Mike,
I Recently encountered a problem with my 1989 toyota 4X4, 4 cylinder 2.2. It jumps out of gear in third and fourth gears, and you can shift it back into gear after it does this, but it'll eventually jump back out again. I was wondering if you could tell me what is causing this.

thank you,
Harry Williams.

Your transmission needs to be rebuilt, you have run it far enough to wear it out. The reason it is jumping out of gear is because the synchronizer mechanism is worn and this is normally caused by the bearings wearing and allowing too much clearance in between the syncro and gear hub.

Mike