2000ranger xlt 3.0 l v-6 auto tranny.
been having issues with temp gauge going to hot while stopped in traffic ,intersection. while driving without stopping there are no probs. did coolant flush and then installed a new thermostat but problem persist.burped the system and topped it of but no difference. installed new temp sending unit and still the same. i did notice that my heater air is luke warm at best. so im not getting good coolant flow through entire system. my question is, should i replace the water pump next. if not better then replace radiator. yes i ran the heater during flushing sequences and fresh refill. thanks for any thoughts on this thats got me stumped.

 

Did you flush the heater core? You can also reverse the hoses to run the coolant through the heater core the opposite direction without any problems.
The 3.0 has been known to have the water pump impeller corrode away. This would also cause the issue you are having if the impeller is partially worn (corroded) away. It will have "Some" water flow and when you are moving you have higher RPM and the added airflow from driving. But when stopped it will heat up do to loss of air flow and coolant flow,
How dirty was the system / radiator when you did the flush?

 

Your symptom is classic for failing Fan clutch or water pump impeller

Test the fan clutch first
When engine is cold, like after sitting overnight, open the hood and try to spin the fan, should be TIGHT, hard to spin, but will move
If not then clutch is bad

But test again after driving home from work or after 15-20 min drive, open hood, engine OFF, and try to spin fan again, when radiator is hot, should be hard to spin same as when Stone Cold
If it spins easily then clutch is bad

The fan is only used when driving slowly or stopped, it pulls air through radiator, when driving at speed there is enough air being pushed through radiator so fan is not really needed

If fan clutch tests OK
Impeller on the water pump may be worn down, it can get eaten away if coolant is not changed every few years, called Galvanic corrosion, it happen because coolant PH is to low
This causes low circulation at low RPMs, but better circulation at higher RPMs

 

system was extremely dirty and rusty.ive owned the truck almost a year, i dont think it was ever changed by previous owner. thanks rock for your input.

 

hey ron, thanks for your input.

 

Let us know what you find!