We pulled our 5th wheel on a 150 mile (one-way) trip this past weekend. I was pleased overall with the performance pulling a 17k lb. 5er. The increased horsepower combined with the new 6-speed Allison and Tow/Haul mode makes for effortless towing.

However, I was quite displeased to hear that the noisy cooling fan had not been remedied by GM. In fact, the sound level of this new fan is even louder, in my opinion, than the cooling fan noise I experienced in my 2002 and 2005 model trucks.

I can not believe GM can't seem to engineer a cooling fan with less noise. For those who may not have had the pleasure of hearing it; I would not be exhaggerating if I said the noise level exceeds the 90 db level. When it first came on, my wife asked if there was something wrong with the engine.

RV Guy

I'll be taking delivery of a similar TV tomorrow and will be towing at your level. What are you towing?

Had a 454 equipped 86 GMC CC 4X4 Dually and its fan came on and off, when towing, every 4 or 5 minutes IIRC and sounded like a turboprop plane taking off! It would cool the radiator temp gauge down about 40 or 50 degs, and then cut off and the cycle would start all over again!

My current LB7 towing pretty heavy, will kick the fan in to the point where I can hear it, but you really have to be pulling a long hill. A lot of time I don't have the radio on, and DW and I are just talking and the fan noise isn't a bother. Hope you can get yours to quiet down some.

The fan is loud!

Mine fan also seems to stick on in the morning once and while....

chinook47,

I am now towing a 36 foot Mobile Suites Deluxe made by Doubletree RV. Its GVWR is 18k and at the scales it weighs in right at 17k with a kingpin weight of 3,200 lbs.

I am right at the trucks capacity. We did have the need to make an abrupt stop for one of those quicky yellow stop lights and the truck, Prodigy controller and 5er did a great job of stopping.

I'm very happy with the combination, but wait till you hear this fan. Holy cow what a noise. Worse noise I have ever hear any truck make.

RV Guy

My fan gets quieter after about 2 minutes from startup.

I also notice that the fan seems louder on tow/haul then regular mode.

If it makes you feel any better the fan on my friends 06 Powerstroke sounds like an airplane taking off, plus it runs way too often. I agree they need to come up with a better solution. I only have 420 miles on my LMM and haven't hooked it to the trailer yet, but I will find out soon enough. The fan on my 02 Dmax could be annoying at times, mainly when towing in the summer with full AC.

If the fan's not electric, how would it know if the truck is in the tow/haul mode?

Mine only kicks on in the morning for a little while, while it's still cool. No biggie. I would rather hear the fan for a short period than a rattle box diesel all the time, not that even that applies to the new Duramax.:D

RV Guy, thanks for the info, I can hardly wait till we can tow ours. Noise or not! Will probably weigh about 17K also and do you have the integrated brake controller? Hydraulic brakes? I will / do have those and hope they are compatible. I see that you have the Prodigy, but wonder if you are using that because of compatibiliy issues. My current TV has the Prodigy and it works flawlessly with the Disc brakes.

just my point of view they always will have noise, just like semi have you guys ever heard there fan? you will be surprized on there sound level.
but it would be nice to have quieter ones

RV Guy,
I'm sorry to hear that the fan noise hasn't been remedied on the LMM's. It's really annoying to me on my LB7 also. You would think the General would have caught on to the electric fan advantage by now...ah well:rolleyes: . Glad you are enjoying your new baby otherwise.

chinook47,

Yes, I run the Prodigy because the GM controller is not compatible with the electric/hydraulic brakes on the RV. Not only that, but the wiring harness for the Prodigy has to be slighly modified. They had to run a dedicated wire from the Prodigy to the back side of the plug in the back of the truck. This is the blue wire that carries variable voltage to the RV brakes from the controller. Good thing my RV dealer had already ran across this issue before and knew exactly what to do. Hope you have a good time towing your RV.

I towed a 15K 5er over 600 miles and never once heard the fan come on and I ran hard up hills. Much better than my LB7:D

Yes you are correct the fan it loud! towing 17-19k with my dually it has come on many times in the first 3k of its life but is runs cooler than my lly did.

How many miles did you put on the your truck before pulling your trailer?

I only have 2,000 miles on sig. TV and am not towing as heavy as the others, I'm under GVWR of my truck by about 500# and GVW of 5er is 14,500# with pin weight of 2900#. I have towed in the mountains of WV,TN & NC with this combo so far, and it beats THE CRAP out of my 05 LLY and I've yet to hear the fan come even close to being as loud as it was on the 05. In fact, I rarely hear it. Guess if I were towing heavier it might come into to play, but I've pulled some long steep grades in some pretty hot, humid weather and it's "quite as a mouse" compared to the 05 LLY, which seemed to run all the time and suck huge amounts of HP from the truck. I'll take this one anyday.

