Q: Th350 transmission leaks out of thr vent. On 1977 chevy k10

asked by on July 09, 2017

I just had my th350 transmission rebuily. I put it back in filled it up the correct way went and put it through the gears then started to back up and transmission fluid started leaking out of the vent hole. ( I have the granny tunnel off so I can watch it happen ) it only leaks in reverse. I tried taking fluid out but then it wouldn't drive right and it still leaked. I drained as much as I could the slowly refilled it but it still leaks out of the vent in reverse. I have searched the internet and can't find anything. I'm about to talk to the guy ego rebuilt the tranny. I really don't want to pull it again. My question I guess is why is my th350 leaking out of the vent??? Its not over filled.
My car has an automatic transmission.

It sounds like it may have originally been over filled. Fill 4-5 quarts, then start the truck and then slowly fill up the remaining fluid. This should keep it from leaking from the vent hole.

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