Exhaust manifold noise?
Thread Starter
|
Member
Joined: Aug 2001
Posts: 57
Likes: 0
From: Charlottesville, VA
Exhaust manifold noise?
Guys:
I have had a problem recently develop: I have a noise that sounds like rushing air coming from my engine compartment. It sounds like it's coming from the exhaust mainfold, though I can't be sure. It only happens while the engine is cold. It happens mostly after I let off the gas (i.e. while I'm shifting). Does anybody have any experience with this kind of noise? What could it be? I'm hoping just an exhaust leak somewhere as I'm getting ready to replace the exhaust system. Can my heads suffer damage if I don't fix this problem soon?
Other info that may or may not help: Truck is a '95 302 5spd w/97k miles. I'm getting 16.5 mpg highway with no overheating and no steam coming out of tailpipe, and no water in oil (paranoid about a cracked head). Heat sheild on Cat is not loose.
Any help is appreciated.
Oh yeah, should I post this in the engines forum as well?
later
scott
I have had a problem recently develop: I have a noise that sounds like rushing air coming from my engine compartment. It sounds like it's coming from the exhaust mainfold, though I can't be sure. It only happens while the engine is cold. It happens mostly after I let off the gas (i.e. while I'm shifting). Does anybody have any experience with this kind of noise? What could it be? I'm hoping just an exhaust leak somewhere as I'm getting ready to replace the exhaust system. Can my heads suffer damage if I don't fix this problem soon?
Other info that may or may not help: Truck is a '95 302 5spd w/97k miles. I'm getting 16.5 mpg highway with no overheating and no steam coming out of tailpipe, and no water in oil (paranoid about a cracked head). Heat sheild on Cat is not loose.
Any help is appreciated.
Oh yeah, should I post this in the engines forum as well?
later
scott
Senior Member
Joined: Aug 1999
Posts: 389
Likes: 0
From: Keller, TX
Cracked exhaust manifold
These are notorious for cracking. Could have it replaced w/ stock replacement (go to a salvage yard, dont pay factory prices for a restrictive chocking manifold).. OR, get some shorty headers for = or less price than factory new pricing. You'll get 3-4hp out of it and it will be cheaper.
Thread Starter
|
Member
Joined: Aug 2001
Posts: 57
Likes: 0
From: Charlottesville, VA
Thanks guys!
Thanks for the input, guys. It is a weird problem as the noise only occurs when the temp is cool (less then 40 or so) AND the engine is cool. I kind of suspected a cracked exhaust manifold.
I took it to the dealer (the local one has a great service dept.) for help in diagnosing....of course a warm front came through, temp went up to 50 and the noise didn't happen. I'll probably take it back if it gets colder soon.
Anyways, I can pick up manifolds for $50 from the graveyard, so I'll try that if they prove to be the problem.
later
scott
I took it to the dealer (the local one has a great service dept.) for help in diagnosing....of course a warm front came through, temp went up to 50 and the noise didn't happen. I'll probably take it back if it gets colder soon.
Anyways, I can pick up manifolds for $50 from the graveyard, so I'll try that if they prove to be the problem.
later
scott
Thread Starter
|
Member
Joined: Aug 2001
Posts: 57
Likes: 0
From: Charlottesville, VA
Finally have an update:
After much more searching with the stethescope, it turned out to be a bearing in my smog pump. Replaced the pump and haven't heard it since (knock on wood). Thought I'd pass it along in case it happens to anybody else. Man, it sounded just like hissing from a manifold, too--had everybody stumped.
later
scott
After much more searching with the stethescope, it turned out to be a bearing in my smog pump. Replaced the pump and haven't heard it since (knock on wood). Thought I'd pass it along in case it happens to anybody else. Man, it sounded just like hissing from a manifold, too--had everybody stumped.
later
scott