View Full Version : Broken thermostat bolt

07-28-2007, 04:04 PM
I broke one of the bolts that hold the thermostat housing on.

I have tried to drill this bolt out but this bolt has to be made of the hardest material ever.
I have even tried cobalt drills but it barely makes a dent.
Any suggestions?

07-28-2007, 05:14 PM
If you broke it putting it on, then there might be a nub left over that pliers can grab. When I broke a rocker arm bolt off, the two halfs fit like a "jigsaw puzzle", I was then able to push the bolt head down onto the other peice and turn it loose.

Just a thought

07-28-2007, 09:00 PM
I thought this stuff only happened to me!

Did you break it trying to loosen it, or was it from being tightened.

A crusted bolt might respond to PB blaster, and some careful work with a punch and hammer. I have a trick that an old timer showed me for crusty breaks. Put your punch in a holder or some vise grips, Take a little ball peen hammer and hit the punch with will quick an rapid hits (like a wood pecker).
Put on some more blaster and tap again--repeat several times. Its sort of like an ulrasonic bolt loosening treatment. Some times it works!

An overtightened break is usually in so tight that drilling and hopefully an easy-out will save the day.

Carbide may be your only way to cut it out.

07-28-2007, 09:05 PM
your drill bit is likely dull. Get a reverse twist drill bit and drill it out with that.

If you have a dremel with a new cutting disk you might be able to cut a slot in the head of it to try a standard screwdriver.

07-28-2007, 10:11 PM
Thanks guys.
I broke it taking it off. It sheared a little of the way in so there is no way to put a slot in it or to get a punch to it.
The drills are brand new. Some were reverse. Broke a bunch of them trying to drill it out. I'm done for now, will try again tomorrow.