Exhaust odor - leak or normal?
Thread Starter
Cruising
Joined: Jan 2006
Posts: 14
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Exhaust odor - leak or normal?
I often notice a strong exhaust smell in the cabin when I slow down quickly after moderate to hard acceleration. I can't see any damage to the exhaust system and it sounds tight.
Could it be due to rich exhaust leaking out the manifold and being drawn under the hood into the cabin air intake? I know some of the C5s had leaky manifolds. Or is it just rich fumes from the tail pipes being backwashed around outside the car to the cabin air intake?
Could it be due to rich exhaust leaking out the manifold and being drawn under the hood into the cabin air intake? I know some of the C5s had leaky manifolds. Or is it just rich fumes from the tail pipes being backwashed around outside the car to the cabin air intake?
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
A new C5 Corvette never has OR should never have an exhaust smell in the cabin! If you smell exhaust,,you have an issue. Sure,,,,If you have the window open and the wind is at your back, you may smell some. If you smell it when the windows are closed, that is not good.
There are a few places where exhaust fumes can leak from the engine under the hood:
A.I.R. Manifold Flanges or piping
Manifold to Mid Pipe flange
Manifold to engine joint
Theres a cabin pressure equalization vent in the rear of your cabin. It behind the carpet on the drivers side right above the small storrage compartment. Make sure that it seals properly and is not damaged.
I thought my header exhaust system was gas tight. I seafoamed the engine and when I cranked it up, I found out that I had a significant leak at the A.I.R. flange on the passengers side. The small gasket between the flange was damaged and a small piece blew out. Lots of smoke came out that joint. A new gasket fixed that Right up.
BC
There are a few places where exhaust fumes can leak from the engine under the hood:
A.I.R. Manifold Flanges or piping
Manifold to Mid Pipe flange
Manifold to engine joint
Theres a cabin pressure equalization vent in the rear of your cabin. It behind the carpet on the drivers side right above the small storrage compartment. Make sure that it seals properly and is not damaged.
I thought my header exhaust system was gas tight. I seafoamed the engine and when I cranked it up, I found out that I had a significant leak at the A.I.R. flange on the passengers side. The small gasket between the flange was damaged and a small piece blew out. Lots of smoke came out that joint. A new gasket fixed that Right up.
BC
Thread Starter
Cruising
Joined: Jan 2006
Posts: 14
Likes: 0
BC, thanks for the suggestions. I visually inspected the system some time ago and used a length of garden hose to listen for leaks at each gasket and flange weld, but all I found were pinhole gaps in the factory welds around the flanges at the rear ends of the midpipes. I wouldn't expect them to allow much gas to leak out or to be the source of the smell back in the cabin. I have Corsa mufflers, so there shouldn't be much back pressure after the cats.
I'll have to take a closer look now at the AIR system, bracket welds and the equalization vent.
Pete
I'll have to take a closer look now at the AIR system, bracket welds and the equalization vent.
Pete
Last edited by Retserof; Dec 27, 2009 at 11:11 AM.
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From: Honolulu HI
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
I'm a motor head from WAY BACK when cars didn't have cats. I guess were all use to a better smelling exhaust. 
BC