higher engine temp and higher idle when warm

[sunnyjimus]

the Engine in my 97 explorer is idling higher when it warms up & engine is overheating a little bit when under
a load (high speed or steep uphill grade) it does not overheat at low speed or idle. Can anyone please help me as I am good at parts replacement and not as good at trouble shooting? Thank You

 

[MrShorty]

When was the last time you drained/flushed the cooling system? Is the radiator clean so that air can pass through the fins? Those are also the same symptoms I got when my fan clutch got old and tired.
I'd start with a coolant flush if it's been a while since that's been done, since that's a maintenance item. While you're doing that, observe how the radiator drains. If it drains quickly with a steady stream, then the radiator probably isn't clogged. If it trickles out, then the radiator could be clogged. Maybe have a flow check done on it at a radiator shop.

 

[TPLYNCH]

May want to replace the thermostat too. BTW, the engine will automatically idle higher if the computer senses the engine is running hot or approaching overheating.....

 

[Alec]

Don't forget the radiator cap too.

 

[sunnyjimus]

Thank you. It was the thermostat.