It never hurts to replace the thermostat. They are cheap. However, I don't feel that is the problem with not getting heat until 3K RPM's. Usually, the coolant level is low, the heater core is partially plugged. I have a question. With the engine at normal operating temp, running and the heater on high, do both heater core hoses get hot? Let me know. If the T-stat and flush doesn't help, my next concern (and I hate to say it) is a head gasket issue.
Let me know what you find.
Thursday, December 9th, 2010 AT 12:16 AM