Differential problem

Had to swap a tranny yesterday, belongs to a friend of a friend. Was leaking oil, sight unseen assumed rear main, but upon inspection, was transmission fluid, pouring badly from the bell housing.
Took it apart, and voila.



Wife who was in the car at the time said she heard a loud bang, then noticed the leak when moving.
The shape of the hole says to me something wore or broke through from the diff side. It has a circular portion on the left side of the fracture. Anyone see this before?

There is a differential pin that lets go and tears through the case.. its not too common but fairly common you can find info about it if searching.

"self-machining" , as in "self-machining case", is the common phrase and might work well for search purposes.

Yup! VW has had this problem for 20 years..... Certain 020's were very prone to it.

Saturns used to do this as well.

Poor diff pin retention design, and the diff pin wants to escape by smashing its way out of the case.

Usually happened to drivers with a more aggressive style, or if the car had been stuck in snow or mud lately.

Vince Waldon said:

"self-machining" , as in "self-machining case", is the common phrase and might work well for search purposes.

Click to expand...

Describes it well, has an arc so I knew it had to be from a rotational something.
Issue popped up in my own car recently, starts fine except when sitting overnight. I bang on or turn the steering wheel and it fires up. Ignition module? This morning it wouldn't go at all, popped the hood, maybe the slam shut got it going...