Why is my Deville overheating?
05 deville overheating. Compression checks good
at 138 to 150. Changed thermostat. Purge line
seems ok with a steady trickle of coolant back to
the reservoir. Both fans are running. Heater blows
out hot air until temperature indicator goes one or
two bars to the hot side and something happens
and starts blowing cold. I'm completely stymied.
Any help would be much appreciated.