I hoping that someone has experienced my problem, and can help me find a solution!
After conclusively determining that my internal oil thermostat was failing to open, I decided on a partial engine drop to provide access to replace the part. Finally, after having to remove "layers" of hoses, wire harnesses, aux air tube, etc. (as most of you well know), I finally had access to the thermostat. I was a little surprised at how easily the nuts came off, since the thermostat had never been changed (I'm the car's original owner) and I was anticipating corrosion.
Naturally, "Murphy" stepped in at this point. The thermostat is absolutely frozen in place. First, I used a Craftsman 90degree flat blade screwdriver to attempt prying the thermostat up. It wouldn't budge. By removing the coldstart fuel injector and associated parts from the airbox, I gained enough working room to admit a mini Stanley prybar (7/8" wide, 7" long). Although I'm able to get the blade under the thermostat lip, the prybar bends, but the thermostat doesn't give.
I suspect that the O-Ring has hardened and adhered to the engine. Gradual over-temperature increase over the years probably contributed to this. I don't think heat on the thermostat will help (and in any case, a torch would probably do more damage than good). Aside from trying to make a tool sort of like a bearing puller, I don't have any good ideas for freeing the thermostat. I've avoided using a lubricant such as WD-40 around the thermostat lip (possibly it would manage to get to the O-ring and loosen it), since I didn't want to make the thermostat lip slippery. Nevertheless, I'm going to try that next.
I'd greatly appreciate suggestions from members of this forum! At this point, completely removing the engine is not an option. If it comes to that, I'll have to reassemble everything and take the car to a shop.
Patrick Martin