Hello,
I am having some problems with my car. I recently replaced my monovalve and during what has so far been a mild winter have had heat in the car and been fine. This weekend it was frigid cold, and I took a long trip to Maine. On the way there, my car barely heated above 60 degrees C according to my temperature gauge, and the front of my radiator is ice cold. I haven't had any problems with overheating throughout the summer. But now if I leave my car running the temperature gauge doesn't heat up, however I am able to get some hot air running in my car, and as long as I leave the heat running afterwards while driving, I can maintain warm heat coming into the car. If I shut off the heat while driving and turn it back on, then it blows cold air.
I am wondering, do I need to replace the Thermostat or is this a water pump issue? I opened the resevoir cap slightly after driving for a few hours, and the coolant is very hot and steamy, so some circulation is happening, and since I can get heat if I run my car for a bit while sitting in a parking lot.