Crack in bellhousing
As a certified welder “IF” you want to fix it
1) remove the bell housing completely and clean it spotless.
2) you need to pre- heat the cast to 400 degrees. A kitchen oven is perfect.... hense the clean it spotless.
3) drill the end of the crack with at least a 1/8” drill bit slow and steady so you don’t break the drill off in the hole. Drill all the way thru. I like to step it up to 1/4”
4) Go to a real welding store like Airgas or basically a welding supply store that only sells welding and cutting equipment. Places that sell Forney welding supplies typically hardware stores are not a good choice and the people have no experience in this matter but “I know a guy” stories. Forney stuff could be sitting on a shelf for years collecting dampness. There products are marginal at best and again old. You want new fresh welding rods. Typically referred to as “Ni-rod” there are different grades of cast welding rods. Based on make up of metal. Tell the counter guy you are welding older automotive cast steel. They will put you in the right direction.
5) grind the crack in a “v” with about 1/8” left at the base. The top of the “v” should be about 3/8” wide. Don’t grind thru the base metal.
6) put your “spotless” cleaned bell housing in the kitchen cold oven. Turn on the oven to 400 degrees and let bake for approx 1 hr minimum. (Wife will question or debate this process) have a old blanket ready.
7) leave oven running and after 1 hr remove the part. Wrap immediately in blanket to keep warm.
8) following recommendation by weld rod manufacture weld up the cracks using AWS D1.1 procedures. (I know a bit much but I am a professional welder)
9) after done welding - keeping blanket as much on the part as possible to keep as close to 400 degrees as possible. Bring back to oven and remove blanket and put part back in. Run oven for 1 more hour at 400 to stabilize part heat zone.
10) shut off oven and do not open the door and then allow to slowly cool - I typically allow over night.
If you do everything correctly it will weld properly. If you don’t- it will re crack.
This is why most choose to buy a different part. A lot of work for possibly little reward. My clients and customers typically think welding cast is a walk in the park but it is far from that.
Joe
Awesome advice!
Cudos to you for explaining this process so well.
As a journeyman welder myself, i have used this exact procedure with excellent results.
I have repaired all sorts of castings such as bell housings, exhaust manifolds, cast iron transmission pans, etc. with Ni Rod and it works great.
I have used brass rods and have done it with a torch as well.
The Ni Rod is my preference.
If you don't have Ni Rod, you could use a 308 stainless steel rod in a pinch.
I usually would weld only 1/2'' at a time and use an air peaner to pean the weld.
In the field, i would heat the part to a dull cherry red with a rosebud tip 4'' or so around the crack and weld it up.
After welding, I then would put the part in a wooden box and wrap the part in insulation and leave over night to cool slowly.
Do not use the mig, unless you have no other alternative, and if you did, use lots of preheat and hope for the best.
