The Stovebolt Site Forums The Shop Area General Truck Talk Welders need your help

I'm putting together a 68 1/2 ton longbed, 350 V8 with ram horn exhaust manifolds. The right side manifold has small little cracks at outside wall just below collector tube.
Question: Can these cracks be welded closed? or should I just junk it? They don't seem to go all the way through, but might expand when engine runs. Might is not the right word , they WILL expand, and tht's why I thinking welding may not work. But I'm not an expert.

What do you have to loose?
I welded a completly broken in two exhaust manifold for our john deer tractor with some of that nickel rod they sell at tractor supply for cast iron. I warmed the whole thing real good on the wood stove and with the torch, then welded it and left it on the stove to cool slow as the fire went out. The tractor vibrates a lot and it has been a few years now and it is still holding fine. The whole end that holds the muffler up out of the hood broke, so it is not like it is bolted to the engine and cracked again but still on there, if it crackes again the muffler falls off.
Give it a try....
Grigg

And i am not a profesional welder, I took a night class at work for a few nights a week for about two months, just enough to learn how to stick weld nicely.

37lookin - you can arc weld cast iron with nickel rod and it works well. It is often used in large truck blocks to patch holes and cracks. Since big diesels are megabucks to replace.

But! and this is a big BUT!

If you have a crack. You must drill a small hole in each end then weld it. If you do not drill the hole at the end of the crack, when you heat the metal, the crack will expand and continue to grow. The weld is more of a brazing process than welding, so its not actually welding the metal but attaching the metal like soldering.

If you do not prepare the crack by counter drilling, you will have problems later.

In the instance given above, there is no crack to expand. So the nickel rod should hold well. But with a cracked block you need to stop the crack. The weld wont do that on its own and you will have problems later.

It is also recomemended that you only weld about a 1/2 inch at a time, peen the weld with a small hammer (lightly) for stress releif and then weld the next 1/2 inch untill you finish.

If done correctly, the weld should hold for many years.

buzztrader, did you get that off of one of my previous posts? Just kidding .... I heard about that method via the grapevine from an old timer. Your post is the only other time i've heard it explained that way. Oh, and that old timer said he repaired a crack on an engine block on a tractor and it took all day!

So, anyways, folks, buzztrader is right on the money.

Yep, that's about right. Relieve the stress on the crack. If the manifold is cast, heat it up and then weld. Cool slowly.

I have welded them up with MIGs too. ALways have worked just fine. They are fast so the heat stays localized. I have even welded shock mounts on my 1 ton axle and they are still holding on fine with a MIG as well. (Actually flux core wire welder)

Can't emphasize the preheat and postheat enough,
get it hot before welding and keep it hot after. at work we had a oven we would put welded cast parts in overnight then cool down gradually after that.

Can all this be done useing Oxyacetylene ?
That's what I have.Some of you mentioned arc and MIG
Thanks for the info.
Chris

You can drill out the start and stop of the crack, grind the crack out [grove a v in it] then Braze it. Make sure its SHINIE BRIGHT befor you weld or braze. Both pre and post heat is imporent. Been doing it for 35 yrs. retired now, and just did my ex. manofold on my 53 3/4 ton. Paul

Francis hit the nail squarely upon the head, don't mess around trying to weld it, do just like he says and BRAZE IT. Welding MAY work, but brazing WILL work.

I have also seen more cast iron successfully brazed than welded,,brian

Brazed a crank journal on a stamping press that broke. the weld was 16 inches deep. it held.