Before I pull the engine...

[jdeight]

Because I never learn to leave well enough alone, while I was replacing my timing belt and water pump, I decided to replace the thermostat, too. For whatever reason, my 1980 does not have an external thermostat, so this replacement required removing the thermostat housing on the head. Having removed it, I discovered that at some point in the past, someone had snapped off one of the housing bolts inside the head. I did not notice the housing leaking before I removed it, but I also didn't drive it much. Now, because I cannot tighten one of the bolts, I cannot get the thermostat housing to seal to the head. I've tried various length bolts and several different silicone gasket making products. No matter what I try, coolant leaks from the housing and pools in the spark plug wells.

To fix this problem, I think I need to remove the head so I can remove the broken bolt and maybe re-thread if needed. I don't think I can accomplish this with the head in place and, once I screw it up, I'll need to be able to take the head to a shop to save my bacon.

I've never tackled any engine task quite as involved as removing a head, but I'm confident I could figure it out. I have a few questions, first:

What's the risk of postponing this repair? If I keep drying out the wells and refilling the coolant, am I running any risk by continuing to drive it like this for another coupla' hundred miles?

What else should I test before I take the head off? What other data should I have about the engine before I start dismantling it?

Does it make sense to limit myself to the head? If I'm going to go to all the trouble of pulling the head off, should I go ahead an pull the whole engine out and teach myself (with your and my local machinist's help) how to do a full-blown rebuild? Or can I get away with a head-only rebuild? I am pretty sure I need a new clutch, and maybe some tranny work, too (here's an example of where I haven't driven it enough to decide what I need). Maybe I should pull the engine and transmission all at once?

[131]

If you're not confident in removing the broken stud, pay someone to do it. A lot cheaper than removing the head for no good reason.

[klweimer]

Agree with 131, a good shop should be able to remove the broken bolt and replace it. Having a potential leak that big could leave you stranded with a blown head gasket or worse.
Kirk

[So Cal Mark]

one of several reasons I don't recommend swapping the external thermostat for the in-head version

[narfire]

Welded nut trick. Might be able to do it in situ as well.

[carl]

This is a classic example of mission creep. You start with a busted bolt and end up with a total engine and trans rebuild. As others have stated, get the busted bolt professionally removed, then drive the car to determine what if anything else needs to be looked at.

[jdeight]

Thanks for all the advice. Just to close out this thread: it ended up costing me $180 for my local guy to insert two helicoils. That and a buttload of silicone gasket fixed the leak.

After the fix, the car was misfiring. Of course it was the sparkplugs. No. 4 was the most corroded after sitting in coolant for a couple weeks.