I have an '89 Toyota Cressida and the temp guage has started indicating a hot condition. It'll run way up to hot and then dip. Sometimes does it at speed but usually more at low speed/idle. In that respect it acts like you'd normally expect in an overheat situation, however I put in a brand new radiator less than a month ago. When it started doing this I replaced the thermostat, still does it. The engine has about 30k miles on a complete rebuild. Water pump seems tight, belts are snug. If I keep the engine RPMs at around 2500 when standing still, it's usually okay.
The belts are snug, but would a fan clutch cause this kind of condition? How can you tell if the fan clutch is bad? There seems to be a fair amount of air moved at a low speed, but I notice I don't feel particularly more blow back from the fan when I rev the engine.
Other than a bad temp sensor or the guage itself, if the car is actually overheating, what else could cause it?
Thanks for all input