Expert: Roger J.M. Warrington - 11/9/2006

Question
Thanks for your help, I took off both of the hoses from the heater core and flushed them out with a garden hose, my car does not have a heater switch/valve. The heat has definitely gotten hotter in the car, but the temperature gauge still drops out of the operating range at highway speeds, any ideas as to why that would be happening?

Thanks in advance.

Kelly
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The text above is a follow-up to ...

-----Question-----
Three months ago had head gasket replaced, radiator flushed and filled and new thermo put in, at that point it was still warm outside and they could only get it to run at a normal temp without a thermostat. It is now colder here and I put a thermostat back in it and now I have the following problems. When car is started in the AM, car heat works, when you put the car in gear and drive, temp goes down and heater blows out cold air. When you park the car and turn heater off, leaving car run, heat goes back up, and has gotten always to the top end of the operating range. Once you get moving or rev it up the temp comes back down. One other note one of the hoses going to the heater core is hot and the other is pretty much cold. The hose on the radiator side of the thermostat also is cold. To me it is like the fluid is not circulating like it should. Any info is greatly appreciated.

-----Answer-----
Kelly;
OK easy- if you have a heater by pass switch on one of the heater hoses  , than it is bad,  or the heater core but I bet its the by pass switch.  or in line with the not so hot hose ok

Answer
kelly;
hi I wonder if the sending unit for the gauge is bad. also how are the fans working. I wonder if the thermastat is bad  or defective. that will also let one heater hose be warm and the other hot.once it is warm it should stay that way till you turn it off.