Welding cast iron??

[John White]

I just purchased a tractor and it had a backhoe on it and someone hit something and cracked the diff. housing. It is a small horizontal hairline crack about 6" long on the round part of axel tube on bottom. Fluid seeps out of it. I know first off that I will have to get the fluid drained. I haven't looked at it yet very well (just got it) I might have to drill a small hole to drain it, tap and put a plug back in it. I will leave the welding to a professional. But I am sure it will have to be in my shop due to having to take every thing off. Will they tig weld it? How will it hold? Any special procedure. Sorry I don't have a picture.

 

[Motorboatin]

I would have it brazed

 

[Topzide]

Call around to a mobile welding outfit and get some prices. From what I know, they could stick weld with a nickel rod after preheating. Look for any nearby seals as they may need replacement after fix is done. Not sure about Tig, had an exhaust manifold welded many years ago and held up till I parted way with the car. Will need to be dry and clean. If you can get dry and prepped, might help in pricing. Good luck and enjoy your tractor!

 

[zzvyb6]

I just purchased a tractor and it had a backhoe on it and someone hit something and cracked the diff. housing. It is a small horizontal hairline crack about 6" long on the round part of axel tube on bottom. Fluid seeps out of it. I know first off that I will have to get the fluid drained. I haven't looked at it yet very well (just got it) I might have to drill a small hole to drain it, tap and put a plug back in it. I will leave the welding to a professional. But I am sure it will have to be in my shop due to having to take every thing off. Will they tig weld it? How will it hold? Any special procedure. Sorry I don't have a picture.

You presume it's cast iron, could be cast steel. That would be easier and 'better'. The crack WILL be 'contaminated with oil residue, so cleaning it will be mandatory. Even if cast steel, preheating it should be done. It can burn off the contaminates and allow for a stitch stick weld using nickel rod. Yes, stop the crack and open it up.

Keep in mind if welding is done on the inside, too, so bearings, pins, seals etc don't get 'bothered' by welding flash. Once, I had a cast gear shatter on my NH 1012 stacker when the 1st table got jammed and the crank arm broke the cast iron drive gear into 4 pieces. I used my Sears buzz box with nickel rod and welded it all back together, including filling in some small missing pieces. Preheated in the barbecue grill to burn off the grease, paint and get the thing red hot. That gear is still on the machine and works fine after more than a dozen years. I bought the replacement and never installed it. Nickel rod is very hard. Grinding off the excess took longer than the fix.

 

[PILOON]

I once had a cracked exhaust manifold brazed and that stood up for years.
They brazed it while still in place.

Now that was on a 60's 6 cyl Plymouth that had actual space under the hood and no plastic parts unlike current cars that U can't find the actual engine.

 

[flusher]

Cast iron or cast steel? This YouTube video shows you how to tell the difference quickly

IS IT CAST IRON OR CAST STEEL? 5 Ways To identify Before Welding - YouTube

If you can't get the part off your tractor, just skip weld (1" long weld, 1" skip) with the recommended weld rod and let the part cool to near room temperature between welds to prevent excess thermal stress from building up in the weld area. Drill a small diameter hole at each end of the crack to limit crack propagation. Clean the part thoroughly and grind a U-channel along the weld to get better adhesion and weld bead strength.

Good luck

 

[Motorboatin]

The problem with brazing is that a lot of people don't know how to do it so they just jump to welding. Brazing in this situation is ideal since it's supposed to hold fluid and being leak free is the goal

The problem with welding cast is that just about everyone claims they know how to do it yet they don't actually know what they are doing. Having a pin hole leak is far more likely

 

[yomax4]

Getting the oil chemically removed is key. You may be able to burn it out with your torch. You also have to stop the crack from spreading via drilling holes at the ends of the crack. After that it can be stick welded with Nickel, 312 Stainless or Brazed. It sounds like it will be an overhead project so brazing will be less than easy. I have some Nickel Silver brazing rods that flow very thick for these types of repair. They work well overhead. Still, Stick welding might be the easiest Or if you have access to a spray powder set up use that ! Good Luck with the project !

 

[PILOON]

For sure stop drilling is a very critical step.

For cleaning (degreasing) MEK, carbon tet or even laquer thinner usually do a good job.
The pores of the metal need to be cleaned otherwise any weld will not perform as it should.

If a part to be welded can be removed then steam is also a common degreasing procedure.

 

[MinnesotaEric]

I just purchased a tractor and it had a backhoe on it and someone hit something and cracked the diff. housing. It is a small horizontal hairline crack about 6" long on the round part of axel tube on bottom. Fluid seeps out of it. I know first off that I will have to get the fluid drained. I haven't looked at it yet very well (just got it) I might have to drill a small hole to drain it, tap and put a plug back in it. I will leave the welding to a professional. But I am sure it will have to be in my shop due to having to take every thing off. Will they tig weld it? How will it hold? Any special procedure. Sorry I don't have a picture.

You can weld cast iron, but right where the weld meetsa the cast iron is going to be your weak point. Heating up the cast iron before welding it really helps.