WOW what a difference between the LLY and LBZ I have been test driving new trucks all of them so far have been the mighty LBZ/Allison well I have also been doing alot of studying on this site and learned alot mainly to stay with the LBZ but the salesman tried showing me this LLY equipped LT3 2500HD the price was good but you guys have taught me better but just out of curiosity we went for a test drive the first thing that I noticed was the cooling fan on light acceleration out of the dealership I thought I was standing in front of my 5 foot tall shop fan because off all the noise from there on it only gets worse we had to imedatly get on the highway to go anywere so I floor it waiting to get thrown into the seat but it just never happened I guess I was used to the LBZ but I didnt think it would be that much of a difference its only 50hp and 45tq this thing was worse than what I was expecting all this and it will probably overheat no thanks so I made the decision I will be going back monday to pickup my new 06 LBZ 2500HD :ro)

Congrats!

You'll still get the fan noise on the LBZ also, so don't be surprised.

is it just only when towing heavy loads I didnt really notice it on the other 3 LBZ trucks but the LLY was imediatly noticable even my wife noticed it and she was sitting in our jetta TDI

the 06 LLY and LBZ are identical motors with different programming

so you proboably could have saved a good bit of money getting the LLY and then throwing a tune on it

(EDIT: Shucks, took too long and BigShrimpah beat me to it! :-)

The LLY and LBZ engines are identical except for programming.

If the 2006 LLY you drove made more noise, then it is broke.

I had mechanics at two different Chevy dealerships advise me of this back in Oct before purchasing my LLY.

Lots of threads on this and other sites state the same (one pasted below, info found on page 1). They are identical engines part by part, bolt by bolt (except the programming is different); mechanics verified. I use the SuperChips programmer on mine because as your can view on their website for each engine's dyno plot, their programmer takes each engine to ~ the same HP and torque.

http://www.dieselplace.com/forum/showthread.php?t=72479

is it just only when towing heavy loads I didnt really notice it on the other 3 LBZ trucks but the LLY was imediatly noticable even my wife noticed it and she was sitting in our jetta TDI


No, I get it right when I leave the garage. After truck warms up it's gone.

No, I get it right when I leave the garage. After truck warms up it's gone.

On my new LBZ I get the fan on right as I start it if the air is on. It turns off in few miles or so. I am not sure if it is because the fan was on when I turned off the engine last or the engine gets hot enough for the fan to engage just after I turned it off last and it takes a little time for the fan to dis-engage. It's not everytime but, it is when the engine is cool. I heard of this on reading here so it wasn't a big deal. If I wouldn't have read about it first it would have been.

exactly