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Old 11-02-2019, 12:11 AM   #1
Need BB
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Default OEM Uppipe Leaking

I recently had to replace my EWG setup with an OEM STI uppipe to pass SMOG in California. I went with grimmspeed gaskets, but my uppipe is still leaking at the uppipe-headers flange. It seems the OEM uppipe flange is slightly warped as the gasket is tight by the bolts, but not the gasket in not as compressed in the center.

Has anyone ever had this issue with the OEM uppipe? I went with OEM as I didn't want to deal with leaks

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Old 11-02-2019, 06:44 AM   #2
NickVu
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I had something similar with the downpipe split cat section. The flange bent over time and didn't seal. The nuts were so corroded they were already rounded off. I had to drill off the entire stud. Grind the flange flat again with a belt sander. Then use bolts and nuts to fasten it.
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Old 11-02-2019, 01:46 PM   #3
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If I can't easily fix it it seems best to just get an aftermarket uppipe. Thanks for the input.
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Old 11-04-2019, 10:29 AM   #4
raisingAnarchy
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How are you guys identifying the leaks? I've been having trouble tracing an exhaust leak somewhere along the manifold/uppipe. Soapy water just boils immediately, even 1 minute after a total cold start...
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Old 11-04-2019, 02:25 PM   #5
StarkWRX
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I saw some red gunk in the flange groove at the down pipe / mid pipe junction and I’m guessing it is high temp silicone sealant.

Maybe you can try some for your issue but that flange is much hotter than the down pipe.

I remember I used some grey exhaust sealant for my motorcycle once.
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Old 11-04-2019, 02:31 PM   #6
NickVu
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If it sounds like whistling, major flange area leak. Otherwise you'll have to take everything apart and look for soot.

If the flanges look okay, it's a flex joint somewhere.
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Old 11-05-2019, 01:47 PM   #7
KGilstrap
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Try sealing it up with some copper seal. Works better than exhaust gaskets
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