I did try the thread sealant, high temp, same stuff i used on the number 11 head bolt, we will see how it goes with that. IT went on last night and i am giving it a true 24 hours to dry/set up in there.

 

As a reply to an earlier post, you're not going to be able to weld cast iron.

It's so tight in there I doubt it could be brazed, either.

Thread sealant might work, but coolant has a nasty habit of sneaking out anywhere it can find a weak spot.

You may end up transferring your new parts to another head. Bummer.

 

Indian Head shellac is more of a gasket sealer where Permatex #1 and 2 series are more of a thread sealer is all I'm thinking. And, the OP already has some left over from #11 bolt. Heck, if it doesn't work, take it off and do it again, I guess.

Please report your findings Guntar13.

 

Yeah, I agree. We used to use permatex on boilers,similar application and ++>212 degrees for 24/7.

 

If the sealant doesn't work you might be able to fabricate a cover plate out of steel stock, have a machine shop drill and chamfer it to accept the thermostat and drill it out so the bolts pass through. Seal it up good to the head and use it as the new thermostat mount.

 

If the stuff is good enough for the #11 bolt, it's good enough for the thrermstat housing. Here we are discussing it and I'll bet Guntar13 hasn't reported back cuz he's out driving around!!