Thermostat housing bolts broke

[sjantzi]

So when removing the thermostat both bolts broke off (about a 1/4 inch of the end). I have penetrating oil added now. Any advice on how to proceed would be appreciated.

Thanks

[Dave Neptune]

s, keep the penetrating oil going and "tap lightly" side to side in all directions. When you can see movement via the p-oil popping out you will know it is getting loose in the threads as there is no longer any strain on the threads other than the rust and or sealants.
Also lightly tap the stud downward too, once you have any movement it should be no problem to extract.

The housing should be held by studs not bolts.

Worse case you may have to R&R thye head to get the stud out.

Patience and lots of taps will usually work without destroying the threads.

Dave Neptune

[sjantzi]

s, keep the penetrating oil going and "tap lightly" side to side in all directions. When you can see movement via the p-oil popping out you will know it is getting loose in the threads as there is no longer any strain on the threads other than the rust and or sealants.
Also lightly tap the stud downward too, once you have any movement it should be no problem to extract.

The housing should be held by studs not bolts.

Worse case you may have to R&R thye head to get the stud out.

Patience and lots of taps will usually work without destroying the threads.

Dave Neptune

Thanks for the reply! The previous owner had replaced the thermostat in '92 (found the receipt) and used a spacer to get it to fit and used bolts.

I was planning on drilling and using easy out tool to try and extract. Is there any concern about shavings getting into the water jacket?

[Dave Neptune]

Before drilling try for the extraction. Damage to those threads is not good as they are also doing headbolt duty. You need to maintain good threads so the head will stay put.

The drilling is a last resort. Once the bolt broke the stress holding it in place was eliminated and only the friction in the threads remains.

Dave Neptune

[sjantzi]

Before drilling try for the extraction. Damage to those threads is not good as they are also doing headbolt duty. You need to maintain good threads so the head will stay put.

The drilling is a last resort. Once the bolt broke the stress holding it in place was eliminated and only the friction in the threads remains.

Dave Neptune

How would you attempt extraction without drilling first? All examples I've seen require drilling first

[Peter]

I was planning on drilling and using easy out tool to try and extract. Is there any concern about shavings getting into the water jacket?

Virtually every time I have tried to use an "easy out" tool it has broken off in the hole and made the problem much worse.

Peter

[sjantzi]

Virtually every time I have tried to use an "easy out" tool it has broken off in the hole and made the problem much worse.

Peter

Can you recommend an alternative?

[Peter]

I would follow Dave's procedure as outlined in post #2

Peter

[marthur]

I had the same thing happen. The number one tool is patience.

I had just enough bolt sticking out of the head to get vice grips or a very small pipe wrench on the thing (ended up using both). It took three hours and the program was a combination of heat, penetrating oil, tapping with a small hammer on the top of the bolt and on the vice grips and working it back and forth to get it out. Finally a big heave on the pipe wrench with a 18" piece of pipe on the handle did the trick.

Everyone has their go-to trick to start with, mine is some combination of heat and impact. I have come to LOVE my 18v impact wrench, but on the Catalina 27 we recently sold there wasn't room to use it very often.

I will also second the easy-out observation. My experience with easy-outs is very mixed and I fear having to grind the hardened steel out of the hole so I use them only in special cases. The problem (as I see it) is the easy out tends to expand the bolt / stud making it harder to remove.

Good luck!

[Nahart]

I've had luck with a reverse bit from Harbor freight. It drills in reverse and encourages unscrewing. After the normal treatment of soaking, tapping, etc., I would drill in reverse and more often than not the bolt would unscrew way before the bit ate up the bolt.