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Welding Exhaust Manifolds?

Esteban86K5

Esteban86K5

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I have a crack on my passeger side manifold in the Burb. Sounds horrible when driving down the street. I was wondering if anyone has had any luck with welding up the cast manifolds? I know cast is more difficult to weld but I have never done it. I am planning on a new exhaust for the Burb from headers to tailpipe, but not right now and I don't want to spend money on a new manifold just to take it off when it all gets replaced. So any insight or help with this would be appreciated /forums/images/graemlins/dunno.gif
 
the manifiold are cast iron so im pretty sure you cant weld them but sombody may correct me if im wrong /forums/images/graemlins/waytogo.gif
 
You will need an extra cylinder head to do it, grind out the crack acout a 1/16 of an inch, the full length of said crack, bolt to cylinderhead and then(here is the secret) heat the manifold with a torch, (need another person to help)get it good and hot, just below cherry red, it takes a while to heat the whole thing so be patient, then while it is still just below cherry red, weld with wire feed or mig. make sure to keep manifold hot with torch, when crack is filled, stop and let it cool, NO WATER, DO NOT TEMPER,when totally cool, you can remove from head and use.I know, pain in the a$$, huh!?! /forums/images/graemlins/weld.gif /forums/images/graemlins/weld.gif /forums/images/graemlins/weld.gif /forums/images/graemlins/weld.gif /forums/images/graemlins/weld.gif /forums/images/graemlins/weld.gif
 
It's better than buying a new one or listening to this damn tick!!

Thanks /forums/images/graemlins/thumb.gif
 
i wouldent tink a used one from a junk yard would cost to much /forums/images/graemlins/dunno.gifmight be less hassel
 
I done this to dads on the pickup. Small drill bit I drilled just past the end of the crack at both ends, heated it with the torch and welded the crap out of it. First I welded the crack letting it burn in really good, then I layed about a 1" wide weld over the top.

As mentioned above its changes the size of the manifold when you heat it up. We had to clear out about a 1/16" out of the front hole to get it back on. So if you do have an extra head bolt it up and weld away! /forums/images/graemlins/waytogo.gif /forums/images/graemlins/weld.gif
 
Also, if you have a gas welder where you are, buy some rods made for welding cast iron, then heat it up and weld /forums/images/graemlins/waytogo.gif
 
They make rods that are no pre-heating required to stick weld cast iron. I wouldn't use them on a structural piece but on an exhaust manifold I bet they'd work well.
 
I've had limited success welding them ,usin nickel rod--I have also brazed them with a torch and brazing rod--I think the braze job lasted longer.I have the luxury of having several large junkyards three miles away,with plenty of trucks to pick on,and fair prices--they also now carry a line of brand new exhaust manifolds for about 50 bucks and up--so far none over 100 bucks that I've bought,even the rare "ram horns" are being reproduced now.I recently bought a set of 460 ford ones there (brand new)for 60 bucks each.Your local salvage yard may offer the same deal too,I'd make some calls--it might be cheaper to get a new one!.
 
i wouldnt spend money buying another manifold if your planning on buying headers.

i had the same thing happen to my blazer, cracked pass. side manifold and was planning on new headers in the future.accually mine wasnt cracked, it was completly split between cylinders 2 and 4.

what i did was use the cheap muffler repair junk from pep boys. first get the paste stuff and fill the crack. let it dry for a day before go to the second step.

next get the tape. make sure you get the kind that is self adhesive and not the white kind that needs water. it should look like snake skin once you pull off the backing. cut little strips out and wrap it around the crack.

there should be metal wire in the package , wrap that around the repair to keep it inplace while you heat it up. run the truck for 10 minutes or so and the tape bonds to itself and turns rock hard.

i used this method and it held for over two months while i ordered exhaust parts. cost about 6 bucks, completly silenced the leak. method was recommeded by a buddy and worked alot better than i expected.
 
They also sell some stuff called "Pyro Putty" that seems to work pretty good too--but all the epoxy type repairs wont be permanent--but my welded and brazed ones didnt last that long either,they were so thin the cracks just kept spreading. /forums/images/graemlins/frown.gif
 
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