Overheating while towing

[rcchemtech]

I have an 08 Silverado 5.3 While towing the temp will rise to 230 or so when outside temp is above 75. When this happens I can turn the heat wide open and temp lowers to 210. I have replaced water pump, radiator, thermostat, and temp sending unit. I still see temp rising while towing, Does anybody have an suggestions?

[rcchemtech]

E

 

Blown head gasket or cracked block/heads.

Would I only see that while towing, it has never overheated while not towing I am not losing coolant or oil!

[music]

More info. Tow package? Aux transmission cooler? Trailer weight? Steep grade in 2nd gear, or flat land?

[Gun Designer]

Either run a pressure test on the cooling system or have it done. How about the transmission temp? Maybe the tranny is heating up and that heat is pushing up the water temp when towing, but runs normal temps when not towing.

[brucelimerick]

Do you have a separate transmission cooler or is it hooked into your rad?

Automatic transmissions slip, normally about 3%, this generates heat. More slip, more heat.

You might also check your fan. My year has a viscus clutch, the hotter is gets the more it hooks up and draws more air through the rad. At highway speeds you shouldn't need a fan. Check the fan cold, you should be able to spin it. Check it hot, it should be difficult to spin or not spin.

[brucelimerick]

If it is the tranny generating the heat you probably have burnt the fluid. Pull the tranny dipstick and smell the oil. If it is burnt it will be a brown red instead of bright red and will smell burnt. It is a pretty distinctive smell.

[txab]

Do you have a separate transmission cooler or is it hooked into your rad?

Automatic transmissions slip, normally about 3%, this generates heat. More slip, more heat.

You might also check your fan. My year has a viscus clutch, the hotter is gets the more it hooks up and draws more air through the rad. At highway speeds you shouldn't need a fan. Check the fan cold, you should be able to spin it. Check it hot, it should be difficult to spin or not spin.

 

2008 5.3 has E-fans

 

Remember your coolant/water mix should be good to about 265*. I'm not saying that's what you want to run at

 

The ECM will also produce a message in the DIC and force you into reduced power if you really overheat

 

As mentioned have the system pressure tested including the cap. If all checks out, I'd look at a larger cooling capacity radiator and replacing the aux trans cooler if equipped with a larger cooling capacity unit.

 

More info on your towing situation would be good. Weight, driving terrain, gear selection etc

 

Also would double check the actual temperature, the gauge on the dash could be off

[brucelimerick]

And what are E-fans?

[txab]

Electric fans

[toolsinbox]

And what are E-fans?

electric fan

[brucelimerick]

Ah, what I had in my Rabbit 30 years ago. GM is catching up. lol. I would assume GM also has a fan control switch mounted in the rad, that should be checked too. The one on my Rabbit would run after the engine was shut off if it was hot. GM?

[white1500]

Are you going up hill? Do you have a tranny oil cooler? Do you notice anything strange in your engine oil?

 

And you might have a blocked radiator, that happened to me last summer and it gave me a ton of problems! I ended up replacing almost every part of the cooling system along with a 34" inch rad, up from 28. No issues in heavy traffic in up to 120 degree weather, I'm crossing my fingers and knkcking on wood for a problem free summer....

[mike94silverado]

when my dash reads 210 the ecu is reading 192 per my edge insight... just a thought....

[Silveradooh9]

What temperature thermostat did you replace the old one with?

[rcchemtech]

Thanks for all the help! I have done a pressure test on the rad, changed the transmission fluid and added an extra trans cooler. I had the same thought on the trans fluid placing extra load on the cooling system so I bypassed the rad trans cooler. I am going to hookup the camper for a test drive later this week to see if the problem had been resolved. The outside air temp has dropped so pulling now tells me nothing. The last idea I have is could the ranch hand bumper be blocking enough air to cause higher temps?

Thermostat 185.