Exhaust Manifold Repair Ideas

[Joe C.]

Re: Exhaust Manifold Repair Ideas

Thanks to all who gave suggestions on the exhaust manifold repair. I just picked it up at the machine shop today. The did the spray weld technique and retapped the hole. They also shot blasted it and cleaned it up real well.

The weld is not quite as perfect as I would like but it is a vast improvement. You can tell it's been repaired. I'll take a picture and post it after it's installed.

A couple of questions for you all:

• Now that it's clean, should I "dress" it in some fashion or just leave it as is? I do drive the car regularly but some day intend to do a proper, body-off restoration.
• How should I clean the mating surface on the head? It is still installed on the engine in the car. Any good ideas on how to plug the exhaust openings in the head while still being able to clean the mating surface for the manifold?

Thanks,

Michael,

If you can bring it back, and have them add excess material, then you can shape it to its old form, and then "simulate" the original rough cast appearance. As was said previously, it can be made to be indiscernable.
There are various manifold "dressings", and Calyx comes to mind. Some people report success with ordinary hi-temp spray paint, which "seasons" as the manifolds are heated.

Jerry MacNeish will add a white ceramic coating, which must be painted with "cast blast" before mounting. This will keep them looking new "forever".

http://www.z28camaro.com/

Did the machine shop surface the flanges on the manifolds? The same should be done to the heads. You can do a decent job with a mill bastard file. stuff the ports with rags, then blow them out with compressed air before removing them.

Joe

[Michael A.]

Re: Exhaust Manifold Repair Ideas

Michael,

If you can bring it back, and have them add excess material, then you can shape it to its old form, and then "simulate" the original rough cast appearance. As was said previously, it can be made to be indiscernable.
There are various manifold "dressings", and Calyx comes to mind. Some people report success with ordinary hi-temp spray paint, which "seasons" as the manifolds are heated.

Jerry MacNeish will add a white ceramic coating, which must be painted with "cast blast" before mounting. This will keep them looking new "forever".

http://www.z28camaro.com/

Did the machine shop surface the flanges on the manifolds? The same should be done to the heads. You can do a decent job with a mill bastard file. stuff the ports with rags, then blow them out with compressed air before removing them.

Joe

Joe,
The machine shop did surface the manifold and I've been trying to figure out how to clean up the mating surface on the head.

I assume the rags and file process you are suggestion is a hand process with the head still on the engine. Is there a technique or trick you would suggest?

Thanks
Mike

[Joe C.]

Re: Exhaust Manifold Repair Ideas

Joe,
The machine shop did surface the manifold and I've been trying to figure out how to clean up the mating surface on the head.

I assume the rags and file process you are suggestion is a hand process with the head still on the engine. Is there a technique or trick you would suggest?

Thanks
Mike

Yes, with the heads installed. They should not be "bad" at all, really. Most of the strain takes place on the manifolds. As long as all 3 mating surfaces are flat, independently, then the manifold bolts will pull them into alignment. We're only talking a few thou here. Unless the surfaces are grossly damaged, all you need to clean them up is some emery cloth and your fingers. (Standard Abrasives sells a "gasket remover" attachment for a die grinder. Kindof like a "flapper" tool. Overkill.....like how a lot of women use4 or 5 different "loofah" sponges to clean various parts of their anatomy.) Any small gaps will eventually "carbon-up" and seal.

Stuff a rag in there tight, then either vac or blow out grit with air. Remove the rag with a (needle nose) pliers. Anything you missed will come out with the rag.



Joe

[Michael A.]

Re: Exhaust Manifold Repair Ideas

Joe,
Thanks for the advice. The emery cloth worked perfect. I'm getting ready to install the manifold, probably tomorrow.

One stupid question.... I'm putting gaskets in. Do I put the metalic side of the gasket facing towards the head or towards the manifold? My guess is the head, that's the hotter side, but I wasn't sure.

Cheers
Mike

[Patrick H.]

Re: Exhaust Manifold Repair Ideas

Joe,
Thanks for the advice. The emery cloth worked perfect. I'm getting ready to install the manifold, probably tomorrow.

One stupid question.... I'm putting gaskets in. Do I put the metalic side of the gasket facing towards the head or towards the manifold? My guess is the head, that's the hotter side, but I wasn't sure.

Cheers
Mike

Mike,

I would NOT use gaskets, ever again.

I tried them 3 times. I ended up replacing them yearly because they always burned out. Finally I had the manifolds resurfaced and reinstalled them with no gaskets - ZERO problems since then. If your manifolds were resurfaced on the head side (you stated they were) you do NOT want to install gaskets.

Well, not unless you like replacing them all the time.

Patrick

[Michael A.]

Re: Exhaust Manifold Repair Ideas

Patrick,
The manifold was surfaced and I've cleaned the head with emory cloth as suggested by Joe. I was tempted to try it without gaskets but wasn't sure. If I go without gaskets, will I have some leaks to start until it seals up with carbon? I'd hate to install it without gaskets and see leaks right away but I could accept that if it would likely seal up soon. What have you found.

Thanks,

[Patrick H.]

Re: Exhaust Manifold Repair Ideas

Patrick,
The manifold was surfaced and I've cleaned the head with emory cloth as suggested by Joe. I was tempted to try it without gaskets but wasn't sure. If I go without gaskets, will I have some leaks to start until it seals up with carbon? I'd hate to install it without gaskets and see leaks right away but I could accept that if it would likely seal up soon. What have you found.

Thanks,

You won't have any leaks at all. It will be fine.
GM built millions of engines with heads and exhaust manifolds not as nice as what you just prepared and had no issues.

Patrick

[Joe C.]

Re: Exhaust Manifold Repair Ideas

Patrick,
The manifold was surfaced and I've cleaned the head with emory cloth as suggested by Joe. I was tempted to try it without gaskets but wasn't sure. If I go without gaskets, will I have some leaks to start until it seals up with carbon? I'd hate to install it without gaskets and see leaks right away but I could accept that if it would likely seal up soon. What have you found.

Thanks,

No gaskets. In the unlikely event that there are any small leaks, you'll never even know that they were there. They'll seal in short order, anyway.

GM never used them. Unless your manifolds were badly strained (warped) then it's not even necessary to surface them! Consider what you've already done "above and beyond" what is done by most.


Joe

[Jim T.]

Re: Exhaust Manifold Repair Ideas

When I replaced my 70's engine with a ZZ crate engine I used my original exhaust manifolds on the aluminum heads. I had exhaust leaks between the exhaust manifolds and heads. I removed the exhaust manifolds and installed the exhaust manifold gaskets that were used on the 1986 and later Corvette aluminum head L98's. Installed them over 14 years ago and they are holding up just fine not requiring any replacement.