"Gene Wagenbreth" <genewxxx@isi-OS4> wrote in message
news:hcskr2$4ak@venera.isi.edu...
>I doubt its the head gasket. It never gets too hot. Most of the time it
> runs fine and doesnt get hot. Why would turning on the heater make the
> temperature go down immediately if it were headgasket.
>
> Thermostat sounds interesting. Does the heater somehow bypass the the
> thermostat ? How difficult is it to replace the thermostat ? How much
> should it cost to have someone do it (ballpark) ?


The heater doesn't bypass but redirects heat. Those coolant lines go
through the heater core. With the heat on, a fan blows across it sending the
heat into the cabin.

For how to change it...
http://wiki.answers.com/Q/How_do_you...onda_Accord_LX