C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

EGR Valve question

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Old Nov 1, 2009 | 10:17 AM
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Default EGR Valve question

I just purchased an 86 coupe and it has a very bad leak in the EGR valve. The previous owner tried to "fix" the problem as you can see in this photo. I beleive that this is causing the car to idle roughly at times. Also, the AIR pump has already been removed and there are no inspections where I live. Am I better off replacing the Valve or just eliminating it?


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Old Nov 1, 2009 | 12:48 PM
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That is not the EGR valve, it is the cross over pipe that comes from the exhaust manifold to the intake manifold on a 86.
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Old Nov 1, 2009 | 01:28 PM
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Originally Posted by John A. Marker
That is not the EGR valve, it is the cross over pipe that comes from the exhaust manifold to the intake manifold on a 86.
sorry for the wording. Isn't it also know as the EGR Pipe?

This looks an awful lot like it. Its listed on corvette central as an EGR Pipe

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Old Nov 1, 2009 | 05:33 PM
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Thats it, if this is leaking it will cause it to idle poorly..I don't think the repair that I see in the picture is going to be airtight so thats probably your problem..The EGR helps by allowing recirculated air into the combustion chamber that reduces temps by as much as 500 degrees. Without it the car can experience timing ping and performance reduction..My advice is if you can , keep the EGR functional...WW

Last edited by WW7; Nov 1, 2009 at 05:37 PM.
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Old Nov 1, 2009 | 05:39 PM
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Not meaning to hijack but what is the best sealer to use on the threads where the pipe screws into the exhaust manifold on my '96?
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Old Nov 1, 2009 | 06:14 PM
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Originally Posted by lgolson
sorry for the wording. Isn't it also know as the EGR Pipe?

This looks an awful lot like it. Its listed on corvette central as an EGR Pipe

Thats it!
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Old Nov 1, 2009 | 08:02 PM
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From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
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Originally Posted by John A. Marker
That is not the EGR valve, it is the cross over pipe that comes from the exhaust manifold to the intake manifold on a 86.
Chevy in their wisdom put the EGR valve under the intake manifold on the L98 engines
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Old Nov 1, 2009 | 10:08 PM
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Here is a tip that may get you by until your new pipe arrives.

Basically this is a thin piece of aluminum which was cut/sheared to the same shape as one of the riser/pipe gaskets (except for the center hole of course) that go on each end of the EGR pipe (pipe in the above picture). Holes were punched where the mounting hardware goes....use one of your existing gaskets as a templet. This is basically a D.I.Y. EGR block off plate that mounts between the existing EGR manifold riser and the existing EGR pipe....you do still need to use the existing gaskets also. No exaust gets up into the riser at all with this puppy in place. Great piece for quick testing of possible "stuck open" EGR issues.....doesn't generate a trouble code either.

Top Side:


Bottom Side:

Last edited by engle1147; Nov 1, 2009 at 10:27 PM.
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Old Nov 3, 2009 | 10:18 AM
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Originally Posted by WW7
Thats it, if this is leaking it will cause it to idle poorly..I don't think the repair that I see in the picture is going to be airtight so thats probably your problem..The EGR helps by allowing recirculated air into the combustion chamber that reduces temps by as much as 500 degrees. Without it the car can experience timing ping and performance reduction..My advice is if you can , keep the EGR functional...WW
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