Exhaust doughnuts

Clone TIE Pilot

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Aug 14, 2011
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Can exhaust doughnut gaskets be reused if they ard still in good shape or are they a one time use crush part? Is it possible that if they do leak, could that affect O2 sensor readings at idle due to reversion? I am running some old TES headers which have the O2 sensors in the driver side collector upstream but near a doughnut flange. I have a weird issue where my fuel mixture at idle is good in park but lean in drive and wondering if it could be false reading due to exhaust leaks? I already replaced the exhaust gaskets between the heads and headers so the seals there are good.
 

CopperNick

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Feb 20, 2018
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Possible. Something to try might be coating them with some Permatex High Heat Copper RTV, or the High Heat Spray Bomb version that is used on head gaskets for some applications. If the doughnut is slightly deformed, the foo-foo juice could just be enough to fill in the dent or dimple and give you a sold gasket face to butt up against the flange.

There is also a product which is a type of exhaust gasket cement, comes in a tube, sort of a grey color. Apply a thin even coat of that to the gasket surface of the doughnut and let it set and then stuff the "nut' back and see if that works.



Nick
 
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69hurstolds

Geezer
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Jan 2, 2006
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I have successfully reused donut gaskets after inspecting them for wear/cracks and general condition. If you have a new one on hand, there's no reason not to use it, but if you need to get it back together pronto and don't have one, it's a consideration.

If it's cracked, chunks missing, dented severely, or out of round, then I'd probably not. CopperNick makes a good point about smearing some goop on it to help seal the used one if it looks decent, more of a precaution.
 
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Clone TIE Pilot

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Here is a online picture of the O2 sensor location on TES headers. Its pretty close to the flange.

159395d1231051087-edelbrock-tes-headers-y-pipe-f-s-headers-2.jpg


When I replaced the head to header gaskets I had to loosen the exhaust pipe flanges so I could move the headers out of the way. Guess I will need to unbolt the Y pipe and doublecheck the doughnuts.
 

Clone TIE Pilot

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Got the Y pipe off today and what a mess it was. The two passenger side bolts came out easy but the driver side were frozen bad. One bolt broke but I was able to grab it with a vise grip and torched it off. The driver side had some soot marks indicating a leak but the metal doughnut seal looks fine. The passenger side seal is toast though, for some reason the doughnut on that side is a fiber seal instead of metal.
 

SS_Malibu

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Sep 27, 2021
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Mesa, AZ
I personal would put new on both sides just to help eliminate that being a possible issue especially since you have the "Y" pipe off and those doughnuts are cheap enough.
 

CopperNick

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Feb 20, 2018
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A "while I'm there" to do thing at this point might be to take a wire wheel or a Red scuffing pad and give the gasket surfaces a good cleaning. That would get you clean surfaces for the gasket and/or sealant to mate up to and disclose any nicks or cracks in the flanges that might allow exhaust to sneak past.

As a personal aside here, I am not too impressed with where that mfgr put the bung for the O-2 sensor. Being shorties as they are, I appreciate that the amount of available real estate for that purpose is limited but, and typically, as part of the post requirement installation instructions, most O-2 sensors usually get put somewhere in the downstream exhaust tube that is flat and straight. No engineer me, but the supposed thinking is that in the straight section the velocity of the gases is fairly constant and that helps the sensor to get a clean reading to ship back to the CPU.



Nick
 

Clone TIE Pilot

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Thread starter
Aug 14, 2011
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Galaxy far far away
A "while I'm there" to do thing at this point might be to take a wire wheel or a Red scuffing pad and give the gasket surfaces a good cleaning. That would get you clean surfaces for the gasket and/or sealant to mate up to and disclose any nicks or cracks in the flanges that might allow exhaust to sneak past.

As a personal aside here, I am not too impressed with where that mfgr put the bung for the O-2 sensor. Being shorties as they are, I appreciate that the amount of available real estate for that purpose is limited but, and typically, as part of the post requirement installation instructions, most O-2 sensors usually get put somewhere in the downstream exhaust tube that is flat and straight. No engineer me, but the supposed thinking is that in the straight section the velocity of the gases is fairly constant and that helps the sensor to get a clean reading to ship back to the CPU.



Nick

They were made by Edelbrock many years ago. The TES are not the best headers but they are designed to bolt directly to factory hardware and be 50 state legal. These headers are still a big improvement over stock exhaust manifolds, through Hooker's version of smog legal headers, the 2050s were better than these Edelbrock TES headers. I do use a heated O2 sensor with these headers.
 
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