I have a 1990 Daytona 2.2L. This car has had the headgasket replaced less than a year ago. Lately the temperature gage has been moving all the way up to hot, staying there for a minute or less then dropping back down into the normal range. Does anyone have any ideas as to what is causing this?

 

Slow reacting thermostat maybe. Sometime gauges do stuff like this where they spike and return to normal.

 

Has your coolant level changed? Certainly a faulty thermostat should be considered if the level has not changed. Or, replacing the temp sensor that screws into the head is easy and a cheap part to replace when trying to diagnose faulty gauges. If you are losing coolant, you might look for a weak hose with a pinhole opening. As the temperature rises, the hose balloons and releases some coolant, when the engine returns to normal op temp, the hose looks normal again sealing the hole. If this pinhole is over hot engine parts, you may not see a leak as it gets burned off. I found a similar pinhole by pulling off the road when the temp gauge was spiked and a very small amount was shooting out on to the exhaust manifold.

 

The coolant level is fine. In fact it is all new coolant.

 

could be the heater core, sometimes they get cloged, see if when it spikes you also don't have heat.

 

air bound will cause that condition also cracked cylinder head pull the spark plugs and look at them they will tell you if coolant is in cylinder