Whats everyone doing to make their cooling system better? 88/5.7/k1500 Under stress, long steep grades , low rps, my temp increases past 210. Cooing system is well maintained with regular coolant changes, a newish pump and radiator..Quickly cools down .

 

Is your radiator shroud complete? Have you tried cleaning the radiator fins externally? How old is the fan clutch (I assume not an electric fan). Towing something or hot w/o towing??

 

Not while towing. I live in flat land, California, on the coast. I rarely take it on any steep grades or steep hills at low speeds. Yesterday I took it up to loch Lomond to do some fishing. Speed limit is between 25 -35 mph. 577ft above sea level, maybe 10 miles at those slower speeds from sea level. Shroud is good. Fins clean. The fan clutch is 6 years old approximately, 15k on it. Radiator cap about the same age as the pump and radiator. Maybe its normal for a big truck to do that. I have owned this truck for 13 years so I know it pretty well.

 

Maybe your thermostat is not fully opening??

 

Possible but its only a few months old. Id say unlikely. And, I would think if it were Id have a cooling issue during regular driving. I dont. Back in the day on my older, like 1950s era Chevys. Id be able to put a spacer behind the fan to move it slightly closer to the radiator. On these pumps the bolts are pressed into the pump and they arent long enough for a spacer.

 

how many miles on that water pump?

 

Put in 5 years ago. 10,000

 

This sounds like normal operation. Lower RPM = slower coolant flow through the system = more time for coolant in the heads to heat up. The ECT is located almost right next to the thermostat - i.e. where the coolant is hottest right before it enters the radiator.

However if this is a recent issue, first verify the ECT sensor and gauge are functioning correctly. At key on, there should be +/- 5 volts on the yellow wire at the sensor and 0.1 volts or less on the black wire.

Unplugging the sensor should cause the gauge to read cold regardless of actual engine temperature.

The ECT sensor should read lower resistance at high temperatures and higher resistance at lower temperatures. Approximate range is 3400 ohms @ 70*F to 185 ohms at 210*F.

If the sensor and gauge prove functional, try downshifting to increase the engine speed or turning the heater on to provide additional cooling to the engine via the heater core and observe the effects. If engine temperature remains high, I’d recommend testing for a head gasket leak.

 

Thanks. Because I generally drive at highway or rural, city driving I didn't know if it might be expected. I understand the logic of low speed, high rps create more heat. I did put on the heat and it did drop the temp. Im certain that the head gaskets are fine. The state of California requires us to have smog testing every 2 years and I just went through that. If there was a problem with head gaskets it would have been found during the smog test process. I would expect that the cooling system on this truck should be able to handle a brief period of this kind of driving. Thanks again