Good evening everyone, I have a 04 Chevy 2500HD 4x4 extended cab with the gas 6.0 engine. I've only had the truck for about a year now. When I got it the a/c was not working but upon fixing it, I discovered that when I'm towing my travel trailer and run the a/c, the temperature hand runs all the way up to 258 right at the run hot red range. If I don't use the a/c, it runs cooler. Here is what I have done so far: -1 I have put a bigger three coil radiator on it. -2 I put a heavy duty towing fan clutch on it roughly 7 months ago. -3 I just put a new radiator fan shroud on it this week. (upper and lower) -4 I have also replaced the thermostat. -5 Replace the cap on the overflow reservoir.

Please help if anyone has had this issue. The only reason I purchased this truck was to tow my travel trailer and it's not suiting the purpose if it's running hot on me. When the temperature hand runs up like it does, if I stop the vehicle and switch it off, antifreeze actually boils out of the over flow reservoir. Anything that you can do to assist me would be greatly appreciated. Thanking you in advance.

 

How about a new thermostat with a lower set point. How old is your water pump? How many miles on your truck? How big is the trailer??

 

As far as I know the water pump has not been changed. The truck has roughly 130,000 miles on it. I can't remember but I want to say the thermostat that is currently on it is a lower set point than the OEM. And my travel trailer is a 30ft trail lite by R-Vision. The dry weight is roughly 5700 lbs.

 

I'm sorry I just went outside to check the exact weight of my travel trailer, the unloaded vehicle weight is 4600 and gross vehicle weight is just above 6000. I responded to your message earlier but I didn't include your message. I hope my responding back to back is not a bother.

 

thermostat is a cheap and easy step to rule it out. put in the correct oem stat. cold stats can promote oil sludge build up if the engine runs cold all the time.
is the air flow thru the rad ok...check for plugged condenser fins blocking air flow thru the rad.

 

Good morning Tech2, I will check the airflow through the rad today when I get home from work. I've had both OME and cold thermostats in it, and there was no change with my issue. In my mind I was thinking all that is left is the radiator hoses, overflow reservoir or water pump. I'm not a mechanic but those were just my thoughts. If you can think of any thing else that I need to try let me know. Oh I'm not sure if this makes any difference or not, but if I have the a/c on and when the temperature hand runs up to overheating, the a/c starts cycling in and out and it blows hot air. It will not blow cold again until after everything cools down.

 

Go with the OEM recommended thermostat temperature rating which is 187°. Going lower will not only contribute to the formation of sludge, but it will also adversely affect the emissions system and increase your tailpipe emissions.

What does your coolant look like not only in the coolant surge tank, but also in the radiator? Is the cap on the coolant surge tank sealing and holding pressure?

If your coolant does not look clean and somewhat clear, there could be a buildup of crud in your cooling system which must be flushed in order to remove the crud and then a fresh DexCool-distilled water solution placed into the system. While at it, I would also change the radiator hoses, heater hoses, and other misc hoses as well.

Good Luck!

 

Good afternoon, here is an update: I replaced the water pump yesterday with a brand new one and I changed the coolant with fresh DexCool. I still get the same issue.

 

What did the old coolant look like?

Do you have a code reader/live data scanner that you can read the engine temperature with?

 

Yes I have a code reader with live data. What do I need to look at besides coolant temperature?