Run a compression test to see if overheating has damaged the engine. All cylinders should have somewhere near 100PSI compression, but whatever it is, all should have similar compression. If any are significantly different, you've probably warped the head resulting in a damaged headgasket. That's the most common problem that is caused by overheating. If you don't have one or more cylinders with low compression, just try a computer diagnostic scan to see what kind of diagnostic codes have been stored. If you don't have low compression, the computer should be able to tell you what's wrong. God luck.
overheating, or running too cold
Is you Geo Tracker overheating or the temperature is running almost hot then you need to change you thermostat
Replace it with the exact same temperature thermostat as the one you removed. Do not run the engine without a thermostat. The thermostat is required to keep the engine running at the optimum temperature that will give the best performance and mileage. If it is overheating running it without a thermostat is not the solution.
Check the heater core; either it or the lines running to it are clogged.
When 1990 Honda is running cooling fan does not come on but comes on when engine is off and I thermostat and temperature switch changed?"
Your thermostat is probably stuck open - quite common - had to have my thermostat changed for the same reason (Helpfull)
have you checked the fan
fan relay or thermostat
Could be a bad thermostat-not opening
have you checked ur thermoswitch or the relay Simply check if the fan units are running when the engine is hot. Easiest to do when the hood is up. Are you losing coolant from the expansion tank, this could be a sign of failed Head Gasket.
Get a Bigger Radiator
Most likely you have overheating, that's why the keeps running. You need to check the temperature control sensor and the thermostat.