Caterpillar 950 73J3158M. I have just found a crack several inches long in the transmission housing, just above the rear tailshaft. At some point in its life, something bad has gone wrong with the trans or engine mounts causing it to sit way too low and one universal joint to just slightly rub on the trans housing, and two trans bolts to rub on the rear axle trunion. I don't think this has anything to do with the crack, but it possibly might. Whatever happened was fixed before I had anything to do with it. Is a crack like this common on an old 950? Ignore it and just put up with the oil leak? Remove tailshaft, grind out and weld up? Remove transmission, dismantle completely and weld up?
i suspect something tried to eat its way out from the inside at one time or the u-joints failed and the assembly flailed against the case but there should be a few gouges and scrapes in the case. you could possibly clean and prep the surface and smear some kind of sealer over the crack. a flexible type of sealer may work better than a rigid type of epoxy because of the vibration. the permanent type of repair would involve removing the trans, disassembling, and then having the crack repaired by welding, etc. all sorts of issues from previous failures can be found on a lot of old machines. it keeps things interesting
Rear axle trunnion bearings are bad or have been bad allowing driveshaft joints to eat on tranny seen it many times when the trunnion bearings havent been greased or the lines are broke and grease pumping into belly pan
Allso check the trans rear supports on each side to make sure they havent came loose but im betting the trunion bearings are or were the cause
I have no idea how that happened, but I know what I'd do. Put a light vacuum on the inside of the case, clean it with brake cleaner, and epoxy it, watch and if it sucks the epoxy through wipe more on and shut off the vacuum. If it flexes too much for epoxy, then you have bigger problems. You can always put RTV silicone over the cracked epoxy, won't that look nice?
Vee it out just a touch then weld it "I like Nickel" a inch at a time then peen the hell out of it "the inch at a time and peening keeps it from cracking" BIG thing with cast dont get in a hurry
I use Nassau Rockmount Jupiter A rod for stuff like that. High nickel content. Rockmount has saved my butt a time or two, so I drink their koolaid. But, that sucks and looks expensive. Bummer.
If you can get it clean and dry and keep it clean for a few hours, as in draining the oil out, 3M window weld urethane applied in a nice thickness may well hold oil. Years back I had a 38k top loader Mack rear housing that did the typical driver side bolt circle crack. I ground it out and welded it up but I never could get it flat enough to seal up. After taking it out for the 4th time, I window welded it with urethane and that was the end of the leak. I pity the poor soul who had to take it back apart.
We had a really good convo recently regarding a cracked differential housing on a 12F grader. She even has a name. Can’t think of it. ... maybe it was Hanna? Helluva blade, old Hanna. Seriously, lots of good information was shared.