Please note, this may be a captain obvious, but I'll put it out there due to the varying levels of experience 240 brick owners have. The heating system was working beautifully all week, engine temp was dead center gauge (comp board is eliminated). Then all of a sudden, when stopped at a light, the heat started blowing cold, as soon as I started driving, the heat came right back. Hmmm, initially I wrote this off as another dead/dieing heater valve.

Tonight while trying to resolve another dang accessory bushing failure (volvo factory parts) after 36K miles, I climbed under the car and found a small drip of coolant coming off the front of the engine. I checked the coolant resevoir and it was empty... bad Advance Autoparts waterpump after 36K miles. I pulled the upper rad hose loose at the radiator and found that the coolant level was just below the upper hose opening in the radiator (almost dangerously low).

So, if your heater spontaneously goes cold while idling at a light, your coolant may be getting low, perhaps not low enough to damage the engine, but if ignored, an overheat will occur!

My solution for correcting this issue will be a HEPU water pump install as 36K miles is simply not an acceptable lifespan for a water pump, heck even the Conti belts look new!

jorrell
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92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!