Header leak help!!!

[1981silverz28]

I have a set of Flowtech afterburners on my 81 Z28 w/350.I cant get the left side to stop leaking.I've had the flange surface smoothed by a machine shop ,used paper gaskets,copper ones,copper ones with red hi-temp silicone on them ,and tonigt I put on percy racing aluminum ones and the d%&@ things still leak.What can I do next ?? I am about to lose my marbles over this!!Oh yeah the headers fit the engine compartment great so I don't want to replace them if I don't have to.

[David Pozzi]

Any chance the bolts are coming loose?
Use long header bolts, the extra length gives more grab, helps keep them from coming loose. I like to use antiseeze on the bolts, the stuff dries out and actually helps hold the bolts, especially on aluminum heads.

Is it allways leaking in the same spot?

[streetk14]

I had a set of those percy's gaskets for a long time, and they never did seal right. I have had very good luck with Fel-Pro header gaskets in the past. I recently installed a set of Fel-Pro's along with a set of split-lock header bolts. Those headers aren't coming loose, and that annoying ticking is gone!
Are you sure the leak is coming from the header flange, and not the collecter gasket? Are you tightening the bolts evenly, from the inside-out?
-Andy

[paul67]

How thick is the hedder flange as i found they need to be min of 3/8" thick as the thinner one's tend to bow
paul67

[1981silverz28]

It leaks between the two in the middle or the one in the back ,and its from the flange not collector .I have a set of allen head header bolts (not long enough?) and the flange is 3/8".I cut the flange between the cylinders to help with the warping.I retighten the bolts after about the first 60-70 miles( 1st drive to and from work )then again after about a week and they still leak.Do I need to have them trued by the machine shop again and start over? what brand of split-lock bolts did you use? Thanks

[paul67]

do you see a soot mark where the leak is, try using exhaust gasket paste with the gasket.
paul67

[1981silverz28]

I've put red Permatex Hi-heat on it, is that what you're talking about or is there something better?

[streetk14]

I used Breslin performance stainless steel header bolts. They are availiable through Summit. Although, it doesn't sound like loose bolts are not your problem. Hate to say it, but a new set of headers might be the best answer.
-Andy

[ROAD WARRIOR]

I've put red Permatex Hi-heat on it, is that what you're talking about or is there something better?

I dunno, broh...if you can't even get a seal using Permatex and new gaskets, something ain't right! I've been able to seal up 2 dolla swap meet heddas that had flanges wavier than the Atlantic Ocean by using Permatex as my "secret weapon!" As a "forth and goal" trick, this is what I do: get 2 sets of Fel-Pro exhaust gaskets. Not the header gaskets, the regular parts house/ OEM replacement style gaskets that have a "foil" side with dimples. Make a sammich' outa them, with Permatex holdin' them together. Let the P-Tex dry. Then, put a coating of P-Tex on each side of them, and install 'em. It can be a 'lil messy, so take yer time. Then tighten the headers up, and let them set while the P-Tex dries. Fire up, heat cycle, and retighten.

Good luck!

[zbugger]

Ok, here's what I did, and I hadn't had ANY problems with leaks. I use Earl's Pressure Master header seals. Not gaskets. They are a soft aluminum in an aluminum frame. I used the same little header bolts that came with my hedman hedders. I tightened the bolts when I installed the seals, and then I checked them about a week later. No leaks, and only one bolt kinda came a little loose. I re-tightened it, and then checked it again about a month later. Still tight. I didn't touch them for two years when I pulled the engine. Earl's Pressure Master Seals work awesome. I always recommend them.

[68protouring454]

not sure if you are doing it or not, but i have used 2 sets of cheap header gaskets and high temp silicon to seal cheap headers, however it is KEY to let the silicon sit overnight before starting engine, are you doing this??
jake

[CAMAROBOY69]

THIS is how to fix any gasket leask on ANYTHING including headers.
3M SUPER SILICONE SEALANT. I have been using it for years and never have never had a header leak since. This stuff comes in a blue tube with white lettering. Some local parts stores carry it. You wont need any gasket if you use this stuff. Can be applied directly to headers and will not melt off. It is only about $7.00 a tube. I put it directly on my block then bolt my headers on with no gasket. Works perfect and its clear.

[1981silverz28]

Thanks guys ,I think I'll get some 3M in the blue box and try that this weekend.I'll let ya'll know how it goes.Again thanks for all your help!!