hey everybody! Im having a problem with my '90 5.0 mustang with the auto. tranny. When I first drive the car to work in the morning it's ok for about 10 minutes without any noise but AFTER about 10 minutes and then on for the rest of the day, there is a rattle under the car when I try to accelerate. My first guess is obviously the tranny. I believe I've heard a similar noise when I was having probs with the tranny on my mustang, But the car still shifts very smoothly and all...it's just that the hard I try to accelerate the louder the rattle is....and then when I let off it reduces down to the point where I cant here it all? I guess what I need to know of this is an indicator that my tranny is shot? Or is it possible to save it?
Rattling from underneath my Car!
- Thread starter shlby123
- Start date
Consider your cats. I don't know if it happens in factory cats, but I had a Steeda/Moreflow (or some such brand) 2.5" cat h-pipe and the cats went South with a major rattle. The ceramic honeycomb guts broke up inside there, and when it happened I thought sure I'd dropped a valve. It really did sound like a rocker arm broke or something. And like yours, it was heat and speed sensitive. Could just be time for a new h-pipe.
MahFiVeOh
Founding Member
SamSnyder said:
I had one of my cats go bad also, it sounded just like an engine knock. Just crawl under and "rattle" the exhaust and see if you can hear the noise.
I really want to but the catch to it is, is that the noise will only start once Im in gear, and moving down the road.
What I did was take the car through a very narrow pass yesterday in a neighborhood, had somebody drive while I tried to take a sound/video clip with my digital camera, but after 3 unsuccesful passes at trying to get the camera to pick up the noise so I could show ya'll what it sounds like, the camera would only pick up wind! It's been so tricky....And since it only makes that noise after 10 minutes when i start driving it during the day...it's baffling me...how can I diagnose it, if I cant get a real sound clip, and I can get the noise when the car is at a standstill?
What I did was take the car through a very narrow pass yesterday in a neighborhood, had somebody drive while I tried to take a sound/video clip with my digital camera, but after 3 unsuccesful passes at trying to get the camera to pick up the noise so I could show ya'll what it sounds like, the camera would only pick up wind! It's been so tricky....And since it only makes that noise after 10 minutes when i start driving it during the day...it's baffling me...how can I diagnose it, if I cant get a real sound clip, and I can get the noise when the car is at a standstill?
Are your motor mounts in good shape? Otherwise, the motor and drivetrain can torque-load when you're in gear, and if there's an interferance issue, it can make noise.
I'd also check heat shields.
Good luck.
I'd also check heat shields.
Good luck.
Not sure what heat shield you're talking about -- the outer skin on the cats? Don't know about that. It's been a few years but as I recall, when my cat first started rattling it was minor, and I actually squeezed the one that was rattling, which actually stopped the rattling for a while. My thinking was that if the honeycomb inside was loose, I might wedge it in place by squishing the cat body slightly. What the heck, I knew it was f***'d up anyway. And it worked -- for a while. I seem to recall wedging a block of wood between the cat and the floorpan, and jacking up underneath the cat to compress the outer shell. It worked for a while but it ultimately failed completely, with a rattling sound like a busted rocker arm. However, I was sure it was the cat before I started smashing it up. I ultimately just got a new h-pipe.
fivespeedsteed
20+ Year Stangneter 
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