Overheating

I have a '94 Metro that keeps spiking the temp gauge once in a while. It also looses coolant about 1/4 of the radiator everytime it is drive. The overflow tank is apparently spewing out coolant (boiling over) as there is always some right underneath the overflow boil over hose. I think this must be the reason it is losing coolant as I am not finding any indications of coolant mixed in the oil or any steam pouring from the exhaust. I've replaced the thermostat and radiator cap as well as "burped" the cooling system. The fan does come on and in fact I removed the AC drive belt (so the compressor doesn't turn) and started to turn on the AC button in the car just to have all the fans (the AC fan included) blowing on the motor which helped a little. I also don't see any leaks in the raditor while the motor is running nor do I have any dampness in the carpet by the heater core. What could be the cause of the overheating? It also makes the infamous metro belt squeal and I was wondering if the belt could be slipping on the water pump drive pulley and making the coolant not flow properly hence overheating (this car had a strange charging problem before too that was traced back to the belt after an almost $200 alternator). Or maybe I have a restriction in the radiator? It started happening infrequently a while ago and I took it into an auto shop who told me they couldn't find anything wrong with it and the cooling system pressure checked fine. Maybe the water pump is going then? Thanks in advance.

What is the condition of your radiator? Is it the origional from when the car was new?

Yes, I believe so.

I had problems very close to yours on my '94 and found out I had a bad radiator.

I would say you have one of two problems. Radiator or water pump. I would start with the rad as it is the easiest to remove and go from there.

Also, check your oil to see if it's only oil in there. You could very well have a blown headgasket.

I've checked my oil and there is no coolant mixed in there. I think I may try the radiator first.

I had the same problem and my radiator was completely clogged.

Do not let your car overheat into the red. When it starts getting hot, shut 'er down. These engines love to warp, and when they do it usually requires machining the head AND the block, which means you're pulling and entirely disassembling the engine. Goodluck.

-MechanicMatt