Hey all, I took the car out today for a ride. 47* and sunny. coolant temp always reads 198 -199 even last week when it was 87* out and it read 198*. Today I dropped wife at strip mall and waited with enginge running and it got to 210* in about threre or four minutes. Took off for a ride to see some dallas mansions and during the slow cruise it got to 210* it would cool off some when I would drive a bit faster. But it went between 210* and as low a 187* Never runs that low at full warm up. Went that low twice. this is running betwen 40 and 55mph. Got home and let it idle in the garage it went up to 226 then down to 214 - did it twice. Any clues why I now have higher temps?
thanks for your help.
Barry

 

I know it's normal to get that high, but that low I have no idea. Especially in this weather we have today. Hope someone can chime in.

-Alex

 

thanks Alex

 

Did you have the AC On or in Auto position?

 

The stock thermostat opens at 186. With an ambient temp of 47 its possible to get down that low when driving at moderate highway speeds. In traffic or in your garage with no air moving through the radiator the temp will go to the normal operating temps defined by fan the programming. Normal fan operating temps:

Low Speed Cooling Fans
The low speed cooling fans are controlled by the PCM based on the following inputs:

Low Speed Cooling Fans
The low speed cooling fans are controlled by the PCM based on the following inputs:

• The A/C system
• The Engine Coolant Temperature (ECT) sensor
• The Vehicle Speed Sensor (VSS).

The PCM will turn the low speed cooling fans ON when any of the following conditions exist at idle:

• Certain PCM Diagnostic Trouble Codes (DTCs) are set.
• ECT above 104°C (219°F) will enable low speed fans.
• A/C head pressure above 219 psi.

Once the low speed fans are turned ON by Engine Coolant Temperature, the PCM will turn the fans OFF when that temperature has dropped about 6°C (11°F). If the low speed cooling fans are turned ON by high A/C head pressure, the PCM will turn the fans OFF when the pressure has dropped to 150 psi. The minimum ON time for the low speed cooling fans is 50 seconds.

When engine speed is above 3500 RPM for 12 seconds and the engine oil temperature is above 127°C (261°F), the low speed cooling fans will be turned ON.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=211397&evc=sm&pubid= 134&cellId=32529&mspsdsubkey=831#ss2-211397">High Speed Cooling Fans

The High Speed Cooling Fans are controlled by the PCM based on the following inputs:

• The A/C system
• The Engine Coolant Temperature (ECT) sensor
• The Vehicle Speed Sensor (VSS).

The PCM will enable high speed cooling for both fans when any of the following conditions exist:

• Certain PCM Diagnostic Trouble Codes (DTCs) set.
• ECT above 109°C (228°F).
• A/C head pressure above 225 psi.

Once the high speed cooling fans are turned ON by the Engine coolant temperature, the PCM will turn the fans OFF when that temperature has dropped about 6°C (11°F). If the high speed cooling fans are turned ON by high A/C head pressure, the PCM will turn the fans OFF when the pressure has dropped to 180 psi. The minimum ON time for the high speed cooling fans is 26 seconds.

Bill

 

Pretty much the same as C4 LT1. Thanks.

 

off

 

thanks Bill that is a lot of great info but until today I ran always at 198 and up to a max 199 sitting at a signal.
Barry

 

HI there:
I would be checking for debris that the radiator may have picked up.Is your coolant cap tight? Any seepage around the water pump? How old is the coolant? Clean looking & on the full mark?My stock 01 will run at 187 on cold days in highway driving.
robsc501

 

.

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Look under car at top of radiator for debris sucked under there.
.

 

sounds like your thermostat is sticking on you.this will cause high and low temps. ed k

 

With the AC off that was perfectly normal. Notice in Bill's data what temps the fan's come on, notice that AC head pressure turns on the fan. So with AC in operating mode, for heat or cool, the fan's will operate to keep the engine at that 190s range.
Without the AC it gets fairly warm before the fan comes on.

 

I understand the data pretty well but I don't know why the drastic change in 1 day of driving. It has never gone above 199 since I purchsed it late last year. Always at 198-199 on weather from 30* to 87*.
I had none of these fluctuating numbers yesterday. Thanks

 

Don't know... could be just a gremlin. If it is back normal now just keep an eye on it from time to time.

I just run them in auto mode all the time, whether I need heat or air and let it figure it out. That way I'm sure the fan's are operating.

Could be nothing...

 

It is not unusual for ours to run up to 235. I always comes down as soon as the fans take over or I get back underway. Due to the fans running in conjunction with the AC, it will actually run cooler (at least for a while) with the air ON.

Make sure you don't have debris, and that the DEXCOOL is up and good and with a good cap on the resevior.

 

Thanks - this is just a one day transition for me. It ran 198-199 max yesterday in the same kind of driving.

 

Kind of what I was thinking too. Would be an area to check out.

 

Last Friday, I fired up the compressor and blew out the radiator both ways. I couldn't believe the debree that came out. Did this 4-5 times then from the top. Car has 14,126 miles and hasn't been driven much in the last 9 months due to a broken ankle. Didn't think I drove it in dusty conditions, but it's a vacuum cleaner. Saturday I drove over a plastic bag at the shopping center and it was sucked up into the radiator. Temp went from 190 to 198 in no time. Reached under the car and pulled it out.
Try what I did and see if that helps.

Ken

 

Drove the car again today and had no problems I got home and idled in front of the garage for five minutes and never budged from 198* ???
Sounds like a sticky thermostat?

 

Hi jobear;
After reading more of your posts its acting like a sticking thermostat.
The gm p/n is 12571261 comes as a housing which includes the thermostat & o-ring. I bought mine from the dealer at wholesale $32.69 List was $44.05
robsc501