Overheating 08 Tahoe when driving slow

[AkaTahoe]

Hey guys I have a 2008 Chevy Tahoe with the 5.3 LS and 252k miles with a rebuilt engine.

Recently it has developed an overheating problem but only when going slow(35 and under) then when I speed up it instantly goes back down. I don’t really have any more information on this issue. I do have an engine light on but last time I checked that it was for something different. Im going to check the codes again later to see if there is anything.
Has anyone had this problem before and what could it be?

 

[mikez71]

Radiator fans working?

 

[97YukonNZ]

Hey guys I have a 2008 Chevy Tahoe with the 5.3 LS and 252k miles with a rebuilt engine.

Recently it has developed an overheating problem but only when going slow(35 and under) then when I speed up it instantly goes back down. I don’t really have any more information on this issue. Im going to check the engine codes later to see if there is anything.
Has anyone had this problem before and what could it be?

Hey there
Welcome to the forum from New Zealand
Im guessing that your model runs an electric fan on the radiator for cooling.
If so you may have an electrical fault.

Or if you are running a manual fan it may not be clutching correctly resulting in overheat at slow speed and when you are traveling at speed the vehicle is catching adequate air to cool.

 

[AkaTahoe]

Radiator fans working?

They were when this problem started a few weeks ago and have been but today when I drove it I couldn’t really tell if they were on. I had my music on and was too panicked to think about turning it down to listen for them

 

[AkaTahoe]

Hey there
Welcome to the forum from New Zealand
Im guessing that your model runs an electric fan on the radiator for cooling.
If so you may have an electrical fault.

Or if you are running a manual fan it may not be clutching correctly resulting in overheat at slow speed and when you are traveling at speed the vehicle is catching adequate air to cool.

I do have electric fans. Should I check the fuses for that then?

 

[97YukonNZ]

I do have electric fans. Should I check the fuses for that then?

Yes for sure. Check out the easy fix scenarios 1st. Could be an easy solution.
Cheers

 

[petethepug]

Check level of coolant in reservoir. If low or empty your sensor in the tank is bad. Buy a new tank and refill.

Open hood, crack beer, watch motor to see if overheats and/or fans come on.

 

[Marky Dissod]

Do you remember the last time you addressed the fuses & relays for your electrical fans?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[swathdiver]

Hey guys I have a 2008 Chevy Tahoe with the 5.3 LS and 252k miles with a rebuilt engine.

Recently it has developed an overheating problem but only when going slow(35 and under) then when I speed up it instantly goes back down. I don’t really have any more information on this issue. I do have an engine light on but last time I checked that it was for something different. Im going to check the codes again later to see if there is anything.
Has anyone had this problem before and what could it be?

There are 3 relays that run both fans on the Low or High settings. Make sure they are all working and the fans. If you have the K5L RPO code on your glovebox door, your truck has 700 watt cooling fans. Otherwise, it has 500 watt fans.

 

[Doubeleive]

Hey guys I have a 2008 Chevy Tahoe with the 5.3 LS and 252k miles with a rebuilt engine.

Recently it has developed an overheating problem but only when going slow(35 and under) then when I speed up it instantly goes back down. I don’t really have any more information on this issue. I do have an engine light on but last time I checked that it was for something different. Im going to check the codes again later to see if there is anything.
Has anyone had this problem before and what could it be?

check the electric fan harness & the motor plug side also, at one point there was a recall because the harness would melt. the fix was to replace the harness end with slightly thicker wiring. this is a example of what to look for but sometimes the wires melt behind the harness plug

 

[petethepug]

So much awesomeness. Picture says 1000 words. Cajun style harness connectors.

 

[petethepug]

Well, what are the results of the crack the beer test?

 

[danrduc]

Fans may not be going on high speed mode, relay not grounding for high speed. I had that happen recently in the summer.