I have a ’92 Toyota Pickup with 200,000 miles on it. Today when I started it up (the engine was cold) it began idling around 3000 rpms which is faster than normal. I drove it 1 mile, got gas then drove another 2 blocks before it finally died down. At that point I noticed that the engine temperature was just below the red area (hot)….but the heater/defroster was still blowing cold air. The engine temp didn’t cool off for another ½ mile or so and that’s when the heater finally started blowing warm air. What could be the cause of this sudden “erratic” behavior and how can I fix it?[

You might have a bad coolant temp sensor which is why the vehicle is idling so high.

You might have a bad coolant temp sensor which is why the vehicle is idling so high.


Would that cause it to overheat then when the idle settles down it cools off to normal?

I'm not 100% positive on that; I would have a computer diagnostic done to determine what exactly the problem is. You might even have a vacuum leak which is causing the high idle. A bad thermostat could also be causing the overheating.