More Cooling System Overhaul Issues: Broken Thermostat Housing Bolt In Engine Block

Barely Krawlified

Barely Krawlified

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Well, fresh off of my triumph over the fan clutch bolt, the Jeep gods decided that I am to overcome another challenge to this damn cooling system overhaul. The issue: Snapped off one of the thermostat housing bolts in the block.

Here we go again…Suggestions???

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There are numerous ways to remove that piece.
You can try tapping the remaining bolt threads CCW with a chisel, but you risk the chance of marring the gasket mating surface.
You can center punch and drill a small hole in the bolt then use an easy out to remove the piece.
You can place a nut over the broken bolt and tack weld the nut to the broken bolt; the heat could loosen the piece and the nut would spin the piece out easier.
 
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Well if you have to mess around with a broken bolt, that's a good spot.

If you go the center punch and drill route, grind the end of the bolt flat before you center punch. This will help you immensely in getting it punched and drilled properly. And really take your time to ensure you punch it in the center. When you drill make sure you are drilling straight through the bolt and drill it all the way through.

Once you get it drilled all the way through shoot some good penetrating oil in the hole and give it some time to work. Use the largest extractor you can and be gentle.

If it doesn't want to come out, and you drilled it really close to center and fairly straight, you can drill it incrementally larger and stop before you get into the thread in the head.

At that point you can carefully chase out what's left with a tap.

If it was mine I would pull the radiator for more room.
 
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Barely Krawlified said:
Well, fresh off of my triumph over the fan clutch bolt, the Jeep gods decided that I am to overcome another challenge to this damn cooling system overhaul. The issue: Snapped off one of the thermostat housing bolts in the block.

Here we go again…Suggestions???

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Man I’m glad I’m not you. That just looks like pain. I wish you the best. I’ve been there messing with cracked housings and poor mating surfaces, but that’s a new one by me.
 
Thanks for all the replies and each one is appreciated.

When I went to finish tightening up the bolt that broke, (by hand, small 3/8 ratchet as well) I wanted to make sure the housing was tight/flush against the gasket/block to guard against leaks. Once I heard that distinctive “pop” and felt all the resistance dissapate from my wrench, I immediately felt what my wife calls the “heat of shame”.

It’s the realization that you done messed up big time and that not only are you done for the afternoon but that fixing the problem will require time, money and probably a little bit of good luck too.

The bolt was one of the two original thermostat housing bolts so after 20 years of repeated heat cycles I guess it was a bit brittle.

I phoned a friend on this. He took a look at the photos and said that he could help this weekend. Luckily my TJ is a 3rd vehicle so it can wait. But damn…it sucks.
 
If you broke it overtightening you might be able to grab what is sticking out. Or cut a slot in it for a screw driver.

There is a torque spec for those bolts. Use it :D
 
since it broke from over tightening, use the smallest available Dremel cutting blade to cut a groove thru the middle where it’s thickest and then try using a flat blade screwdriver or chisel to back it out.
 
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