Really??? I have a BMW R100RT motorcycle that uses Helicoiled studs to hold the cylinders and heads in place.

 

Say now...there is an excellent point! Tstat housing is aluminum....head is cast iron. Hmmmm....

 

Sound reasoning but a self tapping screw may not be the best for this application

 

or even get a welder to just tac weld a really long bolt in there with the same thread type, then cut off the end so you have a stud (like earlier suggested) and the you can just slide the housing on and use a nut! be careful with that though, cause it cant be to long cause your drive belt is right there!

 

well after not looking at this since noon, my dad came up with the same idea you have been talking about. we took another bolt and epoxied it in. nice and strong 15hour set epoxy. put the housing over and snugged down the second (good) bolt. and then through a locking washer and nut over the broken bolt. will let dry over night and snug in the morning. then i get to refill and test. (only worry is that the epoxied bolt will hit the drive belt. but thats an easy fix, just grind it)

thank you all for your help and ideas. eventually i will replace the head, or just get another jeep. but for now i think this will work quite well.

 

Unlike some have said, use a small amount of silicone, then tighten it down till it just squeezes out.....walk away for 15 mins.

Tighten again till the silicone just squeezes out......walk away for 15 mins.

Snug the whole assembly 1 last time, I can guarantee it will not leak. Did it all the time at the hot rod shop. End Rails on a Chevy engine with a iron block and an aluminum intake were problematic (that's an understatement). Every time the silicone moves, it leaves behind "firmed" film that forms the seal.

Ron

 

I would still D&T another or two small holes as freegdr suggested. Once that is done, your T-stat housing will stay on and you won't have to replace the head or have it welded. Multiple heat cycles may make the 2 part stuff fail, particularly in a load bearing situation.

 

The ideas just keep getting better. This is the best one I've heard yet!

Just a word of caution: There is a product on the market called duct seal. It is used by electricians to seal electrical conduit from air circulation to avoid condensation at building entry points. Prior to drilling the holes place some duct seal inside the head at the points where you drill the holes. It will contain any metal shavings as they will stick to the duct seal.

 

the two part epoxy i told you about here will not be affected from heat cycles its been used on exhaust b4 with no affect

 

I would agree with part of this if there was more material on the housing itself. You start drilling that aluminum housing, there's not much material left for the bolts to hold. And I don't think you're gonna get a self tapper screw in the head. It's gonna have to be drilled and tapped. There are bolts holding the thing in for a reason, Screws aren't gonna cut it. Atleast not long term.

 

But the head is cast iron. in the area where the outer boss broke of the is casting material inside the water jacket as a provision for and providing a boss for the bottom drilled and tapped hole. As was suggested: If the hole were drilled into the water jacket and a bolt placed from the inside toward the outside and JB welded in it would provide a stud for the t-stat housing.

Now that is thinking outside the box!

 

Gotta chime in on heli-coils... I'm a machinist. I use heli-coils in all types of metal. They are stronger then threads alone in pretty much any situation. They are used a lot in v.w. Pancake 4s when they want to make lots of horsepower because the aluminum or magnesium cases are very thin and tend to distort and strip under lots of heat and pressure. Reason being that the coil is stationary inside the soft metal and the bolt threads into the steel coil. If you install a heli-coil properly with the correct sized hole for 75% or better thread it will be very very strong. And I really like to keep it simple. Looks like there's over half of a hole. I like the stud theory. Clean up the hole thread in a stud and jb the crap outta it from the back side and around it. That stuff is also very strong :-)