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Discussion Starter · #1 ·
Maybe I am just confussed....but my fan is on alot more than I think it should be. Engine temp was right were it was suppose to be, outside temp was about 45, and it ran all the way home on the highway and through town. I thought they were suppose to only be on when the truck got warm. It seems as if it just runs all the time. It doesn't sound like a Jet as some people have put it, but I can tell its on.
 

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I dont have a answer but i know my 04.4 auto dose the same thing the fans is always coming on and off for what seems like no reason at all! I never hear the fan in my 05, not even towing in the summer?????

If i figure anything out i'll let you know!
 

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are you using your cold front?? unless i am pulling or driving in sand in the summer across the beach, the only other time is in the winter with the cold front on, the fan gets "confused" because the temp sensor in the clutch has minimal air moving around it....
 

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Maybe I am just confussed....but my fan is on alot more than I think it should be. Engine temp was right were it was suppose to be, outside temp was about 45, and it ran all the way home on the highway and through town. I thought they were suppose to only be on when the truck got warm. It seems as if it just runs all the time. It doesn't sound like a Jet as some people have put it, but I can tell its on.
Can you get a boost gauge?

Also, can you hear it at idle?
 

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Discussion Starter · #6 ·
I don't have a winter cover. I took my truck in and they replaced the fan clutch but it still runs more than i think it should. when walking in front of my truck, all you hear is the fan over the motor. I haven't noticed this Fan doing it but the last one would pulse on and off. Hopefully next month I will have a little money to start working on my truck, need to find out quick because this is killing my milage. I went from 400 miles per tank to 320.....or it may just be this new fuel.
 

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Do you realize that the fan spins 100% of the time?

It never stops. It is a thermo-viscous design that requires it to spin at low speed at all times
 

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it might "spin" all the time but until the clutch engages, the fan is never 1:1 with the engine. there is no "load" with the clutch disengaged. Oddly enough the bended winter fuel or this new 2007 ultra-low sulfur bu&(*(@^t is all sorts of bad news for the LLYs. i have significantly more "top end" noise due to the injection pump not getting the lubrication that it was used to a few months ago. There is a ECM update that GM can do to help with the "pinging" but as far as the fan... thats a good question brother! did you get a GM replacement clutch or something after-market?
 

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Discussion Starter · #9 ·
yea I realize the fan spins all the time, but when it was pulsing on and off it would speed up and then slow down, thats when I really noticed it, when I first bought the truck I could not hear it at all. Is there any good additives to put in when I fuel up? I would really like some of my milage back.
 

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BG has a great diesel additive... I am using it and it makes a huge difference. Like i said before, the LLY passes the fuel from your tank through the injection pump once for lubrication of the pump itself, and to warm the fuel to a constant temperature & consistency before it is actually pumped through the injection pump to the injectors. The problem with this is that the new ULSD has no film or coating of oil like the old fuel did, so the lubrication factor is terrible, which causes the engine to ping, and that sound is your injection pump starving for lubrication. ITS NOT a good thing in my eyes. When i started using the BG additive, the ping was gone, the top-end noise under cold starts was gone and the mileage went up 2 points at least. The additive as well as the PCM update solved a lot of my problems.
 

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I forgot to list this in my last post...

BG 227D New BG Diesel Fuel Lubricant with Conditioner

BG Diesel Fuel Lubricant with Conditioner is a superior multi-functional fuel supplement. It provides the necessary film strength and lubricity to low-sulfur and ultra-low sulfur diesel fuel to prevent fuel pump and injection parts from scoring and seizing. This diesel fuel additive complies with the Federal low-sulfur content requirements for use in diesel motor vehicles. It will remove deposits from the fuel system and prevent their re-forming. Two ounces (60 mL) of BG Diesel Fuel Lubricant with Conditioner treats up to 40 gallons (150 Liters) of diesel fuel. Catalytic converter and oxygen sensor safe.
Part No. 227D 16 oz. (483 mL) bottle
 

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Jeromy

Have you ever had the fan clutch replaced?

If so, and you still have the problem in cooler weather, I have some ideas, but you need to get dirty.
 

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Discussion Starter · #13 ·
yes the Fan clutch was replaced by GM, as soon as the weather is nicer and I have an weekend to spare I plan on pulling the stack apart and cleaning it....only thing I can really think of is it dirty and creating a hot spot.
 

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If it is obviously really clogged up, then that may be your problem.

But many of these trucks have the same symptoms with no bugs. i was going to suggest something different.

Do you have a way to monitor VVT vane position? You would need a scanner, like EFIlive or Tech 2, or...
 

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One experiment to try, when you get a chance. Don't have to get dirty.

Run the truck in first or second gear (low speed), 3000 rpm for about a minute. What does the fan do? Is it louder than before?
 

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Discussion Starter · #16 ·
I will try that at lunch....right now I don't have any way to monitor it...The truck is bone stock. I plan on getting a tuner and exhaust this summer.
 

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Because you have had the clutch replaced, it suggests the clutch is doing what it was made to do, engage when it gets hot. Some is either delivering more heat that normal, or you have an air restriction.

The black radiator top cover is easy to remove. Pull it off and look down between the CAC and radiator for nests.

If it appears to be clear, I thing you may have a problem with heat in the CAC. It is not too difficult to pull the MAP sensor, located under the 6.6 black resonator hat. See if it is melted or damaged.
 

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what is your normal operating temperature? then what is it when the fan is on? will the fan run first thing in the morning with your truck cold? Was the "new" clutch a re-man? There is possibility that one is bad too.... replacement parts fail as much as part they are replacing... or there would never be a need for parts stores :D
 

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Discussion Starter · #20 ·
not really had a chance to work on it much. To answer the questions on temp....my truck has never got to the 210 mark. I have to take it in to get an oil change soon, so I might have them replace the fan clutch again.
 
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