Mechanics

POSSIBLE CLUNK IN FRONT END?

1999 Pontiac Montana • 280,000 miles

I have a clunk in the front end of my Montana. Only occurred when turning right. Suspected frame sway bar bushings. Disconnected sway bar. Drove around for a few days. Tried to duplicate the clunk noise. No noise. So, when ahead and replaced sway bar frame bushings and end links. Took for a test drive, now it doesn't take much to make the clunk, and its 10 times louder. What could it be? There didn't appear to be any cracks in the sway bar, but I could have missed it. Thank you in advance.
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Mrdenny
October 15, 2011.



If the noise will occur when the vehicle is standing still, you have the advantage of being able to search underneath while a helper turns the steering wheel. The first suspect would be the upper strut mounts. You can find that by reaching over the top of a front tire and wrapping your fingertips lightly around one of the coils on the spring. When your helper turns the steering wheel, you should feel the spring turn smoothly with the wheel and tire. If it binds, then snaps free, that mount is binding and must be replaced.

When you turn, one corner of the vehicle actually lifts up a little and the other side goes down. With the anti-sway bar disconnected, there's no pressure on the lower control arms so the upper mounts could have turned more freely. Same with the lower ball joints. You might have just reduced the tension on the noisy part by disconnecting the links.

There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.

Caradiodoc
Oct 16, 2011.
Hi there. Thank you so very much for your reply. Right after I posted my question, I went outside to check for any cracks or breaks in the sway bar. Found nothing. Then was going to disconnect the sway bar again, and deal with the body roll while trying to find out what the issue was. Before doing this, I decided to drive the left front wheel onto a car ramp. I made it make the noise. So, while on the ramp, I got underneath to check the sway bar again. Found nothing. Checked control arm bushings once again. AND, found that the left front vertical bushing is completely gone. Never noticed it before, but with the left stuffed into the wheel well, the control arm was forced into the frame, making it obvious. So, new bushing on its way, and I'll be changing it in the days to come. Thank you once again!

Tiny
Mrdenny
Oct 16, 2011.
Don't know why I didn't think of that right away. I've heard about worn control arm bushings quite a bit in the last few years. Very happy you found it.

Caradiodoc
Oct 16, 2011.