Cracked 31 exhaust manifold

[Guest arbys]

This past weekend I took my 31 model 60 out and developed a crack in the exhaust manifold. By the time I arrived home I noticed the crack went completely around. My first thought is to have it welded. Has anyone had success with that? If not I'm looking for another manfold. What other years could I use( 32,33,34) ?

[Larry Schramm]

Cast iron can be welded by a competent welder. I have a guy that welded the water pump on my truck and it does not leak at all and that was a couple of years ago. If you need help, let me know since you are in Mich also.

[Bob Engle]

Long term, you will have little success with a welded exhaust manifold on these early straight 8's. There is a lot of expansion and contraction from heating and cooling. The early cast iron is not of a very good quality with a lot of sand and other impuities in the castings. I have one 50 series manifold that was welded, but it again cracked about an inch away from the first crack.

32 and 33 manifolds will work on your engine. They are hard to find due to the cracking problems.

Be sure to follow the instalation procedures faithfully on instalation of the manifold. The manifold must be able to slide on the gasket at the head attachment. Liberal use of graphite or moly antisieze on the gaskets is necessary. The Manifold mounting studs have a domed heavy washer That is supposed to allow the manifold is move. Don't over tighten the manifold studs!!! I polish the washer contact points so the washer can move on the surface.

Under exhaust heat, the manifold will expand. Cast iron can take high compression forces under heat expansion without problems. Upon cooling, if the manifold can't easily slide on the surfaces, it will put the manifold under tension forces and cast iron is terrible for tension strength.

Due to the inherent cracking problem on these manifolds, Buick eventually switched to 3 pieces exhaust manifolds.

I recommend that on old engines with rusted manifolds, that they be removed the gaskets properly lubed, all rust on the washers and locking surfaces be polished and the nuts be carefully lightly tighened upon instalation.

Bob

[trp3141592]

Hi Arby's,

I have had three occasions to have cast iron welded. None worked out. The castings broke nearby or at the weld. Dealing with the manifold is enough work that you likely don't want to do it multiple times, so I suggest trying to find a replacement manifold and doing it once. See Bob Engle's comments above for installation info.

BTW, I am in Niles, so we're likely neighbors. Where are you located?

--Tom

[Mark Shaw]

All good comments, but another PWD member recently had a very hard time finding a replacement.

My 1931 model 57 manifold was welded long before I got the car and has performed well for many years. As Larry Schramm indicated, you must find a competent welder that has an industrial oven to preperly pre-heat, weld, and anneal the part after welding to remove the stresses around the heat effected zone of the weld.

[budd28]

you can your manifold welded just make sure you preheat manifold first.I cracked mine on a 1951 special took the manifold off made a jig with manifold studs on a piece of flat channel iron [so it wouldn't move] veed out the crack welded the manifold back together.Been holding ever since 2000

[Guest Earl]

This guy really does nice work. It's expensive, but he repaired an old hard coal stove I had and did a great job of it. He mostly works on antique car exhaust manifolds though and should be able to tell you right away what can be done with your manifold. He really likes working on the pre WWI Buick engines. It's quite a process he goes through to get the repair done, but he hardly ever gets anything back. I certainly couldn't see a thing wrong with the way he did that old Round Oak Baseburner. It had about 10 broken castings and I heated my house with it for a couple of winters and nothing cracked open on it again. And I think those old coal stoves have a lot of expansion a contraction issues as well. Anyway, he's a great guy to visit with ( I can't recall his name just now). And you can send him a picture of what you are up against, he should know from that. Good luck now.

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