Hello, My family and I are venturing out into full time rv living. This is my first time owning a truck with this new venture and have a question related to my truck. We bought a 3500 dually 2008 Chevy Duramax Diesel with an Allison transmission. The truck runs great but has 200k miles on it. We are pulling a 2013 Keystone Fuzion 399 Toy hauler which is about 40 feet. The first day I drove it home the truck started to over heat on the way up a long hill. I had to slow way down to the whole way up the hill while the truck had to cool down. I know this is a big rig but is this normal when traveling/towing up hills? Is there anything I can do to prevent this from happening again? Thanks for any advice you can provide!Joel-

Joel75 wrote:Hello, My family and I are venturing out into full time rv living. This is my first time owning a truck with this new venture and have a question related to my truck. We bought a 3500 dually 2008 Chevy Duramax Diesel with an Allison transmission. The truck runs great but has 200k miles on it. We are pulling a 2013 Keystone Fuzion 399 Toy hauler which is about 40 feet. The first day I drove it home the truck started to over heat on the way up a long hill. I had to slow way down to the whole way up the hill while the truck had to cool down. I know this is a big rig but is this normal when traveling/towing up hills? Is there anything I can do to prevent this from happening again? Thanks for any advice you can provide!Joel-Try here: dieselplace.com

Have you ever cleaned the cooler area. At 200k I would suspect they are pretty dirty and buggy. Pretty soon the GM guys will chime in. Good Luck

I'd ask you to define "overheating". Did the radiator fan clutch engage?Factory gauges aren't known to be accurate but is it that reading that makes you think the truck was overheating?You should be able to hear the fan clutch engaging. If the engine got hot enough that the fan should've kicked in but didn't, then persue that avenue. If the fan kicked in but the engine temp still kept rising, it can be altogether different problems.Phil

Joel, I guess the first time you drove it, you had the trailer. Normally water temps will go up when pulling a load, going up a hill. But there are some things you might have someone check. Does the radiator have any flow restrictions, if it is equipt with a clutch fan & is it working right. Was the truck equipt with a tow package, thicker radiator, tranny cooler, etc.

Thanks for the feedback so far; to respond to you Phil,to be honest I'm not sure if the clutch fan kicked in, I will have to listen next time. How I new it was over heating was because the gauge was buried all the way and my air conditioner started to warm up and then the warning came on the monitor. That's when I pulled over to let it cool down for a bit and idle.

Newbie with Truck over heating | Good Sam Community

mapguy
Explorer
Aug 04, 2013
msjdbman wrote:
joegray wrote:
If you take it to a dealership or someone with a code/scanner computer they should be able to force the clutch fan to engage through the computer. That way you would know rather than just throwing parts at it. I would also put a new rad and thermostat in it that way you know it's clean with no restriction. JMHO

The fan clutches on these are an internal thermostatically controlled unit. They can not be forced to come on by anything other than heat. According to my dealer, they have replaced the clutch on many 08`s and 09`s. Mine included just 2 years ago now. My truck was doing exactly the same that the op described. As soon as the fan clutch was replaced, the issue was resolved.

This is 100% correct. If the fan doesn't engage the first start of day for a few minutes -it is probably not working correctly. Without it working correctly -the fan never actually fully engages to create the pulling effect needed. AC system not functioning correctly could also induce overheating....
chaunceyL
Explorer
Aug 04, 2013
Just got back from a 80 mile drive and only when under load can you hear the fan ... So I'm guessing its working from what I'm heading but why still overheat ? I'm thinking maybe its working but not working right ? And when idling same thing in temps around 95 same thing it wants to heat up ... I have a little pontiac with a 2.4 ecotec in it and that car will run all day at 190-200 with ac on while the fan just roars away so I'm thinking runng or sitting whatever's making it heat up has to be the same problem no?
jfritz_drfritz
Explorer
Aug 04, 2013
The thermostatically controlled fan is a bit like a torque converter, when it heats up a spring expands opening a passage which allows the fluid in the clutch to make contact in the other compartment with the vanes and thus engages the fan. The fan engaging in the morning at start is because fluid at rest drains into what I might call the active compartment and transiently activates the fan. I used to wedge the spring on my overheating jeep grand Cherokee to get better cooling at low speeds.the fan was ineffective at speeds above 3000 rpm but since we are talking diesel here (I hope) you might try that as a brief test to see if it makes a difference.
_40Fan
Explorer
Aug 03, 2013
Because the fan isn't electrically controlled, it needs heat to activate. If the radiator or anything else directly in front of the fan clutch is blocking air, it will never lock up.
chaunceyL
Explorer
Aug 03, 2013
And my fan doesn't kick on when I start my truck but I do live in so cal Orange County but it does come on on a long grade as its suppose to but seeing it doesn't upon start up could it still not be functioning right ? Because most say they can hear it when they start thier truck but I do not .... And also likes to get warm I've noticed if I idle to long when temps are 95+ towing or not ... Coolant if fool no leaks and I can hear fan .... Thanks if you can help !
chaunceyL
Explorer
Aug 03, 2013
Thanks cristglenn for the response, but I think I may have more of a problem. Just after Baker on I-15 towing just under 3,500 pounds with and outside temp of 95 degrees, the A/C was shut off and I still have the same problem....saw a guy towing north on same highway with same truck just a 3500 DRW towing a loAded about 45ft enclosed fifth wheel and didnt seem to have to break speed due to the heat , his windows were up so I'm guessing his ac was on so I'm thinking there is a problem not to mention all the plp on here saying "I haul that road everyday and temp doesn't get above 220. Where else do I direct my attention ? The. Cooling system it's self ?
6dot6
Explorer
Aug 03, 2013
U sure? In the winter when i first start driving the fans kickin ass. U sure it cant be overrided?
msjdbman
Explorer
Aug 03, 2013
joegray wrote:
If you take it to a dealership or someone with a code/scanner computer they should be able to force the clutch fan to engage through the computer. That way you would know rather than just throwing parts at it. I would also put a new rad and thermostat in it that way you know it's clean with no restriction. JMHO

The fan clutches on these are an internal thermostatically controlled unit. They can not be forced to come on by anything other than heat. According to my dealer, they have replaced the clutch on many 08`s and 09`s. Mine included just 2 years ago now. My truck was doing exactly the same that the op described. As soon as the fan clutch was replaced, the issue was resolved.
christopherglen
Explorer
Aug 03, 2013
The thermostats are fully open at 230. 240 avg is normal for pulling a mountain - and bouncing +- 10 degrees from there as the fan cycles. FYI if you are worried about overheating, shut off the AC for a few minutes (on the hill) and it lowers EGT's about 50 degrees - which will lower the coolant temps as well as the radiator having cooler air going into it.
chaunceyL
Explorer
Aug 03, 2013
Have a lmm with 253k and have the same problem no matter what I'm towing a ton or 10 to a still wants to over heat with any type of prolonged grade and can kicks on and temp stays up never all the way at 250 but 240 or so ... To high for me ... Rad is clean truck has straight pipe with EFI economy tune that's it .... Let me know if you figure out what's up with it

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