Power gilde tranny
 

My son in law has a 57 chevy with a 283 mtr and a power glide tranny. I all of a sudden stuck itself in low gear and we can't seem to get it to release. I'm hoping one of you might offer up a few things we can try.
Thanking you in advance,
Bill

Re: Power gilde tranny
 

This PFD is for troubleshooting cast iron powerglides.
http://www.567chevyclub.com/images/5...powerglide.pdf

If it happened all at once I'd suspect a defective governor or stuck shift valve.

Bad clutch plates you should be able to smell the burned clutches when you smell the fluid.

Looks like that is the complete powerglide section out of a shop manual. It has the repairs and adjustments as you scroll down the page.