Car overheats at idle, but fine at speed, also looses coolant but can't find leaks.. To start investigation, started from cold. Car reached temp and kept going, fans never came on and the coolant overflowed from the expansion tank. So the thermostat must have never opened. The thermostat housing seems to be in an impossible location to reach, what do I have to remove to get at it, and does this sound like the right diagnosis so far? Also the manual shows three bleed screws, the two on the crossover pipe are obvious, can't locate the third one, again looks like an impossible location to get at. Thanks for any help.