i have a 3 inch hairline crack up the backside of my case i was wondering if anyone has tried welding them on a pro drive also the same with the sump cover. any help would be great.

I had a kohler welded up. It's worth a shot. Just need to make sure you get the aluminum really clean. Bolt the case together and tack the cracks in a few places to hold it together. If you try to weld it with the case separated, it's going to expand and you'll never get the case to fit back together. You should be able to weld it the length of the crack on the inside and outside. Just go slow. Don't try to run a full bead on it in one pass. Let the metal cool.

drill a small hole at the begining and the end of the crack and grind as much of the crack as possible. Use a tig machine and slowly heat the case and burn out all the impurities before you deposit a weld. Do a little and let it cool. Thats how I do lower units on outboards. No reason you shouldn't be able to fix it if you have good access to the crack................On second thought, no way you can weld it! I'll do you a favor and give you scrap price for the whole thing!!!!

Hey cb,
Did you totally take the engine apart or can some stuff stay? Can you just take the cam out and leave the crank and piston's in?

If you leave the crank in, it'll be awfully hard to weld inside. I completely tore the motor down. Ran like new when we were done. Once you have it all broken down, it only takes a few extra minutes to remove the pistons and crank. Just make sure you label them, so you know which rod/piston is on cyl 1 and which is cyl 2 when you put it back together. I completely tore it down and brought my welder just the bare block and sump cover.

Ruddyduck is spot on about stop-drilling the crack. Forgot to mention that. I would stop-drill it before applying any heat to clean it to keep the crack from running when you get it hot.

I have never tig welded cast aluminum but i have stick welded it. Any cast metal must be very hot to weld good. I always take a torch with a rosebud on it and heat up a little. But dont get to hot!!! I have welded up many 4 wheeler blocks that are still holding