Stripped thermostat bolt
 

200 Mercury EFI. Anyone repair one of these? Looking for best option: HeliCoil or next size bolt? Currently a 5/16-24 bolt. Not sure if there's room for a 3/8 and not sure of grade of bolt. Pretty common problem on these aluminum heads so i'm sure someone has tackled this on here. TIA

Stripped bolt
 

PM Monatauk ... i believe he used to work on merks at prop shop...

Is it possible to rethread the hole?


sent from my Galaxy NOTE II

left hand drill bit and extractor then rethread

If the bolt broke that may work. I don't think you need a left hand drill bit though.

If the threads on the bolt stripped try using the tap that is the same size and thread as the original bolt to clean the threads in the hole out. If this does not work you could try and re thread the hole with a courser tap.

a lot of times in aluminum using a left hand bit will back the bolt out then you just need to chase the threads with a tap

Yup, done that on a valvecover stud before, works really good.

You can rethread hole to original size. Cut you a piece of allthread the length needed. You will need some thread epoxy ( Advance Auto Parts ) double nut stud and install with epoxy. I would let it set overnight and the install thermostat cover with a nut & washer. Good luck...