My car's internal heating fails occasionally, randomly. Whenever the heating fails, after some time the engine overheats and the hot coolant backfires into the reservoir. The two factors -failure of cabin heat & engine overheating - are linked. It always happens together. The day the internal heater works well, the engine never heats up. I checked the hoses. When a problem arise, the hose going to the dash board is hot, while the one returning from the dash board is cool. The hose going to the top of the radiator is hot and the one at the radiator bottom is cool. I changed the thermostat. No improvement. ( Is it that by sheer coincidence the second thermostat also is bad ?). I will highly appreciate your guidance. Two mechanics sais that they do not understand the problem.
Jan 18, 2010 at 9:39 AM