My friend's 1995 Eagle Talon ESi's heat shoots up when he is stopped at a light, stop sign, etc. What could be the reasons behind this? It heats up quickly, then goes back down in about 1 minute or so, and when he starts to drive. The heat coming from the heater is cool, however.
you antifreeze level is low and air is in the system
top up the rad and over flow jug then check for leaks dont check it hot let it run with rad cap off to bleed the air out as you top it up let it run till thermostat opens the upper rad hose will be hot when it opens then drive it later on recheck level's when cooled
I thought opening the rad cap when hot would make the fluid shoot up in the air
you might have air in it or the hose is bad or waterpunp if the water isn't moving when you look in the fill hole but most like it seem to be a bad thermostat