Try the heater core, it could be clogged, it sits inbetween the bottom of the driving council. They look like mini radiators, plus if it is this then your vehicle could overheat and warp the block, which is not good.
This would explaine the fluctuation in heat gauge.
Cheap fix. Buy a radiator flush kit they are like $6 at a parts store, and get new antifreeze.
You drain the radiator from the bleeder at the bottom, it usually looks like a wingnut.
Then drain the fluid out and dispose of appropriately.
After it dies down you will pour water flushing the system of the radiator and engine. Flush till it is only water coming out(close drain). Run engine for 5 mins. The drain and flush again. Now add flush cleaner and refill system (shut the drain). Run the engine for recommended amount usually 15 mins. Then drain adn flush till clear. Refill the system with antifreeze.
This should help. If not change the heater core. THen I would be out of regular ideas.
Tuesday, November 14th, 2006 AT 2:28 PM