Light thump from under front floorboards of '96 Deville.

[wchenry]

I am hearing a light thump-like sound coming from under the front floor boards of my '96 Caddy DeVille whenever I hit bumps or drive over uneven pavement. I've replaced the front sway bar links and the struts (Arnott conversion set). The sound persists. I can find nothing loose in the exhaust system. Any suggestions on where I should go from here?

[airmike]

If the exhaust is too close to the floor board it wouldn't really need to be loose to hit. Even a tight exhaust system has a little flex in it. Just a thought. If you suspect a spot you could wedge something soft in there and see if it goes away, but don't leave it there, you don't want it on fire.

[KHE]

Check the stabilizer bar mounting bushings. With the car on ramps, use a pry bar and attempt to move the bar. If it moves within the bushings, the bushings are bad.

[rockfangd]

here is a few things to consider. I have an issue on my 96 also but mine is when I accelerate or hit bumps just right. there is a cross bar that bolts under the car and the exhaust can touch it just enough to make noises. but looking underneath it probably wont be touching.

second. check your subframe bushings. there will be 4 at the rear. 2 driver side, 2 passenger side. if the bushings are worn or rusted that will definately cause the problem youu describe because they mount right near the floors

[KHE]

Another thing to check is the exhaust clamp near the resonator which is downstream of the catalytic converter. I had a strange rattling noise on my '97 STS and the original wire type clamp had totted through and slid down the pipe enough to rattle against the crossbar.

[Logan]

It is possible that what you are hearing is the cradle mounts moving some.

By design the cradle mounts can only be snugged up so far...and rubber can loosen up over 15 years. Pops, snaps, and creaks is what you will hear.

[BodybyFisher]

Check your engine mounts also