New noise that has me concerned...

[HGDMARTN]

Several times in the past week I have experienced a new noise that has me baffled. Both times I heard it as I was pulling away from a stop in 2nd gear. (6sp) The engine noise was noticeably louder until I clutched and went to third, then normal. It sounded as if my RPMs were higher than they were. So not an abnormal noise, just abnormally loud for the range I was in(2000-2500rpm). Almost as if the fan was running faster or something. I was not racing or anything, just normal driving.
Anyone have any ideas?

Thanks in advance.
David

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'00 2500QC-LWB 2WD 6sp. loaded with a bunch of goodies that I would not have ordered if I bought the truck new.

 

[Arcticat]

It's the sound of your fan clutch being engaged as opposed to freewheeling. Scared me too this spring until I thought about it for a second. Drive around with your windows down and you will notice that it will engage and dissengage, causing the noise to appear and then go away.

 

[work2muchplay2little]

I agree with Arcticat, see if there's a difference in sound right after start-up (when fan clutch not engaged) compared to after warmed up. Also check to see if there is excessive wobble of the fan on the clutch (should only be a slight, maybe 1/16th inch movement at end of fan blades), and see if you can spin the fan by hand when it is cold as well (both bad).

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Kurt Voss
********* 1999 2500 24VCTD AUTO 4x4 QC LB Laramie SLT, Luverne stainless steel nerf bars, 3 piece bug deflector, mopar mud flaps, Line-X bedliner, Blue Chip Fuel Management System (Premium), Psychotty Air, DD3's,TTPM, DD 4" exhaust, HX40, DTT VB/TC(91%) , Mag-Hytec transmission pan... YEEEEEHAAAA!!
2000 4x4 Z71 Tahoe, all options, rear AC, brush guard, nerf bars, mobile video system, after market 3rd row seat... the ultimate urban assault vehicle!

 

[HGDMARTN]

Thanks for the info guys. As info- I can spin the fan while the engine is cold and this noise is something that has just come on recently. I ride with the windows down almost all the time and I never noticed it prior to last week. Did not do it any today. What do I need to look for next? Sounds like I have a problem.

What is the function of the clutch on the fan anyway? I know nothing about this.

Thanks.
David

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'00 2500QC-LWB 2WD 6sp. loaded with a bunch of goodies that I would not have ordered if I bought the truck new.

 

[Nemies]

It's not a problem; it's normal operation. When it gets hot enough, the fan clutch engages to pull more air through the radiator to help with cooling. Freaked me out too when I first heard it, too. #ad




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Kees C.
99, 4x4, 2500, 5spd, HD, LSD, SB, QC, Sport, Forest-Green, Cab-Lights
Rhinoliner, toolbox, dual Firestiks, always-on windows