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01 Suburban 2500: Thermo not opening?/plow overheat
Ok so my dad's truck, pretty much since new has had this issue. If you have the plow on and don't let it get close to operating temp before you start driving, it will start overheating after about 20 min, regardless of terrain or how high the plow is. It will start going just above 210, then the gauge will start booking it towards 260 in a matter of like 20-30 seconds.
Mind you, if you pull off, shut it down, restart quickly and let it idle with the plow down on the ground, it'll cool down to regular temp (just under 210) in about a minute or so, and as long as you don't shut off the truck again, you could drive through a huge hill in the Sahara and the temp gauge wouldn't budge. Background: 6.0 motor was replaced under warranty and send back to GM at 33k miles due to a random rattle not found and literally like 3psi of oil pressure at idle, and maybe went up to 10-12 under throttle. Truck now has 188k miles. Is equipped with the tow/haul and plow packages. Thermostat was replaced 2 years ago in an attempt to solve the issue and hasn't change anything. It seems like the thermostat isn't opening right or something. |
Let it do the overheat thing then grab the top hose or take its temp. If its cold then the t-stat isn't opening. Could be the clutch on the fan is fouled up and not tightening when hot causing it not to spin faster. You could let the truck get to operating temp, shut it off, and try turning the fan by hand. If it freewheels relatively easy, I'd look into replacing the clutch fan. It should be tight and harder to turn when its hot and freewheel when cold. Only other thing is somehow the plow is obstructing radiator flow but I would think the overheating would be constant with it up then. Possibly some clogging inside the radiator, damn dex-cool!
Only relative tsb I saw.... Quote:
This explains fan clutch operation. Might have an issue with the fluid not properly heating. Quote:
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Thanks, I'm going to try this tomorrow and let you know how it works out.
Or next time it snows since I forgot I took off the plow last night |
are the fans on at all times regardless of the plow position?
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- Justin |
That still doesn't really explain how it's only the first time on startup though. Seems more like a hose is pinched when the plow is over the front of the truck, and once fluid goes through it the hose maintains its shape and is fine - the truck will NOT overheat once we get through that problem the first time for the rest of the time.
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the clutch fluid may not be warming up properly causing poor cooling at higher temps. its just a hunch though. I initially thought a pinched hose but you would have seen a leak by now from the abrasion.
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could the thermostat be sticky? and sometimes open all the way and sometimes get stuck and only partially open? drop it in boiling water to see if it pops completely open? Not sure if that could exactly happen, but i also dont know how dex cool effects the cooling system
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thats really odd....ive never heard of this before....is the temp. reading accurate? it is possible you are getting a false temp reading.....just a possibility
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Looked around on google a little, most people are talking about a HD clutch fan and some others are talking about the air shrouds. Someone mentioned a service bulletin but I don't have access to GM Service Information anymore.
The thermostat is on the water-pump assembly and the temp sensor is on the drivers side head. Is it possible that the engine is heating up unevenly? When you run with the plow and the increased load on the engine the block/heads may be heating up too fast to trip the thermostat. Not positive how you would fix that. lower temp thermostat, block heater or just continue to warm the truck up before you use it with the plow. |
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I'm going to try what Adam said about the fan tomorrow when the plow is on for the coming snowstorm. |
just threw that out there. every other suggestion makes sense too. to mee the fan clutch and shroud make the most sense to me
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I let it overheat on the way home from dinner and touched the hose on top...it was warm. not hot, not cold.
I'll check the fans tomorrow, I forgot about that |
Try turning the fan dead cold so you have some reference. It should spin pretty easy while hot will have significant resistance.
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