.


this is the drivers side

Originally Posted by Scottydoggs

look like this? my engine was twisting all over the place.

LOL! WOAH! no it wasn't that bad yet it had some cracking and stuff but the biggest thing was it didn't seem to be doing anything, it didn't look very bad but holy crap did the engine shake all over the place when i shook the wheel too check CV shaft play! replaced it with the new one and it stopped, in fact the old one hardly looked bad at all, most certainly not that bad!

that didnt clunk either. not kidding. but the engine sure did jump all over when shifted in and out of gear. in drive the whole engine twisted in the bay.

that is bar none the worst front engine mount i have ever seen, i have seen some bad ones in my day but that one takes the cake, my old 98 regal LS had one pretty bad, but that one... i am suprised you didn't hear any sort of noises, good thing you caught that, could of killed a set of CV joints or something.

your strut mounts there, hood open car running stand at the door and crank the wheel left and right, watch the center parts. if they move a lot back and fourth they are bad.

alright ill give that a try! thanks!

if they move a lot thats a clunk over bumps. at least it was in my car.

also check the rubber out under the plate under the center bolt, if it looks melted they are also shot.

usually when they go bad they tend too make a groaning noise as the bearings are shot the plate resists rotation and twists the spring, causing a groaning clunking noise when it does finally rotate.

https://www.youtube.com/watch?v=khZ16AOztT4

yup. that sound too. didnt hear that but thats the top of the strut bouncing around when the wheels turned.

it sort of makes that noise, and groans too, i think thats what the clunk is because its loudest when the wheel is turned over hard too the left backing up out of the driveway, clunks when accelerating in a straight line too so thats why i am so suspicious that is what the noise is, ill do what you suggested tomarrow morning, its dark right now so i can't see them.

if your struts pass the 3 bounce test, less then 3 bounces and they should be good still. most will only bounce 1.5 times.

but if good unless you have air tools and a spring compressor, i dont, so i took the struts off the car then took them, with 2 new strut mounts to a front end shop and had them change em, cost me like 25 bucks for the pair.