Coolant Temps Bouncing all over
 

Since a recent spell of hot weather I have had issues with my coolant temps bouncing all over. Mostly in the HOT range. Mostly when idle or in heavy traffic.

A few weeks ago the fan would sound like a turbo-prop ready to take-off for several minutes after the engine was shut off.

Now, the fan seems to shut down within seconds of the engine being turned off.

I have not been able to find any threads on a control module for the 2.2 LS.

Does anyone know a part number for this or have a fix in mind? I can run in the 200-205 range all day the start creeping up to 212 then even into the 230s.

Usually, the temp will start dropping when it hits 220 but in traffic it just keeps climbing.

Let me know what ideas you have or threads on the 2.2 I see loads for the SS.

Thanks

Have you changed the coolant?

Mine does that too when it’s very hot outside, the rest of the time it stays very cool. I think this is because when I mixed the coolant I did not have enough water to make it 50/50.

Racecars use straight water to keep there engines cool, a more water mix will also keep it cooler.

I would just change the coolant if you haven’t already with the appropriate 50/50 premixed solution.

What year?
How many miles?
And have to checked the coolant level?

2009 LS with 276XXX miles. Ye and it is full in the reservoir and under the pressure cap.

I may try that and see how it works.

OEM 2009 coolant and thermostat?
Dexcool needs to be changed only has a 5 year life.
Change the thermostat while you are changing the Dexcool.

Check RockAuto for the fan assembly, easy to change out.


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No module on LS/LT.

The fan runs after shut off only when the coolant temp is over 240F (overheating).

Does the fan come on at about 219F?

Might be the pump.

Yes Don. Once I hit 219 while driving the temp starts dropping like a rock until it gets below 200 (usually 198) then it will start climbing again if I am not moving.

You may have the wrong t-stat, it should stay on until ~180F. Some misguided souls think 190F t-stats are better than 180F t-stats; some people have had GM dealers force 190F on them.

But, it should not routinely get that high while moving. Should stay ~190F.

Could be the pump or clogged radiator. I am leaning toward bad pump.

What color is the antifreeze?
Does the coolant look rusty?