Bad Water Pump?

[Ken Cunningham]

Why does my Regal overheat at idle?

The radiator is one-year new, filled with distilled and RMI 25. The thermostat is a 160 and I monitor the temp with a vdo gauge.

Normally it will run below 160. Only at idle, I see the temp needle run way up near 250. Putting the car in N and gunning the engine usually helps reduce the temp. Turning on the heater also helps.

Is this a typical failure mode for a water pump? Does a pump get lazy at circulating water? In the past I have only replaced pumps when the bearing became loud or the pump seals leaked.

The heater control valve show some discoloration like it leaks, but I don't lose much coolant. Even after showing 250 on the gauge, I don't notice any boil over, so it may be that the gauge is screwy. But the symptoms are pretty consistent and I don't want to risk my engine.

 

[TurboDave]

Why does my Regal overheat at idle?

The radiator is one-year new, filled with distilled and RMI 25. The thermostat is a 160 and I monitor the temp with a vdo gauge.

Normally it will run below 160. Only at idle, I see the temp needle run way up near 250. Putting the car in N and gunning the engine usually helps reduce the temp. Turning on the heater also helps.

Is this a typical failure mode for a water pump? Does a pump get lazy at circulating water? In the past I have only replaced pumps when the bearing became loud or the pump seals leaked.

The heater control valve show some discoloration like it leaks, but I don't lose much coolant. Even after showing 250 on the gauge, I don't notice any boil over, so it may be that the gauge is screwy. But the symptoms are pretty consistent and I don't want to risk my engine.

When the engine is idling, does your coolant fan cycle on and off? If so, did this problem just crop up "out the blue", or was some work just completed?
Could be too much clearance in the water pump housing.

 

[Ken Cunningham]

When the engine is idling, does your coolant fan cycle on and off? QUOTE]

I'll have to check that one.

This did just arise out of the blue. Last year I had overheating probs when climbing hills, so I replaced the radiator. Now the problem only arises when I am at a traffic light, drive thru lane, parking lot, etc.

Could a defective fan (relay or other) cause a rapid and profound rise in idle temps?

 

[441120]

fans

The fan must work at idle, with the car not moving no air crosses the radiator core, no air movement no heat exchange. Water pump should be OK only replace when leaking/noisey.
Good luck it's getting hot out

 

[T-top87GN]

Why don't you get a scan tool on the car and verify your gauge is working?

 

[Ken Cunningham]

Why don't you get a scan tool on the car and verify your gauge is working?

Jeremy: Good call!! I didn't even think of that, and I keep a scan tool hooked up at all times. Temp is one thing I usually don't even pay attention to, but the ECM gets its water temp from a different place than my gauge so that will tell me a couple of things.

 

[Ken Cunningham]

Some updates:

My scan tool shows very similar readings as the vdo gauge. So the car really is overheating.

The fan is on and blowing like crazy, even as the temp soars to 240+.

Hard as it is for me to believe, putting it in neutral and goosing the throttle really does help bring the temps down.

Tomorrow I'll put in a new water pump and a new 160 deg thermostat. Refill with distilled and RMI 25.

I'll let you know what happens.

 

[Jerryl]

Some updates:
The fan is on and blowing like crazy, even as the temp soars to 240+.

Hard as it is for me to believe, putting it in neutral and goosing the throttle really does help bring the temps down.

Dumb question.
Is the belt slipping so the water pump does not turn sufficiently at idle?

 

[Ken Cunningham]

Jerryl: Not a dumb question. The belt is making some noise, probably from the tensioner. The water pump pulley seems to be turning OK, though.

 

[Ken Cunningham]

I'm Such A Dork!

Do-oh!

Turned out to be nothing more than a low water level in the radiator. For some reason, the overflow tank remained full, but the radiator level was low.

I already had the i/c out before I noticed, so I went ahead to R&R the water pump and thermostat. I'd been wanting to tighten my oil pressure sender anyway, and it's under the water pump/radiator hose.

BTW, the thermostat housing hold down bolt is REALLY hard to install unless you remove the 's' hose next to it.

It's all back together now and runs cool, even w/ the a/c on and it was a hot day yesterday. Thanks for all the input.