Thiis is realted to the other question I posted, but wanted to get your eyes on this so I could order a water pump if I need to ASAP. Issue: Car running hot.

Turning on the heater drops the temp 20 degrees in a minute or two.

I bought a thermostat and am prepared to flush the system. Just found something interesting:

Temp 220. Raise RPM to 4,000 and temp drops 10 or 15 degrees

Most of you are smarter about this than I am: does this tell us the water pump is bad?

I just didn't want to jump to that conclusion. OTOH could the higher rpm = more pressure on coolant flow so more gets past a partially opened thermostat?

Thank you for looking. Having had one of the defective water pumps I did learn that increased rpm = temp drop = bad pump, but as I typed this I just thought of the partial opened thermostat point above. If there is any answer please do let me know. The water pump in the car is about 2 yrs old.

Thanks,

John

 

I don't recall reading about vanes failing on pumps since the early AJ26 days, and I don't trust thermostats. My choice would be to replace the thermostat, but I have even found new ones that don't open completely.

 

Thanks mate. I'm off to replace it now. Fingers crossed! Will post results. John

 

You were right RJ. Replaced thermostat = all good now. Thanks.

John

 

Thermostat would been my first guess also. Having said that, I recently replaced my 2005 MY water pump, housing, thermostat, upper and lower hoses, and reservoir at 93,000 miles, just as part of preemptive maintenance.

I also replaced the idler pulley, tensioner assembly, and serpentine belt while everything else was out of the way.

The water pump vanes were cracked, the tower was brittle, the reservoir was beginning to leak, the hoses were soft (the upper was collapsing after shutdown, the thermostat was suspect (car had been running hot), and the idler pulley was wobbling.

I then took a 3,600 mile trip from Las Vegas, NV, to Oklahoma City and back (through El Paso, TX), and ran without issue in 95° to 111°F temps. Operating temps were 185° to 204° F on the road (pulling hills), and 204° to 214° F in stop-and-go traffic.

Preventative maintenance (and peace of mind) wins out over road-side repairs any day of the week!