Join Date: Nov 2002
Location: SouthEastern PA
I listened carefully to those videos. It sounds so familiar, but I can't quite put my finger on it. I have a couple questions, and a couple ideas.
1) It seems like it only makes the noise when you are on the throttle a moderate to large amount. Does it make the noise at light throttle?
2) Does it do that only in park, or also when you are in neutral or drive? When you are going down the road, or no?
3) Is your induction system stock?
1) Something hitting the floorpan, like the exhaust. It doesn't sound like cat heatshields, which I am all too familiar with. All the same, maybe it could be them too.
2) Exhaust leak (cracked header or something) ... sometimes they can sound pretty goofy.
3) Something in the valvetrain. I had a rocker arm bolt break once. The pushrod and rocker arm were just bouncing around like crazy inside the valve cover, and it sounded horrible. Kind of like your noise. But the car was definitely chugging along, and you could feel "hits" in the gas pedal. I think it's probably worth taking the valve covers off to see if a rocker arm is loose or a valve is bent or something.
4) Something stuck in your induction system. Since it seems to only make the noise when you are on the throttle pretty hard, I was thinking it might have something to do with the position of the throttle body or the amount of air getting sucked in. Like, maybe something in there is flapping around when a lot of air goes through.
5) If it only happens when at WOT, then maybe it has to do with the A/C clutch cutout. (You know, it releases the clutch when you floor it to reduce power losses.)
6) Maybe something in your tranny. It sounds a little bit like what happened to me the other day, when I was trying to get my car out of snow by rocking it. I accidentally put it in Park while the wheels were still moving, and it made a ratcheting sort of noise.
Sorry this was so wordy, but I am curious too! I hope it helps!
Owner, 1990 Thunderbird SC, white w/ gray cloth