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Discussion Starter · #1 ·
Hi I have a 2006 GMC 2500 with the Duramax and automatic transmission with 40.000 miles. My truck runs way to hot when towing and whan I drive with my plow on. I have to slow down or stop to get the guage back down. It will trip the overheat light. It does not lose coolant. I understand that the plow will cause some of the problem however I have had trucks with plows for over 30 years and this different. To me it cant get enough air flow as it does it with the plow on or off and pulling a trailer with out the plow on. Any ideas would be great.
 

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hey fill out your signature! do you know if you have an lly or lbz? the LLYs are notorious for overheating problems. if that is the case there is a few threads on here about the induction problem. if you get a LBZ mouthpiece mouth piece it will really help out. the mouthpiece is what connects your air intake to the turbo. it is EXTREMELY restrictive on The lly motor

hope this helps
Reed
 

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The 06 lly's already have the lbz mp they are same engine just less hp. Did u try flushing you system?
 

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^^^^ he is right same motor just different tuning
 

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oh. my bad guys haha i thought all llys had that mouthpiece!
yep first year 06's were lbz motors with lly from the previous year tuning learn something new everyday:)
 

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Ok, have you tried the basics, like flushing the system, washing out the radiator stack, replacing the thermostats, things like that?

Does the fan ever come on when it starts to get hot? usually the fan will come on and cool it right back down. You'll KNOW when the fan comes on, it's unmistakable. I'm betting your fan clutch is probably bad.
 

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I think when a viscus clutch goes bad they lock up so the fan is always on.


So what about the fan? After it comes on does it cool off at all? How much and what are you towing?
 

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Discussion Starter · #10 ·
It cools down right away if I stop. When I tow its about 12,000 pounds. Also this is all during the winter months with the ambient temps at 30 degrees or less. I will have to pay attention to the fan to see if it roars. I cant say that I have heard it roar????. It just seems if I tow or have the plow on the system cant cool enough.
 

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You will KNOW when the fan comes on. It's unmistakable. You literally can NOT miss it, it's like a freakin jet engine lol. So I'm sure for some reason your fan clutch isn't engaging. My best guess would be to get a new fan clutch. It should come on way way before you ever get hot enough to set a light or anything. I guess I don't know if it defaults to locked or not when it fails, but in this case it's obviously not coming on when it's supposed to, so I'd replace it, and it sounds like that should fix the problem.
 

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The fan freewheels when it fails due to fluid loss.

When the truck is cold, give the fan a push. If the clutch is bad, it will continue to spin after your hand comes off it.
 

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Ok, have you tried the basics, like flushing the system, washing out the radiator stack, replacing the thermostats, things like that?

Does the fan ever come on when it starts to get hot? usually the fan will come on and cool it right back down. You'll KNOW when the fan comes on, it's unmistakable. I'm betting your fan clutch is probably bad.
like gr8 said, when you washed out your radiator stack did you just spray a pressure washer through the front, or did you remove the radiator and intercooler and wash them seperately? i had a similar problem on my rig a while back. i tried just washing through the front and what i could hit of the back several times but it didnt seem to help, i them pulled the rad and intercooler and they were still full of dirt and grass seed. it just looked like i had gotten them wet but never gotten anything out, there was only about 20% that i could see through but after taking them out and pressure washing them thuroughly it runs like a top.
 

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silly qustion--do you have the winter front on?
 

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Like gr8shot stated, you WILL know when the fan clutch comes on. KillerBee gave good advice about checking the fan clutch (to be done when the truck is cool and NOT RUNNING!!).
Fan clutch at NAPA is about $100 if I remember correctly. Replacement is easy if you have an air chisel. Use the chisel on the edge of the large nut to break it loose, then you can spin it off with your hand. Use the same to put the new one back on. Cool thing about these trucks is the 2 piece radiator shroud. Makes this job a snap! Check your serpintine belt. If it's due, this would be a good time to replace it as well. Good luck!
 

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Mine done the same thing with my last truck fan clutch was the problem napa has a heavyduty replacement that fixed my problem. It's really not bad to change. Take the top of shroud off leave the belt on hold the fan and break the nut loose with a adjustable wrench it's a piece of cake once u get the fan off
 

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