Offroad Trailblazers and Envoys

Overheating problem

BDS, ReadyLift, Smaxx... You name it, we know about it here.

by cpyonker » Thu Jun 14, 2018 11:26 pm

Since I finally got my license and started driving places I’m finding even more problems!
I have difficulty with overheating in stop and go traffic and long stretches above 60mpg in hills.
But that’s it and other than that it is running below 210. I just doesn’t keep temperature anymore which may be part of my mpg problem.


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by Flyingfischer5 » Thu Jun 14, 2018 11:54 pm

Bingo! That is your mpg problem.

I would say your fan clutch is going out. Very common problem on these rigs.
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by cpyonker » Fri Jun 15, 2018 7:37 am

How does the temperature affect mpg? Just wondering.


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by Flyingfischer5 » Fri Jun 15, 2018 7:47 pm

cpyonker wrote:How does the temperature affect mpg? Just wondering.


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I don't know the exact science of the fan clutch but the clutch changes the speed of the fan. If it's going out it can't get up to a high enough speed to help with cooling. It also effects mpgs because the clutch doesn't disengage and re-engage like it's suppose to so it robs power if it's not working right.

If I was you I'd jump over to GMTNation.com or Trailvoy.com and see if you can find any threads that help explain the problem.

Hope this helps

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by djthumper » Sat Jun 16, 2018 6:17 pm

Replace your thermostat and possibly temp sensor first. You should be running at 210 not too much below.
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by Trail X » Thu Jun 21, 2018 1:27 pm

Overheating sometimes starts in the transmission too. My system will run ok until the transmission starts to overheat, then the whole system starts to rise in temp. Does your trans ever lock up in 4th gear? If not, it's a ton of extra heat that gets generated. Even if it does lock up, the pwm valve in these lockup clutch circuits tend to still create a lot of heat. My fix was a combination shift kit and trans cooler. City driving overheating is often different though... Might be two unrelated things.
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by Trail X » Thu Jun 21, 2018 1:33 pm

cpyonker wrote:How does the temperature affect mpg? Just wondering.


Higher engine temps doesn't generally hurt gas mileage. It generally helps, surprisingly. If an engine over-cool however, that's when you will see poor gas mileage because the colder cylinder walls will pull more heat (energy) out the combustion, resulting in less energy going to propelling you forward.
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