Headgasket

Well, looks like SoDak has a blown headgasket. Someone, who shall remain nameless, drove the car for an unknown period of time "in the red" on the temperature gauge about a month ago. I thought it would be OK, but evidently it is not. Symptoms...

• When starting the car, coolant reservoir pressurizes even though the car is not warmed up.
• Loss of coolant with no coolant leaks
• Difficulty starting (it still starts at -5 F with no block heater)
• Faint odor of ethylene glycol (coolant) in the exhaust
• More white smoke out the tailpipe that usual
• RPM-dependent heater output (my guess is that combustion gases are entering the cooling system and preventing it from functioning normally)
• Periodic slight increases in coolant temperature (temp has always been rock-steady, again, gas pockets in the cooling system preventing proper cooling)

The definitive test for a blown head gasket is to test for hydrcarbons in the coolant reservoir using an exhause gas analyzer. Notice that coolant/oil mixing is nowhere on the list. Coolant oil mixing is NOT diagnostic of a blown headgasket as the oil cooler on this vehicle is liquid-cooled and is part of the oil filter assembly. The owner before the owner before me (a professional Volvo mechanic from Sweden no less) tore off the head to repair a "head gasket" and found that it was just fine and that the oil cooler had failed, a very unfortunate mistake...