97 Winstar overheats while idling

[ramintier]

I have a 97 Windstar that is running rough when idling and overheats. Any ideas?

[phil-l]

Well...

For rough idling, the first Windstar response is always "clean or replace the Idle Air Control (IAC) valve)". This is easy to do.

Regarding overheating: What symptoms of overheating are you seeing? Just the temperature gauge, or are there other signs? What does the temperature gauge indicate during normal driving? Has the engine cooling system been serviced regularly?

[wiswind]

Are you "using" coolant?
If so, any signs of leakage?....like around hose clamps, etc? (look for cheap before expensive).
Air in system (coolant leaks out....air can also be drawn in at the same location) will cause overheating.
Not using coolant....then don't worry about those possible leaks.

Thermostat original?
If you replace it....get the correct recommended temperature.....don't go with a cooler temperature as the computer controls will not like that.

Rough idle causing the CEL (Check Engine Light) to come on?
If so, you can get the code(s) read for free at many auto part stores (get the actual numeric code)
If not.....some fuel system cleaner......Chevron Techron ( last I looked, took 2 bottles to treat 20 gallons), Redline Complete Fuel System Cleaner.
Both of these are detergent based....
For stronger....solvent based, Berryman's B-12 Chemtool.
We should be switching over to the summer blend of gasoline now or soon....and sometimes problems crop up with the gasoline when they make the switch between blends......which makes a run of the cleaner come to mind.


It is possible for the impellers of the water pump to wear down (junk in coolant, even cavitation with air) and cause the pump to move less water.....which would show up at idle....
Don't know if the Windstar is prone to this or not....but some vehicles are.
Would be more typical of a neglected cooling system (like if you still have the original coolant in there).

Also.....do the radiator fans run with the A/C on at idle?.....if not.....the radiator fan low speed dropping resistor could be defective, which would cause no low speed fan operation......which would cause a higher temperature swing when you are sitting still.....as the high speed fans kick in at a higher temperature.
Low speed kicks in at a moderate temperature, and then the high speed kicks in at a high temperature.
I have pictures posted covering the radiator fan low speed dropping resistor.