I sent a pair of heads off to get done and they came back with out the plug in the one head. What size bolt goes in there?

 

I dont know but i will tell you its not NPT, ive tried!! If you have your water temp sensor take it out and go up to home depot or lowes and put it in the thread checker on the hardware isle if that helps ya out any

 

That may be what I have to do.

 

It's metric, like 14 x 1.5 or some where around there. It's very close to 3/8npt I believe and you can run a NPT tap down it and re-cut the threads. I did that on my dads truck for the mech water temp gauge and it worked fine.

 

Just remember too if you retap it u will not be able to use a oem water temp gauge on there again.... But if your going with aftermarket this will be fine

 

M12x1.50. Found it on tech. But stupid home depot didn't have it. I'll go to Lowes tomorrow and get it.

Thanks for the help guys.

 

Man that is a hard bolt to find. I wound up getting a oil drain plug from oriely's. I didn't think I'd ever find it.