Under the valve cover
Thread Starter
Instructor
Joined: Jan 2007
Posts: 157
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From: Austin TX
Under the valve cover
I have a 71 350 and just had side pipes put on. It seems to sound like a lot of air coming out of my left valvue cover. It's kind of a puff puff puff or puttering sound. It sounds like the noise is coming from underneath the valvue cover and NOT around the header gasket, so I am thinking this is not an air leak at least at the header connection.
Any thoughts?
Any thoughts?
Drifting
Joined: Jul 2004
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From: Kissimmee fl
Finalist 2021 C3 of the Year - Modified
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St. Jude Donor '07
The OBX are made in China, however most here that have installed them have favorable comments about them. That said, I would bet there is still an exhaust leak at the flange. It does not take long on a running engine to burn and blow out a gasket.
There should be nothing under the valve cover to give you that same sound. Any leak of the valve cover would be blowing oil.
You might try retorquing the flange bolts as they often work loose as the gaskets burn in.
There should be nothing under the valve cover to give you that same sound. Any leak of the valve cover would be blowing oil.
You might try retorquing the flange bolts as they often work loose as the gaskets burn in.
Thread Starter
Instructor
Joined: Jan 2007
Posts: 157
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From: Austin TX
The OBX are made in China, however most here that have installed them have favorable comments about them. That said, I would bet there is still an exhaust leak at the flange. It does not take long on a running engine to burn and blow out a gasket.
There should be nothing under the valve cover to give you that same sound. Any leak of the valve cover would be blowing oil.
You might try retorquing the flange bolts as they often work loose as the gaskets burn in.
There should be nothing under the valve cover to give you that same sound. Any leak of the valve cover would be blowing oil.
You might try retorquing the flange bolts as they often work loose as the gaskets burn in.
Drifting
Joined: Jul 2011
Posts: 1,697
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From: Syracuse NY
Start your car when its COLD. While its running, take your finger and place it near, above and around the suspect noise. You WILL feel the jet of HOT gas coming out of your exhaust flange. You may want to double up on your exhaust gaskets. (Yes, put 2 gaskets on one side.) (How Ive run my last 350 and my 454)
Emphasis on doing this with a COLD engine. 1) the metal hasnt expanded to seal up any small gaps yet and 2) well, its gets real hot real quick and you dont want to burn off your fingers.
Emphasis on doing this with a COLD engine. 1) the metal hasnt expanded to seal up any small gaps yet and 2) well, its gets real hot real quick and you dont want to burn off your fingers.
Thread Starter
Instructor
Joined: Jan 2007
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From: Austin TX
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Thread Starter
Instructor
Joined: Jan 2007
Posts: 157
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From: Austin TX
Start your car when its COLD. While its running, take your finger and place it near, above and around the suspect noise. You WILL feel the jet of HOT gas coming out of your exhaust flange. You may want to double up on your exhaust gaskets. (Yes, put 2 gaskets on one side.) (How Ive run my last 350 and my 454)
Emphasis on doing this with a COLD engine. 1) the metal hasnt expanded to seal up any small gaps yet and 2) well, its gets real hot real quick and you dont want to burn off your fingers.
Emphasis on doing this with a COLD engine. 1) the metal hasnt expanded to seal up any small gaps yet and 2) well, its gets real hot real quick and you dont want to burn off your fingers.
However, since there has been a leak, I am now wondering if the gasket it burned or blown out in that particular area. if that's the case, then I would say they are liable to take it off and fix it free of charge since this has only been about a month or two months max.
Melting Slicks
Joined: Jul 2006
Posts: 2,269
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From: Salmon Arm, BC
Yes, I have seen just the bottom part of a exhaust gasket blow out. It looks just fine when inspecting from the top, but placing your fingers underneath the flange you will feel exhaust gasses.
I feel there is no need to double up the gaskets.
After you replace the gaskets, it's a good idea to go around the header bolts and snug them up for the first week ( or several weeks if you just drive it occasionally.) You will know when they are good because they're not loose anymore.
I feel there is no need to double up the gaskets.
After you replace the gaskets, it's a good idea to go around the header bolts and snug them up for the first week ( or several weeks if you just drive it occasionally.) You will know when they are good because they're not loose anymore.
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
i have the sweet thunder inserts and they have a fluttering sound at idle, thought you might have the same issue
take a lighter with a long reach and run the flame around the header gasket and see if it tries to blow the flame out anywhere. beats running your hands around it.
take a lighter with a long reach and run the flame around the header gasket and see if it tries to blow the flame out anywhere. beats running your hands around it.
Thread Starter
Instructor
Joined: Jan 2007
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From: Austin TX
i have the sweet thunder inserts and they have a fluttering sound at idle, thought you might have the same issue
take a lighter with a long reach and run the flame around the header gasket and see if it tries to blow the flame out anywhere. beats running your hands around it.
take a lighter with a long reach and run the flame around the header gasket and see if it tries to blow the flame out anywhere. beats running your hands around it.
Team Owner
Joined: May 2001
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From: Western NY
The headers do NOT have to be completely removed to replace an exhaust gasket. All you need to do is remove the flange bolts, pullout the (bad) gasket, slip in a new gasket, and re-torque the bolts.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Try these metal gaskets. Best gasket I've ever used.
http://www.summitracing.com/int/part...6012/overview/
http://www.summitracing.com/int/part...6012/overview/
Thread Starter
Instructor
Joined: Jan 2007
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From: Austin TX
Even with side pipes? Seems like you would at least remove the collectors, so there is some wiggle room with the headers.
Team Owner
Joined: May 2001
Posts: 87,294
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From: Western NY
Worst case, you might have to loosen the bolts that secure the side tubes to the car. The gaskets are only 0.050-0.060" thick, so you don't have to move the headers back all that far.