Some ideas and questions on HGs problem - your feedback is much appreciated
a few months ago I bought a 2.0 GT 1990 Legacy (automatic transmission). I paid 500 NZ $ for it, and though the guy told me there was no problems with overheating I kinda new that was the case. Anyway I used to take this car to the mountains for snowboarding many times and one day the car overheated and I observed an external coolant loss from the bottom radiator hose. I could also see quite big bubbles coming out of the overflow bottle and then I knew immediately the HGs were bad so I took the thermostat out.
Since then car hasn't overheated anymore but undercooled. Now I want to put the thermostat back.
The question is:
1) What hole(s) size should I drill in the thermostat to make it pass just enough coolant (and all exhaust gases) so the engine does not overheat?
2) What do you think of using "liquid" gasket (in the hope it would "seal" the cracks in the HGs with the engine idling) and then re-tightening the head bolts?
3) Do you think that carbon dioxide which gets into the cooling system (when the HGs are leaking) would make the coolant acidic and therefore further deteriorate HGs (and other components)?
4) If you agree with 3), what would be the way to prevent the coolant from becoming acidic (e.g. using certain additives)?
5) And finally, is there any chance of replacing the HGs without taking out the engine?
Some of these ideas might sound a bit fancy but even the craziest ideas can be correct. Anyway I would be glad if this thread would cause an interesting and healthy discussion.
DOHC or SOHC? I did the HG on a 2001 Forester without pulling the engine. It was easy but a little time consuming...10 hours total over a two day period and about $400.I got good gaskets for around $300. I hear a DOHC is harder though. I wouldn't put any kind of quick fix gunk in there because I've been told by a few people that it can clog up the radiator and other parts. If I were you I would just bit the bullet and do the HG's.