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July 27, 2009 3:22 p.m. ClemSparks SuperDork

Hey all,

So, I found a cheap set of used headers for my thirdgen f-body and put them on and a new catback system. The problem is that I can't get the header-to-y-pipe junction to stay sealed on these.

It seems these are setup to take a "doughnut" gasket like a standard cast manifold would use. But it has standard 3-bolt, 3-inch collector flanges.

What has happened is that the flanges have warped. You can see it here:

In the next photo the lower of the two flanges is straighter (because I replaced it...it's the only one that will come off without cutting a pipe). You can see one straight one and one warped one here. This side seems to be sealed up acceptably:

As far as I can tell, my only real option at this point is to actually CUT the collector, put a new flange on, and weld the collector back together. This is not an easy/fun option...but it's a heckuva lot cheaper than new headers for a car I'm pretty sure I won't keep too long (and isn't worthy of new, coated headers).

I figure trying to hammer them flat won't work because they're already annealed from who-knows-how-many heat cycles in the past.

I'm posting here in case anyone has some thoughts on how to rectify this problem with what I've got. Just a "two heads are better than one" scenario. I'm stuck "in the box" on this one. Help me think outside it.

The flanges float freely on the collector and y-pipe when not bolted on. The driver side portion of the y-pipe is a slip on, so it can be replaced (and has been) without cutting/welding. The other three, I'm not so lucky.

Clem
July 27, 2009 3:27 p.m. ManofFewWords Reader

At the risk of sounding like a hack, you could weld it.
July 27, 2009 3:36 p.m. The Brown Stig SuperDork

Take the header off and see if you can straighten that flange. Even if you weld a thicker solid flange you should be fine.

Look for a "dead soft" aluminum gasket for the flange (Summit / Mr.Gasket).

Reassemble and have fun.
July 27, 2009 3:47 p.m. ClemSparks SuperDork

The Brown Stig wrote:

Take the header off and see if you can straighten that flange. Even if you weld a thicker solid flange you should be fine.

Look for a "dead soft" aluminum gasket for the flange (Summit / Mr.Gasket).

Reassemble and have fun.

I'd thought, breifly, about hammering them flat and welding on a "spreader" or "doubler" or such. But after that trouble, it might be about the same to cut off the collector and put on a new flange and reweld the collector...I don't know.

Are you saying forego the donut gasket, get the flange straight, and use a flat, typical, 3 bolt flange gasket? I hadn't thought of that...

Clem
July 27, 2009 4:47 p.m. Jensenman SuperDork

The flanges are too thin which makes them warp and soft gaskets are only a temporary fix. If you can find them, there are donut gaskets which have a steel insert that slides into one of the pipes that should help seal it.

Rather than cut the collector, I'd cut some new flanges out of thicker stuff (say, 3/8"), split the old flanges and take them off, split the new flanges, assemble and weld back together. You could also flatten the bent flanges, then weld a piece of 1/8" x 3/4" vertically along the sides of the flanges thus making them more rigid.

Or, if you have room, cut the collector flange off of the header and use a stepped exhaust reducer and a set of T bolt clamps.
July 27, 2009 8:47 p.m. ClemSparks SuperDork

Jensenman wrote: split the new flanges, assemble and weld back together. You could also flatten the bent flanges, then weld a piece of 1/8" x 3/4" vertically along the sides of the flanges thus making them more rigid.

This is EXACTLY why I posted here...I think this could be a good solution that I had not been able to come up with...

Heck, I've gotta weld one way or another, might as weld the part I actually want to put on.

Thanks and keep 'em coming just in case ;)

Clem
July 28, 2009 6:13 a.m. 44Dwarf Reader

Don't weld weld'em you just need the right gaskets and some "beam clamps".

Jeg's and summit both sell some nice thick copper wraped gaskets theres a fibber layer in the middle so they do crush down but still there thicker then the all fober units.

Beam clamps are small cast iron c clamps used to hang stuff from steel i beams.

If you realy don't care about the headers or the folded over flang cracks then sawz-all off the fold on the header and adapter then use a OD to OD muffler adapter.
Hint if you think you'll be keeping the vehicle long enought you might need to drop the exhaust coat the header with red silicone seal before sliding on the OD adapter and don't clamp it let it sit over night to dry up. In a short time it will rust up to a tight fit but will come off easyer later you just cut a slice down it with the muffler cuter and peal it off.

My old bronco had some nice high $$ headers and the flange cracked after i lost the hanger.

44
July 28, 2009 7:16 a.m. walterj Dork

place C clamp on bent area, tighten until it seals and spot weld it at the center. Use enough weld to hold it but little enough you can separate the pipes with a cutoff wheel later.
July 30, 2009 2:53 p.m. ClemSparks SuperDork

I think the cause of my problem may have been my assumption that these headers take a doughnut-type exhaust gasket/seal.

I'm betting I was mistaken there and these just take a plain, old, flat, paper, 3 bolt, 3-inch collector gasket.

So...if I pound them back flat (or even a go a little in the other direction), I might have half a chance of getting these things to seal.

Hmmm....

Clem
July 30, 2009 4:59 p.m. JmfnB SuperDork

Check Jegs and summit. Your repairs will be easier.
July 31, 2009 4:56 a.m. foxtrapper SuperDork

How redneck a repair do you want?

Option 1 Permatex ultra-copper works real well on header flanges. You goo a thick bead on the faces, let it set for about 10 minutes, and then bolt it all back together. It'll likely hold for several months.

Option 2 Go down to you generic auto store and peruse the exhaust gaskets. They tend to have the donut gaskets sitting in a box. Find a big that fits and use it.

Combination of 1 and 2 That's what I'd likely do if it were mine. Well, I'd probably try option 1 first, but if it failed while I still owned the car, I'd go on to the combination aproach. Slathering ultra-copper all over some seal I found in a bin and stuffing it in the joint.
July 31, 2009 6:25 a.m. JmfnB SuperDork

Three words:

Band Clamps!