[Jhjohnson]

Basically i bought a non running 4x4 envoy. The transmission needs rebuilt so i started working on it then was curious as too where the quarts and quarts of oil all over the bottom of the engine came from. Found a tiny hole in the bottom of the front differential that i have no doubt is what squirted oil everywhere. My question is what might’ve caused this? Simply overheating or external causes? And by extension what are the chances i can just jbweld the hole and fill er back up with oil and have it work? Dont really want to replace it but i suppose ill have too with no other options. Thanks all!

 

[NJTB04]

Pull the cover off of the differential and look for any debris that might have got thrown around and caused the hole, chipped gears, bad bearings, etc. If you had noise while driving, you'll probably find some, in which case it will need to be repaired/replaced.
I suspect you'll find some. Repair that, and maybe JB weld will fix the hole.

 

[TJBaker]

Pull the cover off

What 'cover' does the front differential have??

 

[NJTB04]

You’re right, my mistake. Forgot about that.
Maybe you can pull the drain plug and look around.

 

[rustyf99]

There's a relatively large filler and inspection plug which you can use. The drain is relatively small, the diff's are prone to blowing up because they seep their fluid out slowly and no one thinks to check the level.

 

[Ravalli Surfer]

That hole looks like an ejection from a ring gear tooth going out for a look at the outside world.

It kinda looks like the holes I created in the cast iron differential case on my '59 Chevy when I went through 47 rear ends one summer - a long time ago - in SoCal -- street racing for pinks.

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh....... memories!

My buddies were supplying me with used diffs until I found out they were bagging them from cars in the police impound yards.