I've got a stripped oil pan bolt hole. Does anyone know what size tap and insert to use to fix?

 

M6x1.0

if its not on a corner then you can survive without it. you wont be able to use an insert like a helicoil or anything. if its in rotor housing you may get away with stepping up to an m7 but if its in an iron, i wouldn't take that risk. you can try installing a stud and seeing if it will catch after a retap and put a nut on it. the torque value isn't that high so you just need it to grab enough. again though, if its not on a corner i wouldn't worry about it if the tap doesn't save it.

 

I was thinking Helicoil to try to permanent fix because it leaks. Is there not enough material in the housing to support a helicoil? It's a rotor housing bolt hole.

 

An m6 helicoil is huge relative to the working area and requires a large and deep hole to be drilled. It's just not a recommendation I would make. An m7 or 1/4-20 bolt would be a much safer alternative if you can't get the m6 threads to restore.

A standard 1/4-20 bolt is ever so slightly larger than an m6 so you would tap it for that thread pitch. You shouldn't even need a drill. Slowly working the tap should ream the hole out just enough.

 

Understood. Thank you!

 

I don't think this is necessarily true. The OD of a M6 helicoil is only 7.7mm. My OCD would flair up if I had 1 bolt that was different than the rest.
Maybe you are thinking of a keensert? Those are quite a bit larger and may or may not fit, but I don't think a helicoil would be a problem at all.

 

Just use a stud that has 1/4 20 for the inserted side and 6mm for the other. Red Lock Tight the 1/4 20 side and don't have to worry about it again.