A little rattle..big bucks?

[tlong]

I can usually get very close to how much a noise will cost to fix on a car.This one has me stumped. This is a pretty loud rattle from under the car.

It happens ONLY under acceleration at 1600-1800 rpms regardless of gear (auto). Sometimes it ain't there. I have Corsas. We put it on a lift and banged around for 45 minutes. No cure.

Won't rattle in neutral at rest or coasting, only with the gas, only at 1700 rpms. It stopped when shifting up for a fraction of a second, then resumed indicating drive train under load.

U-joint? Trans bracket? Motor mount? Cat? Heat shield? This one is tough. Care to guess? I assure you the resolution will be posted right here.

Thanks,

The Rattler

 

[MBDiagMan]

Unfortunately noises and vibrations are somewhere between very difficult and impossible to troubleshoot over the internet.

What does it sound like? Does it clank? Does it ring? Does it thud?

From your description it sounds like it could be a heat shield or something resonant. Maybe a bad motor mount or something is causing it to happen under certain torque conditions.

Sorry I can't help any further,

 

[tlong]

I scoff at my brothers attempting to get help about a noise here. But it's fun to try!

Metal to metal, only under torque, a few hundred rpms. There's 15 gallons in a 10 gallon bucket under there. Guess I'll put it on a four point lift and run it up in gear. It's annoying to not be 100% but she's 10 years old and this is the first sign of arthritis.

 

[Moonunit 451]

I'll bet on the Cat.

 

[AdvancedAutoCC]

Cat or heat shield most likely... as stated before, it is hard to diagnose over the Net.

 

[nyernga]

I'll bet on the Cat.

same here. Replaced mine two months ago and the symptoms were similar.

Or maybe it's your vettes way of telling you to stay off the dragon....

Len

 

[Robertwav1]

My guess...heat shield or cat also. I had re rivet my heat shields twice cause of that. They were just the slightest bit loose and would vibrate at a certain RPM. Interesting to know what you find.

 

[jsinga]

If you make sure it's not the heat shields I'd go with the cat. I finally found mine when the brick in a pre-cat broke up and plugged EVERYTHING up. Try the end of a hammer handle right on the front of the cats and see if you find out anything.

JS

 

[nyernga]

And if you DO remove the shields to re rivet them do what I did. Go to home depot's welding area and buy the material that welders use to protect surrounding areas from heat damage. Cut a piece the size of the shield and attach it with some high temp silicone before riveting it back. You be amazed at how much cooler the floorpan is.

Len

 

[Achilles]

My guess...heat shield or cat also. I had re rivet my heat shields twice cause of that. They were just the slightest bit loose and would vibrate at a certain RPM. Interesting to know what you find.

Same here!