We're having problems with our Isuzu Amigo's heat. My husband wants to change the thermostat to see if that has any impact, but it appears to be buried in a hard-to-reach location. He's worried about having additional problems with the engine after taking it all apart and putting it back together again. We have a repair manual and that has been pretty much useless. Anyone know a good reference book or can give instructions to save us a costly trip to a dealership to have this done?