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Truck issues

Clay Showalter

Southern member northern landowner
6,401
145
Guilford County
I know a young man that owns his own business works hard, he is having some issues with his truck. Thought I would ask all of you smart guys on here.



2009 Silverado 2500 6.6 turbo diesel
248k miles

It overheats, turns my AC off, and I have no heat during the winter time
It overheats every time I drive it. I haven’t lost power, hasn’t affected the driving at all. I put new radiator, New thermostats, New coolant temp sensor. I have stopped to check the engine when temp gauge said was running hot, and it’s not actually hot at all. That’s why I changed the sensor, I thought maybe it was throwing false code but it wasn’t that either. Cools off quickly and is drivable Again, or When I hit like 55 mph consistent but then the gauge goes back down and the AC turns on again. It does this under when hauling, but also does it when driving just the truck itself.

I am thinking maybe exhaust leaking into cooling system.
 

5Cent

Dignitary Member
Supporting Member
12,291
212
North Central Ohio
There's 2 t-stats, and fan clutch sounds like possible issue since it's cooling off quickly on shut off. Weird it thinks it's hot, but actual says no.
 

giles

Cull buck specialist
Supporting Member
Sounds like multiple issues. It also doesn't sound like the antifreeze is being circulated properly. I believe those are the years that the system needs burped. Some goofy process with parking on a hill.
 
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Quantum673

Black Hat Cajun
Supporting Member
If it is showing hot but not really hot and the temp gauge goes down fast would point me in the direction of computer or sensor/wiring. Could be air in the system causing poor circulation but I would think that would cause a true overheat. Sounds like they are not truly overheating but are getting a funky reading.

is it throwing any codes?
 

giles

Cull buck specialist
Supporting Member
If it is showing hot but not really hot and the temp gauge goes down fast would point me in the direction of computer or sensor/wiring. Could be air in the system causing poor circulation but I would think that would cause a true overheat. Sounds like they are not truly overheating but are getting a funky reading.

is it throwing any codes?
What about the no heat?

I think the AC is unrelated. Could be a number of things with it. Condersor freezing or the clutch fan would be a good start.
 

Quantum673

Black Hat Cajun
Supporting Member
What about the no heat?

I think the AC is unrelated. Could be a number of things with it. Condersor freezing or the clutch fan would be a good start.
Depends on what they mean by no heat. Is the air blowing cold when on heat setting or is it shutting off the heat like it is the AC?

If it was the head gasket the temp showing on a temp gun would show overheat as well I would think. I have seen them do crazy things that end up being a head gasket so it is possible.
 
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"J"

Git Off My Lawn
Supporting Member
56,741
274
North Carolina
How old is the water pump? If it hasn’t been changed and has a boat load of miles on it, the fins on the pump could be worn down too nubs and not circulating the coolant good enough under a load.
 

Jackalope

Dignitary Member
Staff member
38,841
260
My 7.3 has a pressurized cooling system. Is his dgas coolant bottle puking coolant? Mine had a small crack at the bottle neck and the coolant level would rise and puke out. This creates air in the system which causes overheating and no heat as there isn't any hot coolant circulating through the heater core.

To eliminate a head gasket he needs to check his oil for coolant and his coolant for oil. He can also get a head gasket leak detector from autozone tool rental. You place it over the coolant fill hole and pump a bulb that draws air through a liquid that will change colors in the presence of combustion gasses.

If all of the above is ok he needs to park it on a steep hill and squeeze the upper radiator hose while it's running to burp it. You shouldn't have to do this but sometimes air can get trapped.

If that doesn't work then he needs to check if his water pump is working. Take off the discharge hose off the pump and crank it for a hot second. He'll know quick if it's moving coolant because it'll blow out.
 
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