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Snapped a stud bolt

I’ve got a 1990 Toyota Corolla and it started overheating today while I was driving it in traffic. I took out the thermostat and upon boiling it in water decided it wasn’t any good anymore because it didn’t open up. It was getting dark, so I put it back together and started the car.

I noticed a leak around the housing that covers up the thermostat. I thought it must need a little more tightening, so I tried to snug up the two nuts that hold it together and snapped one of the studs off with the nut still on it. Well, if you thought I had a small leak before, it’s obvious I have a big leak now.

I realize now that in my haste to put it back together, I didn’t properly seat the thermostat in its gasket.

Is anyone familiar with these Carollas? Does anyone have any good ideas about how to fix this terrible mistake? You don’t need to call me a fool, I already know that.

Drain the coolant and remove the thermostat housing and thermostat (if there is still one in there). If any part of the stud is above the surface, double nut it or use a Vice Grip or similar tool to remove the old broken stud. Replace with a new one. Don’t neglect to use a new thermostat and new gasket.

To err doesn’t make you a fool. We all err.
If you take the thermostat off, there may be enough to of the stud to grasp with a pair of pliers; or, if threaded, put two nuts on the stud (if possible) jam the nuts together, put a wrench (socket) on both jammed nut and see if the stud will turn out.
If the stud broke flush, center punch the stud, start a small (maybe 1/8") drill bit in the stud, use larger drill bits until the largest is almost as large as the stud. If you use reverse drill bit, their action may help the broken stud to back out. Then, use an easy-out in the stud. Don’t put too much force on the easy-out, or you will break it; then, you would REALLY have a problem. (You would need a diamond drill bit (which no one has) to drill out the broken easy-out).

Just a suggestion, before you remove the stud, soak it in PB Blaster to loosen the threads. Make sure you remove all traces of the old gasket from the manifold and the thermostat housing. I’ve used single edged razor blades with success. Also, you may want to put a light coat of non-hardening gasket sealer on the manifold and housing before assembly. I’ve had good luck with the blue RTV and Permatex #2 sealers.

Good luck,

Ed B.

Thanks for the help, the PB and the locking pliers did the trick.

Thank you for the follow up.