Welding Tips and Tricks

I've got an old aluminum Chevy bellhousing that has several cracks in it. I'm looking for some tips on cleaning and welding the cracks. My cleaning process, degrease, glass bead and use a torch to heat the cracked areas to maybe cook some of the crap out of the crack? Use a die grinder with a tree bit to v the crack a little bit. Wipe down with acetone prior to welding.

I have a lincoln 225 square wave tig machine for welding. AC balance has me concerned on how much to use. Start out around 70% cleaning maybe? Would 4043 filler be sufficient?

Thanks for any help.

What you have planned sounds pretty good. The only thing I'd add is that drilling through the end of the crack is the only real way to stop it from propagating. In addition to notching it out, you might as well run a cutoff wheel down the crack too. The 1/16" gap will make life easier in the end and help eliminated contaminants stuck in there. Also be sure not to use chlorinated brake cleaner...

-Sandow

Be sure to bolt it to the back of a block so that it doesn't move around too much. If the hole in the center of the bell housing doesn't line up with the center line of the crankshaft then you will have bearing problems in the transmission. About .005 run out is all that is allowed.

I would drill each end, V one side with carbide, then weld. Go to opposite side and use carbide burr down to clean metal and weld.
I feel if you grind the crack with an abrasive wheel you leave some debris behind plus you open the back of the weld to air and you may need to flow argon to the back side.

Curtis

Thanks for the replies fellas. I most definetly will have it bolted to a block when I weld the cracks. I won't get to this job until next week sometime but I'll be sure to post pics for people to refer to in the future.

I'm going to build a engine test stand and needed a bellhousing. I've had this one laying around for years so I figured it would give me some good practice welding AL and I could leave it with the test stand. 2 birds, 1 stone.

We all love pics. Some will even say, Pics or it didn't happen. Lol

Curtis

Just curious, but are you sure that it's cracked? I've got a few aluminum Chevy bell housings that look like they are cracked, but it's actually just lines from the die casting. I thought they were cracked until I took a closer look.

big gear head wrote:Just curious, but are you sure that it's cracked? I've got a few aluminum Chevy bell housings that look like they are cracked, but it's actually just lines from the die casting. I thought they were cracked until I took a closer look.

Oh yeah these are cracks, no doubt about it. They crack from not being installed properly. Most of what I ever experienced was guys installing them and not making sure the mating surfaces are clean.

Do you guys suppose a 1/8" bit will be sufficient for a stop crack hole ?

Also, should I preheat the bellhousing or just bolt it to the block after its all cleaned up and weld the cracks ?

I'd go up to a quarter at least. It can be hard to see exactly where a crack ends and holes are easy to fill.

-Sandow

I've welded them without pre heat, but I don't think it would hurt to warm it up some. If you concentrate the heat on the cracks it can help pull some of the oil out of the casting.

Search Tamjeff on this forum, He is the finest aluminium repair man I've ever seen, Shows a very good method for stopping shrinkage cracking as well.

Mick

Did the ear crack off or is this actually up in the cavity area?

Thanks for the replies fellas. The cracks go from the outer edge of the bellhousing in towards the mating surface of the transmission.

I have a question from the replies. It was mentioned to drill holes at the crack ends, but I thought that was for cast iron. Does one do it for aluminum castings as well.
I also remember seeing some Youtube videos on welding cast aluminum, perhaps that would help you as well.

HitMissTom wrote:I have a question from the replies. It was mentioned to drill holes at the crack ends, but I thought that was for cast iron. Does one do it for aluminum castings as well.
I also remember seeing some Youtube videos on welding cast aluminum, perhaps that would help you as well.

Same reasons in both cases. Cracks will continue to propagate until they are terminated in some way and it is usually best that it not be the far end of the casting. If you don't drill the ends out, the heat from welding, regardless of where you start, will probably cause the crack to grow do to differential thermal expansion. Round holes have more or less omnidirectional stress loading so they won't originate new cracks while giving the current crack no place to grow through. From the engineering perspective round holes are good and square holes are bad for pretty much the same reason.

-Sandow

I usually match the hole diameter to thickness. That way you get full prnetration. Plus like Sandow said, you don't want to miss the end, if you see you missed just use a carbide burr to get it.

Curtis

Thanks guys for the hole at the crack on aluminum. I am never to old to learn something new!!

[img][IMG]http://i103.photobucket.com/albums/m135/Team_Torch/7CC1252B-26DE-498A-935B-BE96FBF6781C_zpssrb73ysr.jpg[/img][/img]

Bellhousing cleaned up for better inspection and repair.

Stop crack hole drilled and 1 side of crack v'd out.

Not the prettiest weld but I'm confident it'll hold.

Inside of bellhousing v'd out for welding.

Inside welded up. Not the best job but it will work.