Update on 5000 manifold....

Ron-MO · Jun 6, 2011

I debated over the weekend on whether to try to weld, braze or just order a new manifold, and finally decided "what have I got to lose" by giving brazing a try. I had sucessfully brazed an exhaust manifold from a small block chevy many years ago, but knew it took a lot of heat, and was not friendly at all. Here is end result, and I believe it will outlast me, and cost is low so far (free pipe from the scrap pile). I will have to pick up a coupling and pipe nipple tommorow to make it long enough to get muffler through the hood, but should still keep it under $10 cost to repair vs. nearly $100 ($61 from this site with $30 shipping). I believe it will survive all but the most severe hit from a tree limb, and the muffler will proably let go first. Secret to sucessful brazing is to get it super clean and just right amount of heat (used a cutting torch tip and took my time)

john_Bud · Jun 6, 2011

Nice result and it looks a lot better than the mess you were given. The cost to you was sure right!

Ron-MO · Jun 7, 2011

Considering the old mess was pretty much just sitting on the manifold, it is drastically improved. 1.5 inch pipe gives the perfect size for the existing Donaldson muffler to fit. I did cut off about 2 inches of the manifold to get a fairly good edge to braze to, then wire brushed around the area I was going to braze and just inside where the pipe goes through. The pipe actually extends inside the manifold about 3 inches or so. It could be strengthened by drilling a hole or two through the manifold about 2.5 inches down, then brazing through and filling the hole to secure the pipe into the manifold further, but I do not feel it is necessary. I could not come up with a pipe that was long enough so I will have to extend with a coupling and probably a 4 inch nipple, then cut off the end threads where muffler clamps on.

Ultradog MN · Jun 7, 2011

That is a nice clean job Ron. When you showed the picture of the break I thought it went much lower than that and recommended replacement.
I would repaired it the same way. It should last about forever.

Ron-MO · Jun 7, 2011

Actually the other side away from the camera juts down slightly where the break was. I did not cut it any lower to leave as much material as I could, and figured that part of the break would give some additional surface area to braze rather than straight across. I read up some over the weekend on brazing and welding cast iron, and there are as many nay-sayers as there are people who say brazing or welding cast is no biggie. I have repaired 3 cast iron manifolds now with no problems. One was just one I built up with a wire welder then ground down due to erosion around a port. None of the 3 exibited any signs of cracking like I read about. I believe the previous individual that did this one did no cleanup, and tried to weld right on top of the rust - thus the 'dirt dauber' effect.

Update on 5000 manifold....

Ron-MO

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john_Bud

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Ron-MO

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Ultradog MN

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Ron-MO

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