My 94 amigo 2.6l will run for a while at normal temp., but every once in a while the gauge will slowly rise to a quarter from H and sit there for a little bit then drop back to normal.
Any ideas about possible problems
thanks

Air pocket in the system maybe? My thought is that when the gauge does that, the air pocket has shifted to where the sensor is and is causing the sensor to "heat up" because it's not being cooled by the coolant. Might think about burping the system and seeing if you get any air out.

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

An air pocket generally gets trapped in the intake manifold and stays there giving you a false "cool" reading 'cause the engine temp probe will be sitting high and dry.

Check the tension/condition of your alternator belt. It drives the water pump too. I had an oddball situation when the bolt that holds the tensioning bracket broke so the alternator just sort of bounced on the belt. When I drove there was enough air through the radiator to cool it down, but at idle it would overheat. It could be the water pump too but if it's not leaking and the shaft isn't wobbly it's probably ok.

Could also be a sticking thermostat I guess...

I had a thermo in mine that would go to about 3/4 scale, then "bam!" within seconds, down to normal. When I changed it out, I could see the shiny spot where it was sticking. Dropping it in boiling water proved it.
(and BTW, that's probly the main reason my head gasket "went away")

also could be from a lack of coolant... I had a gmc jimmy once overheat while driving down the highway because it was way to low.