Hey I was changing my thermostat back to a 195* one when one bolt from the thermostat housing came out a little rough. I looked at the theads and they were a little messed up so I used a 5/16 die and ran in up an down the bolt. Threads looked perfect!! Placed both bolts in and tightened one up about half way and tighted the other up half way. Tightened the first one the rest of the way and tried to do the same with the one I cleaned the threads on. After about 5 turns with no resistance I thought something was wrong but figured it was the new threads going in easier. No such luck 2 more turns with medium resistance and pop the damn head broke right off the bolt!
I took everything back off stuck a rag in the thermostat hole and got an easy out and some drill bits. Did not work!! I got a nice hole in the middile of the bolt but cant get the easy out (round ones) to bite.
What should I do???
I thought about just drilling the hole out with a 5/16 bit which is the same size of the bolt then running a tap in and out of it.
Does anyone know if those bolts go into the water jacket? I dont think they do.
What would happen if anything if I where to drill completely through the hole where the bolt goes and come out the bottom where it bends back in? Help!!

 

do you have access to a welder and some pulling rods?

if not...what about a simple pair of vice grips?

 

well, first i would start off by making darned sure that that easy out has sharp edges....life will be a lot easier if it is, then i would beat that easy out into that bolt with the proper hole diameter its made for so every possible tooth would catch. --there is also a trick to drill with a slightly larger bit only a little ways into the hole so the easy out will catch on two edges because the easy out is cone shaped.---or you could find the right size cone shaped die grinder bit to get maximum bite for your easy out. next, soak the **** out of that bolt with some kind of liquid penetrate....if that doesnt work, get a pencil torch and heat the darned thing, but you have to be very carefull around that aluminum. i would just heat the bolt. i want to say that im 85% positive that the boltsdo not go into the water jacket....otherwise youd have leaks around your bolt heads. GOOD LUCK!!!

 

just based on memory, i think the t-stat housing bolts do go down into the water jacket. do you have anything sticking up ? if so try to grab it with vise grips. if not, check that your ease outs are sharp, and that your hole is the right size. another idea is left hand drill bits with drill in reverse of course. those continuously try to unscrew the bolt. otherwise just keep drilling bigger holes and keep trying ease outs. eventually one will grab. try to keep shavings out of the water jacket.

 

i had one of these when i did an intake, if you can get a grip on it but it wont turn try heating it up. redhot and see if that works. i put my torch on it and had that sucker off in 30sec. after i beat it with everything it could tyhrow at it for two days.

 

if you have any star bits try to hammer one of them down in the hole like you would an easyout, sometimes works better and gets a better bite.....sounds like your hole threads needed cleaned

 

I tried left handed bits and a round easy out so far with no luck yet. There is not any bolt protruding so I cant just grap it with vice grips. I got a good hole started dead center of the bolt. I just went and bought a new square easy out and 2 new drill bits (cobalt).
If I cant get it out why could I not just get a 5/16 drill bit (same size of the bolt and drill the remaining part of the bolt out without going down to the unthreaded part of the bolt (the last 1/4 inch if that), then just rethread the hole with a 5/16 tap and use a 5/16 bolt without the unthreaded part?
Any pros or cons with doing this? It is driving me crazy.

 

youre gonna have a tough time getting it exactly centered.......you could try a tad smaller and try to break the threads out

 

Yeah I think I will try to go a bit smaller then 5/16th if I end up trying to drill it out that way. Hopefully the new easy outs (square ones) I got will be good. I really need the rest of the bolt to unthread so I can get out that little part at the end of the bolt that has no threads.

 

this reminds me of the bolt that i broke installing my exhaust manifold. one day i plan on welding a nut onto what is left of the bolt and get it out.