As per the owners manual, I put 500 miles on the truck before I started towing.

This is interesting to hear reports of the fan not coming on at all for others while towing. Makes me wonder why mine seems to fire up like it does. Does anything have any thoughts that it could be something other than the cooling fan?? I will say this fan does not sound the same as the cooling fans in the two 2500HDs I've owed. This one is much louder and sounds more like a turbine jet engine. I should also note there were no lights or CES indication. Am I thinking this was the fan and it was something else????

Where are you doing your towing? In the mountains? Don't take it the wrong way, but if your towing a 17,000# 5er, you almost have to be over the Trucks GVWR...and don't get me wrong, I've done the same thing, so it's not a "bash", but I wonder if my fan might not kick on more if I were towing a 5er that weighed the same amount yours does with my truck? I do know one thing, after owning and towing my 5er with the 05' K3500 same configured truck, I've yet to hear anything as loud as the fan that was on the 05', especially when towing. That is why I said, compared to the 05', the 07 is not loud at all.

My LMM will engage the fan while towing my 26ft ~7k trailer up some long grades. Given how quiet the truck is, when the fan wakes up it sounds like it's about to vacuum up small cars ahead of me. The racket is not long lived though. Even my ancient '89 Dodge Cummins would howl when the fan engages.

I've also had the fan (in either truck, actually) get 'stuck on' in the morning, especially if the last usage of the truck had been in warm weather. I guess I am used to it.

I also can see how in tow/haul mode, the fan can sound louder, as the truck is kept in a lower gear for a longer time while accelerating, and if the fan happens to be engaged when I am braking and the Alli decides to play jake brake with the engine at over 3400rpm, it sounds as if the fan will propel the entire drivetrain through the grille at any moment.

RV Guy,
I'm sorry to hear that the fan noise hasn't been remedied on the LMM's. It's really annoying to me on my LB7 also. You would think the General would have caught on to the electric fan advantage by now...ah well:rolleyes: . Glad you are enjoying your new baby otherwise.

Electric fans cannot pull air like a mechanical fan can! Real trucks have engine driven fans.It would take a fan that pulls 500amps of current and costs a couple thousand dollars to match the engine driven fan.Then it wouldnt fit in the space for it.If they had dual 12"electric fans only for cooling,without increasing the radiator size,the truck would overheat much easier in severe towing conditions.

Real loud fan here towing does not make as much of a difference as outside temp ! In hot weather my fan is mostly on ! even while empty

In the morning it is always on for a few minutes

How loud is it ?? way louder than any Semi or ten wheeler that I have ever driven or heard ( been in and around trucks all my life )

This fan is stupid loud and very aggravating , My series 60 DD fan moves allot more air than my LLM and it will scare the shit out of you when the air clutch kicks in but it is not as noisy while running and it does not have the high pitch whine of the LMM ! gotta B a Better way ? t

mine sounds fine,just turn up the stereo

RV Guy, check out old posts on the hose going to / from turbo, blue I think. IIRC some had issues with the hose clamps not clamping under high boost and there being a noise similar to what you describe.

On the Prodigy, is there still a pre-made electrical harness that plugs into the truck and then you have to run the blue wire? Thanks, and good luck with the noise.

chinook47, the Chevy dealer did the wiring. I just relayed what they told me. I can see the harness when I look under the dash. And it looks like it terminates into the connector box as in previous models I've had. And I can see the blue wire they ran directly to the rear of the truck.

Thanks for your hint on checking the turbo hose.

As to the suggestion that simply turning up the stereo will mask this noise. If they actually heard what I'm referring to, they would know that isn't possible.

good to know that overall your happy

They could make it quieter by increasing the diameter and decreasing the pitch. Trouble is, people would cry that the trucks weren't pretty enough because the grille would have to be bigger. It's a truck, if you want quiet and plush, you're going to have to drive a car, or an even bigger truck to haul around all of the amenities to you candy-butts need to make a trip!:) 17k 5er? I hope that wasn't for 2 people, that'd take roughing it to a new low!:eek: You need to get a bigger truck if you're going to take the whole estate.:p:

I've towed my ~10,000# 24' enclosed car hauler about 2,800 miles on a couple of trips in the past month and I've never heard the fan make any noise.

When I first start it in the mornings, it raises a bunch of hell, but after it warms up that noise goes away.