Replaced header to midpipe gasket ring is leaking, is it normal?

[vlkvlk]

So I was doing exhaust smoke machine test to diagnose bank 2 misfire on all cylinders. Apart from leaking SAP system (https://www.m3post.com/forums/showthread.php?t=1890730).
Head-to-midpipe gasket was leaking. So I replaced both gaskets, but it's still leaking right after install!

Is it normal to have small leak there?
Is there any special trick to replace these?
These are HJS gaskets that look like OEM, should I have splurged for OEM instead?

[roastbeef]

Yes. They get worn and can leak after a few fittings.

[Redd]

No it's not normal to leak after you install new gaskets. They may be slightly undersized. I would get OE. They aren't expensive.

[vlkvlk]

I wonder if SAP leak or this caused misfire...

Originally Posted by Redd

They aren't expensive.

But it does add up - you need to replace a lot of stuff on these cars overtime!

I don't understand why there are no cheaper copper bolts/nuts, only OEM is available, and they are expensive. I'm reusing original nuts and bolts, but honestly, I don't think they are the problem.

[vlkvlk]

Actually, stupid question. Should flange be welded to header or not?

Flange on bank 2 header is moving freely, flange on bank 1 header doesn't move, and it looks like there is a weld line around it. (My assumption is that weld is unrelated, and flange just got stuck on it overtime).

[tbuck]

Yes, one side is fixed, the other is not.

[LatifE90]

I've had this happen to me a few times, overtime these donut gaskets cause the misfire bank 1 & 2. I usually change mine every 20k miles with oem. Pricey but it keeps the car running smooth

[tdott]

Another reason to get a set of headers! This connection is eliminated.

Usually new gaskets fix it, but I haven't done a smoke test to verify.

Did you clean the area up when removing the old ones? Sometimes they can come a part and would probably cause a bad seal if pieces are left in there.

[vlkvlk]

Originally Posted by tdott

Another reason to get a set of headers! This connection is eliminated.

Usually new gaskets fix it, but I haven't done a smoke test to verify.

Did you clean the area up when removing the old ones? Sometimes they can come a part and would probably cause a bad seal if pieces are left in there.

I would get new headers only if header gasket is leaking 😂otherwise dropping subframe is more than I want to do at the moment. Missing another track day because of all repairs!

It looked quite clean, I used 99% alcohol to clean of penetrating oil I used on bolts. Bank 2 header has some slight scratches in one area - looks like connection got loose and midpipe was rubbing on it a bit (had to replace engine mounts a bit ago, my guess extra vibrations from bad engine mounts damaged the gaskets, leading to leak)