Transmission Case Leak, Transmission Case Leak Options

[engine247]

Howdy,

I noticed a newish leak under the car. So I clean up the bottom best I could and let it sit for a bit. The leak appears to just seep through the case slowly but consistently. Maybe a defect or small crack? I'm wondering what my options are here? Only solved with a new case or is there a band aid until this can be bundled with other related maintenance?

Cheers.

[ClayPerrine]

There is a known long term issue with porosity in Magnesium alloys.

https://www.sciencedirect.com/science/artic...142112302000543

"The present work addresses the high cycle fatigue properties of aluminium-containing magnesium alloys produced by high-pressure die-casting and their performance in comparison to similarly produced cast aluminium alloys. A main material defect in high-pressure die-cast components is porosity, which is caused by microshrinkage and by dissolved gases leading to voids. "

What this means to us is that the old cases may start to develop leaks from places where there is no crack or visible hole.

Clear epoxy coatings can alleviate the leakage but you have to have the case spotlessly clean before applying it.

As these cars get older, this is just going to get worse. Casting porosity is the main reason old cars leak oil no matter what you do. Most of the time it doesn't affect the function of the part.

Late 1960s GM turbo 350 and turbo 400 transmission cases had a porosity issue that was due to some casting process defects. A lot of them were replaced under a recall, but there are still some floating around. I found out about it with my first car after chasing a transmission leak for months.

Hope that helps.