: Fan Clutch/Cooling Issue

08-04-11, 01:13 PM
Recently my car has been experiencing higher than normal coolant temperatures and I'm not exactly sure what is causing it. The temperature usually sits between 205 and 215, but when I get on the highway (usually on the entrance ramp) the temperature starts to spike. In a few minutes the temp maxes out the gauge (goes past 260) but less than thirty seconds later, it will read in the low 200's again. Whenever I stop to check the engine, while the gauge is scrolling "HI", there are no signs that anything is overheating.

The radiator and thermostat were put in last year, so the coolant isn't that old. I thought it might be the water pump, but I don't have any signs that the pump is bad (no leaks, no noise), and I can't see the temp dropping that fast with a bad pump. I pulled DTC's and didn't get any, so the computer hasn't registered that the engine overheated.

The only other thing I can think of is the radiator fan, and my manual doesn't give much information about it. With the engine still hot, I can spin the fan and get it to freewheel from one blade to the next. It seems loose to me, but the manual doesn't say how to test it when hot. The book says that with the engine cold, the fan should not freewheel any more than 5 turns, but that number seems somewhat relative. Does anyone know a more definitive way to test the clutch? I would also like to know how much of a pain it is to replace.

Any other ideas and suggestions would be welcomed.

08-04-11, 01:53 PM
Does the temperature continue to rise once you're moving more than ~30 MPH? If so, it has nothing to do with your cooling fan, as the airflow from driving will cool the radiator. You're assessment of the water pump is correct, if it's turning, not making noise, and not leaking, it's fine. Have you checked your coolant level?

08-04-11, 03:46 PM
It usually doesn't start increasing until I reach 50mph, and then it spikes. I checked and there isn't anything blocking the radiator and the coolant level is fine.

08-04-11, 04:33 PM
are your temp sensors good? were they replaced before?

08-04-11, 05:16 PM
I replaced to one when I installed the gauge. I'm not so sure about the one for the computer.

08-04-11, 06:37 PM
Clutch is cheap (i think like 45.00 for mine) and simple to replace. I started replacing mine but changed my mind, i just cleaned the bimetal coil and called it a day.

08-04-11, 09:13 PM
It usually doesn't start increasing until I reach 50mph, and then it spikes. I checked and there isn't anything blocking the radiator and the coolant level is fine.

At 50 MPH , your cooling fan serves no purpose. A bad clutch wouldn't cause an overheat problem at speed. From your description, the temp seems to rise and fall fairly quickly. To me, that indicates either air in the system (hear any gurgling?), a bad sensor or gauge., or possibly a slightly sticky thermostat?

08-04-11, 10:10 PM
The more I think about it, I'm thinking it is a bad gauge. Cyberdyne made the gauge and I called them to see if the gauge could misinterpret the reading from the sender. They said it was probably RFI or a bad ground screwing with the reading. I ordered a new one in June, because they are crap and the LCD display dies after two weeks (can't read the last digit), so hopefully when I get it, that will be the end of this issue.

In the meantime, I might cook me up a thermostat...

Rick James
09-07-11, 03:22 PM
It sounds like your fan clutch is fine. It wouldn't spin more than a rotation or two if it was going bad.

09-07-11, 03:26 PM
One thing that I love about Cadillac is that problems will mysteriously resolve themselves. I was getting ready to take the thermostat out, and the gauge stopped reading high and the temperatures have been fine since.