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Truck overheats when driving speed limit

Tiny
CHARLESNOSEFF
  • MEMBER
  • 2005 DODGE RAM
  • 4.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 12,000 MILES
Runs at normal temperature while idling. But it overheats when driving speed limit. New: radiator, water pump, clutch fan, thermostat, coolant reservoir. After it heats up I can pull over and let it idle and it will cool back down. Motor was just installed. Had 120,000 miles on it. Motor runs great. Please help.
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Sunday, February 9th, 2020 AT 11:01 AM

9 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

This sounds like it could be a problem with the tension on the drive belt for the water pump. Can you please check and ensure that the belt is not slipping and get back to us with what you find out.

Thanks,
Alex
2CarPros
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Sunday, February 9th, 2020 AT 11:52 AM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
I'll check and get back to you. At a funeral now.
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Sunday, February 9th, 2020 AT 12:04 PM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
Checked belt. The belt was routed wrong. Would have never seen it if not checking the tension. Thanks so much.
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Sunday, February 9th, 2020 AT 2:26 PM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
Belt is installed correctly but still getting hot. What's puzzling is top of radiator gets hot but the bottom is still cool. Only thing I can guess is thermostat is not opening up all the way.
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Monday, February 10th, 2020 AT 12:08 PM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
Or maybe one of the hoses are sucking together and restricting the water flow at high speed.
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Monday, February 10th, 2020 AT 12:11 PM
Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

That sounds like a distinct possibility. Also I might add doing a cooling system flush and fill as well. Here is a link describing how to do it below:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

In the diagrams down below I have included the instructions for the removal and installation of your vehicle's thermostat. Please go through these guides and get back to us with how everything turns out.

Thanks,
Alex
2CarPros
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Monday, February 10th, 2020 AT 9:31 PM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
While my truck was in shop waiting for the new motor. My radiator, fan shroud, transmission cooler and power steering cooler was stolen. So they said. I got my truck out of shop and hired a mechanic to swap the motors out. It has all new cooling system with new coolant. This is after my truck sit in the shop for two years. Thinking about taking thermostat out and running it to see if it still gets hot. I sure thank y'all for helping me out with this problem.
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Tuesday, February 11th, 2020 AT 10:57 AM
Tiny
CHARLESNOSEFF
  • MEMBER
  • 7 POSTS
Forgot, I had put new water pump and thermostat in old motor before they told me it needed another motor. So it sit for two years without any coolant in it. So thermostat was dry the whole time. Thanks
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Tuesday, February 11th, 2020 AT 11:01 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,081 POSTS
Does the radiator have a shroud? If not this is causing the problem also let's double check the belt routing because if you are turning the water pump backwards it will cause this as well. Check out the diagrams (below). Please let us know what happens.
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Friday, February 14th, 2020 AT 10:34 AM

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