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I have a 2004 duramax, Every summer when tempatures began to rise to above 75 degrees, My truck sounds and responds differently. Kind of like when you drive your first half mile in the winter, when the motor's cold. During this time, I never run it hard and pull easy because it just sounds like its working to hard already. But in the winter, it's very strong. Has anyone ever heard of this?Thanks
 

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Discussion Starter #2
could it be

I have a 2004 duramax, Every summer when tempatures began to rise to above 75 degrees, My truck sounds and responds differently. Kind of like when you drive your first half mile in the winter, when the motor's cold. During this time, I never run it hard and pull easy because it just sounds like its working to hard already. But in the winter, it's very strong. Has anyone ever heard of this?Thanks
Could it possibly be sucking my radiator hose flat?
 

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VAGITARIAN :)
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So what are you hearing the engine fan more?I sure don't get it......
 

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Discussion Starter #5
could be the fan

So what are you hearing the engine fan more?I sure don't get it......
It could be the fan but seems to be to loud. no knocking just roaring. Does this every summer. Reminds me of how it sounds when it is real cold for that first half mile.Thanks for your interest in helping me out to all who respond.
 

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Discussion Starter #9
Thanks

Maybe I should try pulling the fan fuse, temporary of course, when it is already making it's noise, just to verify. Or maybe not, You guys must be right, It must just be the fan. It sure does roar. Not in a broken way, just very loud. Thanks again.
 

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Rode the Short Bus
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Your truck will respond different to changes in ambient temperature. Engines like cold air much more.

The other guys are right though, you are most likely hearing the fan. but even without it, you might notice differences in the way the truck sounds when it is hotter outside, especially differences of 50F or more.
 

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in the winter, colder air makes more HP
I know cold air is better, but my truck runs way better in the summertime than it does in the winter. IDK why, but it does.
 

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read up on turbo mouthpiece for your truck. If you have the LB7 motor, never mind. But if you have the LLY, you need to do the mouthpiece swap. The turbo is working hard to get the correct amount of air and causing everything to get hot. Change that out and you will notice a huge decrease in fan activity during the hotter months.
 

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Rode the Short Bus
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read up on turbo mouthpiece for your truck. If you have the LB7 motor, never mind. But if you have the LLY, you need to do the mouthpiece swap. The turbo is working hard to get the correct amount of air and causing everything to get hot. Change that out and you will notice a huge decrease in fan activity during the hotter months.
Good point Diesel guy. I didn't consider that he could be an LLY.

The LB7 can benefit from it some, but not significant like the LLY.
 

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Its just a worktruck
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I always let my truck warm up before I drive it. Even in the hot weather. It helps to limit fan activity for your first few miles.
 

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XBoxLive: RenegadeDuramax
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in the winter, colder air makes more HP
Depends on where you live. You won't make any power until you're engine temp is over at least 160. My truck won't even warm up to 190 during the winter. It hovers around 170 - 175. I can feel a difference in power when it's warm.

Yes, cold air in your intake will make more power... but if the engine can't reach op temp... you lose power.
 

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The first time I heard my fan (really heard it), I was pullin my fifth wheel in 105 degree heat, doing about 65 miles an hour !! The fan kicked in and I thought a semi truck was passing me up it was so loud !~!
 

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Discussion Starter #17 (Edited)
Sounds interesting

read up on turbo mouthpiece for your truck. If you have the LB7 motor, never mind. But if you have the LLY, you need to do the mouthpiece swap. The turbo is working hard to get the correct amount of air and causing everything to get hot. Change that out and you will notice a huge decrease in fan activity during the hotter months.
I don't know if it's a LLY??? What exactly are you refering to as mouthpiece? Air intake before the filter?Thanks for your time. I have 2 more issues, will be another thread, that your knowlrdge of these trucks would be appreciated.
 

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If the 8th digit of your VIN is a 1, it's LB7, 2 it's an LLY.

The mouthpiece being referred to is directly after your air filter box. There are a few guides here on DF you can follow to upgrade it to a LBZ piece.


My truck does exactly the same thing. As soon as the temp rises above 70 or so, it gets hot and the fan kicks on and robs HP like crazy. I haven't done the mouthpiece replacement yet, so I can't say from personal experience, but a ton of people on this forum and everywhere else seem to swear by it so it couldn't hurt to give it a try.
 

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A mouthpiece is the tube coming from your turbo...stock they have a small opening to suck air in but if you get an aftermarket one or do your own mod which you can search for on this site, it opens that hole up so that your getting way more air flow... and fill out your sig, it will tell us what year your truck is and find out what kind of motor you have!
 

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If the 8th digit of your VIN is a 1, it's LB7, 2 it's an LLY.

The mouthpiece being referred to is directly after your air filter box. There are a few guides here on DF you can follow to upgrade it to a LBZ piece.


My truck does exactly the same thing. As soon as the temp rises above 70 or so, it gets hot and the fan kicks on and robs HP like crazy. I haven't done the mouthpiece replacement yet, so I can't say from personal experience, but a ton of people on this forum and everywhere else seem to swear by it so it couldn't hurt to give it a try.
are you sure there not refering to the turbo mouthpiece? You may be right but from what ive seen the mouthpiece everyone talks about is part of the turbo not air box...
 
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