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TyeGrady
05-20-2015, 12:26 AM
Hello,

I have a 1993 Thunderbird SC, AOD transmission, approximately 230,000 miles on it. I love this car and I would hate to give it a premature end because of something I can't figure out. The car has been developing this rattling sound from under the car and I havn't been able to pin down what it is. I'll outline everything I know about it so far.

The noise occurs at idle and between 1000-2000 rpms. It also happens when the car is parked and the transmission is in park. This means it is not the brakes or anything related to the wheels or rear differential.

The noise gets worse when I give the car mild to hard acceleration.

I don't notice the noise when I am going highway speeds and the rpm's are above 2000.

I am pretty sure that it is not an accessory causing the noise. I pulled off both the main serpentine belt and the secondary belt between the crankshaft and the jackshaft and ran the engine momentarily. The noise was still there when the car was idling. The A/C compressor is fairly new, the alternator is fairly new, the power steering pump is fairly new. The only accessory not changed out recently is the water pump. I also checked the crankshaft to see if there was any play in it while I had all the belts off and there wasn't any movement.

The transmission does need to be rebuilt to fix the slipping of the overdrive gear, but the transition between gears is smooth and it does not jerk or surge when shifting gears.

I also have a recording of the noise.
https://www.youtube.com/watch?v=kqme5wSIfSo

The video starts out with the car in parked idle, then I switch the car into drive and rev the engine near the end of the video. The instrument panel should be visible in the video except when I move the phone out the window to get the noise better.

Any advice or info on what else I can check or look at to see or figure out what it is would be greatly appreciated. I've been scratching my head over this for a few weeks now and the noise is only getting worse.

RyGuy
05-20-2015, 12:40 AM
Is it the exhaust moving or the heat shield under the exhaust moving?

KMT
05-20-2015, 12:41 AM
Sounds like maybe a rattling heat shield on one of the converters.

sam jones
05-20-2015, 04:25 AM
Good morning

After watching the video I would put the car on jacks. Remove the starter.

Inspect the AOD transmission at the 6 o"clock opening for the (4 ) torque converter loose and or missing nuts/studs.

With the starter remove check the visible area of the flex plate for cracks and or missing material.

Use a small magnet at the AOD 6 o'clock position and "sweep" for any metal debris.


Good luck.

SCarSC
05-20-2015, 07:26 AM
Sounds like when my catalytic converter material broke up and bounced around...at one point it finally blew out of the back and no more noise...you can get under with a tube in your ear and listen to each one to narrow it down...mine was passenger side.

Rob89SC
05-20-2015, 08:01 AM
Heat shield on converter