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Idea for an exhaust manifold fix
https://www.slantsix.org/forum/viewtopic.php?t=18757		 Page 1 of 2
Author:  Jeb [ Sun Jul 23, 2006 6:30 pm ]
Post subject:  Idea for an exhaust manifold fix
The exhaust manifold to pipe gasket on my Duster keeps on burning and blowing out becasue something is warped (not sure which flange it is though) and it won't seal properly. But tonight I had a brainstorm. When I swapped my manifolds I used the gooped metal gasket (RTV/metal gasket/RTV) between the manifolds as was recommended by Dan on this site. Well the surfaces on the heat crossover were pitted badly on both manifolds but this sealed them perfectly. I was wondering, could I do the same thing with the manifold pipe gasket? Put RTV on both sides, allow to "skin" over, and then install just as I did with inter-manifold gasket. I don't see no reason why this wouldn't work, as it worked beautifully with the intermanifold gasket and it doesn't leak!

So, what do you guys think?
Author:  VDART [ Sun Jul 23, 2006 6:41 pm ]
Post subject:  exhaust gasket
yes-- you could do this-- i just did the same thing -- went to exhaust shop-- purchased some exaust cement & sealed up a leak that had been there for some -time -- the ratchet at the shop really liked the stuff!!

It's been on for 1 week- & has held up great!!! Cheaper than gaskets--- tube cost like less than $4.00 [/i]
Author:  SlantSixDan [ Sun Jul 23, 2006 7:44 pm ]
Post subject: 
I never had much success using that technique in that location. If those surfaces are warped, they aren't gonna seal, and gaskets will blow out regularly.

The problem at the intake/exhaust manifold junction is different; usually those surfaces aren't warped, but the stamped-steel gasket design sucks (blows, actually).
Author:  Jeb [ Sun Jul 23, 2006 8:56 pm ]
Post subject: 
Exhaust cement is some pretty tough stuff though, a lot tougher than RTV.
I'll give that a shot. It will be sort of like a soft header gasket

Dan, which surface is it that usually warps, the manifold or the headpipe flange? If these things had a donut seal they would not have this problem.
Author:  SlantSixDan [ Sun Jul 23, 2006 9:08 pm ]
Post subject: 
Quote:
Exhaust cement is some pretty tough stuff though, a lot tougher than RTV.
I'll give that a shot. It will be sort of like a soft header gasket
...for about three of Vdart's weeks, then it'll be completely cured, will be rock hard, will crack, and will fall out. Been there and done that!
Quote:
Dan, which surface is it that usually warps, the manifold or the headpipe flange?
Headpipe flange.
Quote:
If these things had a donut seal they would not have this problem.
Quite true.
Author:  Jeb [ Sun Jul 23, 2006 9:15 pm ]
Post subject: 
So is there any fix besides having to get another flange welded on?

Do you know of a better gasket material?
Author:  SlantSixDan [ Sun Jul 23, 2006 9:21 pm ]
Post subject: 
My experience is that once the flange warps, the only effective and lasting fix is a new flat flange. I tried a bunch of ways to get the warped flange on my '65 to seal...and never succeeded for more than a couple weeks at a time. Once you have a flat flange, any decent-quality stock-type gasket will work fine.
Author:  Jeb [ Sun Jul 23, 2006 9:39 pm ]
Post subject: 
Hey Dan look at this. Looks promising. Do you think it will fit or are the holes too far apart? My headpipe flange is a 2 1/4 also.
Author:  tophat [ Mon Jul 24, 2006 4:31 am ]
Post subject: 
Can you get the pipe out of the car easy? If so, just take a file or belt sander to the flange to "mill" it flat again. I suppose you could file it in the car but that would be a pain in the a$$. I spent many years working in exhaust shops, and I agree with Dan, sealer is a temp fix here at best. With the sealer you get the fun of getting all the rock hard sealer back off once it fails.

BTW, you could have a custom pipe made to take a GM style "half donut" gasket, but it would be much easier to just flatten your flange.

good luck

tophat
Author:  vynn3 [ Mon Jul 24, 2006 5:34 am ]
Post subject: 
A few years ago (before my Dutra Duals), I had the same problem. I took it to a trusted muffler shop. The guy cut the flange off, put it in a vise, and beat the crap out of it with a BFH. Welded it back on, bolted it up, ad it's never leaked (from there) since. What was encouraging is that it seemed as though he'd done that a few times before, and was confident that it was a permanent solution.

So far, so good...

VM
Author:  Jeb [ Mon Jul 24, 2006 5:50 am ]
Post subject: 
I have found a copper gasket. It is in a link a little further up. I think this might fix it. It is thick and has a metal sealing ring in it.
Author:  DusterIdiot [ Mon Jul 24, 2006 7:39 am ]
Post subject:  THe quick fix...
One member about 4 years back offered a list of alternative gaskets from other vehicles that work. I don't remember where the list went. The Ford Econoline Van like 1980's with the 302/351 has a flange similar to our pipe and the gasket is about 3/16" thick with a metal ring. I used one on a troublesome pipe swap a while back and it worked great and didn't leak, I also have had a set of these on the Hpak duster without any trouble for 3 years now.

Jeb is your cross bracket still hooked up? The '74 had two anchor points for the exhaust the "flex" connection in the rear, and a metal "strap" type bracket that bolted to the bellhousing, if that one isn't in good shape the pipe will swing when you hit some nice bumps.


-D.Idiot
Author:  SlantSixDan [ Mon Jul 24, 2006 9:14 am ]
Post subject: 
OK, let me try again...one more time:

Until you fix the warped flange, this junction WILL NOT SEAL. You are wasting time and effort by shopping for magical gaskets and gookums that will seal a warped flange. There is no such a thing. Once you have a flat flange, that copper gasket looks dandy. Until you have a flat flange, you are pissing into the wind.

Please don't ask "What about this gasket/gunk/sealer/sticky stuff/other half-baked measure, will this make it seal?" again. You know the answer. Now quit futzing around and go fix it right!

Image
Author:  stickylifter [ Mon Jul 24, 2006 9:17 am ]
Post subject: 
Could you take a die grinder to the exhaust manifold and bevel it so that you could use a donut style head pipe? I'm getting ready to make my exhaust so I'm watching this discussion with great interest.

I bought a doughnut type flange and head pipe from the auto store and was going to weld it on and cut off the doughnut flange.
Author:  SlantSixDan [ Mon Jul 24, 2006 9:21 am ]
Post subject: 
Quote:
Could you take a die grinder to the exhaust manifold and bevel it so that you could use a donut style head pipe?
To make it leak-free and squeak-free would take a level of precision grinding not available with a handheld die grinder or other tool.
Quote:
I'm getting ready to make my exhaust so I'm watching this discussion with great interest. I bought a doughnut type flange and head pipe from the auto store and was going to weld it on and cut off the doughnut flange.
Waste of time, money and effort. You're going to have a new headpipe, right? So, you're going to have a new flange, right? That's all you need for decades worth of good service from this junction.
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