This problem is on my 2007 2.3L 4 cylinder. Does anybody have a method for getting to and removing a broke off thermostat mounting bolt. It was the first one, so I stopped before breaking off the remaining 2! I was using a 1/4 inch drive socket wrench, so I was not apply hardly any pressure at all. I sprayed it down with Kroil after that happened (yesterday). But before I go onward, thought I would ask for help! HELP!

 

Not much you can do except replace the engine..........................joking

Take the 2 other bolts off, and remove housing, if they break they break at this point you need to extract one so a 2nd or 3rd will be that much easier once you have the tools to do it

The bolt goes into an aluminum casting so not uncommon for previous owner/mechanic to cross thread a bolt so it either breaks going in or coming out, you may have run into that here

After housing is off you can see "where" the bolt broke
Did just the head come off so shaft is exposed?
Did it break flush with casting?
Did it break inside casting?

You can Google: extract broken bolts

Almost all will have to do with car engines, lol, as its a fairly common issue on vehicles

Basic step is to DRILL the bolt out, BUT use a Reverse-able drill and Left-handed Drill Bit, the reason for this is because the vibration of drilling and the reverse direction often loosens the bolt and it unscrews while drilling it
You start with smaller drill bit and then use larger and larger until threads release grip

Tight spots may need a 90-deg drill attachment

Hole will probably need to re-tapped(re-threaded) after bolt is out, threads should be cleaned in any case

You may not have this equipment, and won't ever need it again, so like in the Movie "Magnificent Seven"(the original, lol), you don't "buy the guns", you "buy the men with the guns"

There are mobile mechanics that might be cheaper in the long run and will already have the tools to extract the broken bolt.
If vehicle is still drive-able, then local shop might be able to do it, but mobile mechanics are often cheaper because of less overhead

 

Thanks RonD for the fast and detailed response. I should have been more specific as to my question. Under ideal conditions (as all the YouTube videos demonstrate), you have a broken bolt or stud laying there in front of you on your part on your bench. But this stuation is different. The offending thermostat is on the driver's side of the engine halfway down in between and behind a lot of stuff that looks like brake lines going to a manifold or valve- barely enogh room for your hand/arm and you can not get a straight shot at it from above. I am wondering if I take the wheel/tire off and remove something else if it will improve visibility/access to the thermostat region though the wheel well? I have in the past removed a good number of broken fasteners, so I do have the tools. And I am grateful for your advice, RonD! I will go for the remaining 2 bolts and see what happens. The one I broke I am pretty sure broke flush with the block because it has a bit of the bolt shankattached to the head that looks about as long as the thermostat's bolt flange is thick. It was the upper left bolt and has a rusted head. The other 2 bolts are on the right side, and it appears the top bolt is not rusted, but the bottom one is. Not sure why that would be so, but hopefully they both come out without snapping!

 

Some disassemble will be required, and you should change the PCV Valve while you are in there, it is accessed via the drivers side wheel well, its located in middle of engine drivers side where oil pan and engine meet.
You're suppose to change it once a year, lol.

But no, no tricks that I know of to remove a broken bolt except drilling it out, and making enough room to get drill in there, at least it should be a softer metal bolt, not sure but certainly doesn't require hardened bolt for this application, but maybe that's WHY IT BROKE, lol.

 

Well thank you once again, RonD, I am going to get back on this next Friday evening after work, so i will get back on here next weekend with a progress report and hopefully a success story! In the meantime I am probably going to occassionally marinate the thermostat bolts with Kroil to "tenderize" them a bit more. I need this truck running, and I really don't have a lot of extra funds available so I can't just fix this with my checkbook!

 

I have removed my fair share of broken bolts and the only thing I can add is I firmly agree with the left handed drill bits!! These are golden when drilling out broken bolts because several times as I'm drilling, the bolt will start to turn and a few times they have actually spun right out!. "Marinating" it sure does help too.

 

Thanks for your input Rock304, I am going to look online for those drill bit this evening1 I just went out to the garage and gave the bolts a brew that I use as a gunsmith. 50-50 ATF and kerosene. I will alternate that with Kroil and PB Blaster! I hope between them all those 2 remaining bolts give up willingly so I only have to deal with the one broken on saturday.