Hey everyone, I have a 2009 H3 I5. The radiator just cracked at the top at 95k miles so I decided to change out the thermostat at the same time. For whatever reason the bottom bolt ended up stripping out the hole which I drilled, and died up to an M7x1 from the previous M6x1. I was then able to tighten both bolts sufficiently but when I do a pressure test I'm getting leaking at the thermostat.. Any ideas? Was I supposed to use any rtv?

 

Welcome to HF.

My first idea is you should never fix anything that ain't broke, like replacing a T Stat that was working. You probably have a better idea why now?

The T Stat housing seals to the block with an O ring, and it does not need to be cranked down to do that, spec is 10 N.m 89 lb in, which is less than 7.5 ft lbs. Are you sure the O ring was in place and the block surface was clean?



If your new bolt is also loose you may have to use a helicoil and corresponding tap with original bolt and re-do your repair.

IMHO goobering RTV sealant at the T State is not going to do much.

 

Thanks for the reply! Yeah.. I should have let it be.. The new bolt is nice and tight luckily. It was however a very tight fit getting in the new thermostat from the wheelwell so I suppose I should take it off and check out the O-ring again. I didn't move it around or anything from after I opened the box. I bought a new one earlier today just in case it's still leaking when I have a go at it again tomorrow. Thanks