First Tow Report - A+

[RVGuy]

We towed the TT for a nice bit of the trip this weekend. First time since installing all the mods. It did great!! I give it an A+ on all counts.

I do have one complaint about the 2500HD. What the heck was GM thinking when they designed that cooking fan that comes on every few minutes?????

How obnoxious can a fan be??? GM prided itself on the Duramax engine being quieter than Ford and Dodge. But in the cab, that darn fan noise was louder than the engine. Incredible. Anyone have a mod for that thing???? Please someone do something.

John Kennedy, you're an industrious kind of guy. Put some focus on this fan thing and let's find a solution. Good grief I can't believe how loud it is.

Did I say how well the truck towed???

[ThumbScott]

Towed for the first time on Saturday with my new 2002 3500 duramax/allison. All I can say is wow. This tows so much better then my 2500hd did. My fiver is heavy and the 2500hd was within specs. But boy oh boy what a difference. Tires on the dually didn't even bend. The truck sat down only about 1 or 2 inches. Impressive. I am very happy I went from the 2500hd to a 3500.

Just FYI, my fan is very loud also when I tow on larger grades. On the flat lands here it never runs loudly.

[ 08-26-2002: Message edited by: ThumbScott ]</p>

[RVGuy]

ThumbScott,

My observation regarding the fan was there was no rhyme nor reason as to when it decided to run.

In fact, I've had it come on first thing in the morning once or twice when the engine wasn't even up to operating temperature.

Has anyone had an issue with the fan and when it runs????

[GreyPower3500]

Don't be too alarmed about the engine fan running first thing when you crank up and drive away --- it's normal for it be engaged for a minute or so, something to do with the fluid in the viscous drive either being trapped or just too thick to release the fan.

Not sure why the fan's as sensitive as it is, but because of where it is (in the fan hub) it must see some wild air temp swings as load, engine and truck speed change. Also consider that the air being fed through to the fan has to pass through trans cooler(s), A/C condensors, intercoolers and engine radiator.

Hopefully someone'll jump in here with a technical explanation --- maybe even a fix !!!

[Lawnboy]

The cooling fan is a thermally activated unit. They've been around for 30+ years. When the air passing over them is hot, it expands a bi-metallic coil which turns a valve and allows the viscous fluid to engage the fan. They also run when you first start it up because that viscous fluid is rather thick.

As for the noise....Well, a LOT of 6.5 guys are adapting your fan to their engines....why? Because its QUIETER!!! And pulls a LOT of air.

For those complaining of fan noise....I guess you've never had a 70's, 80's, or 90's GM truck then. The old 5 and 7 bladed METAL fans were VERY loud, and in cabs that were NOT nearley as insulated from engine noise!

I'd say, Just be glad its working!

[Mike Colville]

I love the sound of the fan...if it wouldn't kill my milage, Id have it engaged all the time!

[Kennedy]

Couple viscous fan tidbits:

They typically will match engine RPM up to about 1300-1500 fan rpm (engine rpm x 1.25) in most conditions. When cold they will actually match more until the fluid is "pumped" out.

With the AC condenser, trans cooler and intercooler up front, more airflow is needed, and the clutch runs the fan more frequently. Fan engagement is necessary and a GOOD thing.

I'm certain in the future, there will be electric clutches in the aftermarket, but my take on these is that they can do more harm than good in some cases. The only reason I see currently for doing an electric clutch is for MORE run time...