I think the gauges just aren't accurate enough (sesitive enough) to show the small difference in temperature that it takes to make the fan come on. There is a change in temperature happening, you just can't see it on the dash gauges.

 

I'm glad to hear the info. I have never really pulled up a steep grade. My towing has been mostly a flat grade through MI, OH, and IN. I plan on taking my TT out west next year and I know that the sound everyone is describing would scar the tar out of me, if not prepared.

 

Oh dont worry my friend when it kicks on YOU WILL KNOW! It is very loud and scary the very first time you hear it. It starts as a loud droning noise in the vehicle followed by an equally loud "WTF is THAT?" noise inside your head (haha)

When it happened to me I immediately panicked and shut of the AC and the stereo so I could listen to this "new noise" and was freaking out the whole time but then realized that the noise had not affected my performance one bit which I thought was really odd and just as suddenly it went away.

I drove along for some time and it kicked on again and it was during this second cycle that I realized what it was and relaxed again, turned my AC and stereo back on and forgot about it. Once I got home I searched on this site for the noise and found TONS of guys who had, like myself, damn near crapped themselves their first time as well.

I no longer even think about it as when it does come on now. I know it is just doing it's job as designed. Relax my friend you will hear it one day and with all you have read here maybe you wont do as I did which was to fill the inside of your truck with profanity and scare the crap out of the wife and kids (haha)

 

I towed near 10k over Donner Summit past Tahoe to Reno-Fernley a month or so ago. The truck pulled like a beast no problems whatsoever. The fan did kick in a couple times as altitude/heat increased, but overall an easy tow! Love my 6.0. Tranny was stellar coming back down as well. Interesting info about the LLY.

 

It sounds like the truck is taking off like a jet.

 

yep....just like a jet engine spooling up. Now that I know what it is it gives me even more confidence in the truck.

 

I can confirm the fan has multiple settings based on engine coolant temp and possibly oil temp as well. I run an outlook monitor and my stock engine coolant and tranny gauge. Both dont move at all. Stock Engine temp ranges from 120F to 200 before it starts to move up past its normal spot. The fan comes on stage 1 about 205, stage 2 at 210, stage 3 about 212 (sound of a train.) based on the outlook. This vagueness also holds true for hte tranny, mine shows normal from 100F up to 190, I have never seen the outlook go over this even pulling and my outlook only shows 1 high of this level. My stock engine also has pyro, I have yet to get it over 1050 pulling, but summer is coming.

 

Bobmarlin, I love your post. When my 2007 PSD fan came on this month, nearly 4 months after I bought it, that is exactly what i said to my wife as we were going up a mountain road. Sounds like a tornado.