Rattle in exhaust
Thread Starter
Racer
Joined: Feb 2002
Posts: 352
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From: Langhorne Pa
Rattle in exhaust
I have a 408 with high flow cats. I can hear a rattle at idle. It's even louder when I rev the engine. Sounds like it's coming from the catalytic converter. What are some symptoms of at cat going bad? Anyone else have a different idea of what I should look at?
The high flow cats have been on the car for 2 yrs and just less the 5k miles. If it's the cats I'll probably run catless from here on.
Thanks in advance.
The high flow cats have been on the car for 2 yrs and just less the 5k miles. If it's the cats I'll probably run catless from here on.
Thanks in advance.
Pro
Joined: Nov 2003
Posts: 716
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From: Long Island City NY
Before you start taking stuff off your car, check out the flanges which connect your rear exhaust to your cat. These are notorious for going bad; as it did on mine. I started the rattle and started to really get worried. I was especially noticable when I sort of lurched forward and when the car was in a high gear at a low speed (read: working the exhaust/engine). In Houston, I had a guy who diagnosed the problem and fixed the problem for $40. He found two welds were broken and charged me $20 per weld. It solved the problem totally.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Jack the car up mon all 4's and use a rubber mallet to bang the exhaust system and listen for the noise. I agree with SJ. The welds are prone to breaking. The mallet will help find the noise as will a CLOSE inspection of the entire system.
BC
BC
Instructor
Joined: Nov 2001
Posts: 225
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From: Beaverton Oregon
Something else to check is the two springs that provide tension to supporting the exhaust pipes. One of mine wasn't under any tension, because of the way the pipe was routed, and it would rattle quite a bit. If that's the case, just bend the hanger a little bit to put tension on the spring, and that should make the rattle go away. When your car is not running, and you slam the door, and hear it rattle, that's one way of knowing it's one of those springs.
Jason
Jason
Thread Starter
Racer
Joined: Feb 2002
Posts: 352
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From: Langhorne Pa
Thanks for the help guys. I'll do what you all sugggested. I just got the car back from Cartek last week and had been thinking that it something was overlooked and not tightened properly. Since the noise was getting worse my new thought was that maybe it was the cats. I'll let Cartek straighten this one out.
