Thermostat or Heater
 

Hi, I am new to the Bonneville Club. I have a 1989 LE with 136,000 miles on it. I have a question. The other day I noticed my temp gauge starting to rise while driving it would rise to about half way between the 100 and 260 then drop to about normal and then it happened again. I started to notice that as the temp gauge went up the heat blowing out of the heater would turn to cool air rather than warm or hot. I thought it was the thermostat first now I think there might be something blocking the heater.
let me know if anyone has any ideas on what could be done, want to keep the bonny runnin good and keepin me warm

thanks

ryan

Well, that does kinda sound like a plugged heater core. The heater core does play a part in keeping the engine cold, so that could cause a slight rise in engine temperature. I don't think it could be a thermostat, since you would still get more heat as the car got hotter.

When's the last time you had her flushed out and filled with fresh coolant? That may help, since it seems to be a problem that comes and goes (makes me think that it's just crud foating around that sometimes clogs the core, sometimes doesn't). If you go that route, you might want to disconnect the hoses from the heater core and try to flush it out in the reverse direction of the usual flow, just to make sure it flows okay.

Welcome to the club, by the way. :D