I read an article on fan clutch operation, and feel that mine may need to be replaced.
Under no driving condition have i ever had my vehicle sound like the fan was fully engaged.
I read that when you start up the vehicle in the morning, the clutch will be in the same position as it was when turned off. My 07 Silverado Duramax, sounds like a jet engine when i start it up, and after driving a block or so, it quiets down, and only sounds that way, when I am pulling over 8000lbs and up a steep incline for a good distance, and with A/C on. It quickly cools down and fan clutch disengages.

Now concerning my 03 D2, I do not have any overheating issues, in fact, after installing the 180 degree thermostat, My temps normally stay around 190-196, with A/C on and 90+ degree Texas heat. Given the fact that the electric fan is always on when the A/C is on, could mask the fan clutch not working.
I do plan on replacing the clutch anyway, but would the 00-02 fan and hayden clutch be a better choice than replacing with stock 03?
I have been following another thread discussing that option, and did not want to hijack that thread.
Any thoughts on the matter?

 

I'm suprised to see the 07 chevy has a mechanical fan. My dad's 07 5.3 Silverado has dual electric fans. Anywho.

If you are getting the desired temps then I don't really see the point in changing the fan. The sound at start up doesn't really matter anyway because the thermostat isn't open yet. The only real reason at this point would simply be age considering the number of fans the forum has seen explode lately because of dry rotting. I'm in the process of installing a two speed electric Ford fan that I got got $65 and if it works then I'll throw up an electric fan conversion write up. It's evidentally supposed to pull in the ballpark of 4000-4500 CFM on high. We'll see how it does.

 

Appreciate your input, the age of the fan and clutch are my biggest concern at this point. I understand that the thermostat hasn't opened up at startup, I was only comparing it to the chevy and the article said that was a normal operating sound for a working fan clutch(that is, being in the same state of operation as when shut off). It can be 30 degrees outside and the fan clutch is engaged when i start it up, until the fluid has a chance to return to the reservoir in the clutch. I have also been keeping up with the electric fan conversions, because that, to me is a viable alternative. i will be watching how your conversion goes.

 

I replaced both my fans in the last two days. The functioning viscous clutch masked the non-functioning electric fan until it (viscous) failed.

When my viscous clutch worked, I almost always had the roaring sound at start up, like your Chevy.

If I were you, I would replace the viscous fan clutch. I believe you are correct in that the electric fan is hiding the non-functioning viscous fan. When it fails, you will have serious trouble.

A Hayden 2991 is $58 on amazon. You will need a separate fan if you still have the one piece set up, but the whole job can be done in less than 20 minutes.

 

The whole job can be done in 20 minutes IF your fan wants to unthread from the pump shaft. I bought a fan from a 2001 in a junkyard so I could save a little money over going the one-piece route and when I went to install a new clutch I found that one of the 4 bolts holding it to the fan wouldn't budge. I snapped an allen socket off trying to loosen it. I will have to grind the head off so I'll be spending a little more than 20 minutes on this one. Of course, being in Texas you may not have to contend with rusted and seized fasteners.

 

That new Hayden 2991 that I bought doesn't have any roar or excessive blowing power. I can feel it pulling after I leave a long stoplight in the afternoon when its 100 degrees. when I was filling and bleeding the coolant I could feel it pulling air at a certain point but it was quiet. But I was definitely expecting to hear a lot more air being pulled.

 

The roar from a fan is not the clutch, it is the fan moving air. The clutch has 2 separate parts that are free to rotate independent of each other. There is fluid inside the clutch that normally resides in a reservoir chamber on one half of it. There is a bi-metallic coil on the front of these clutches that is connected to a valve. When the radiator gets hot, the coil turns the valve and allows the fluid to flow from the reservoir into the fluid chamber where it allows the driven side (on the water pump) to couple with the fan side. Once the coolant temp drops, the coil closes the valve and the fluid then drains back to the reservoir.

The reason why they usually make noise when cold is that the engine is typically hot when the car is turned off so the fan has been turning and the fluid is still in the chamber. When you start the engine, the fan is still coupled until the fluid is able to bleed back out to the reservoir.

 

lmao, by "hearing a roar" all I meant was that since I couldn't hear it, (not literally a roar from the mechanism itself but from the sound of the air being pulled through) that I was unsure of its performance being as it brand new. I've read all I will ever need to know about a flippin fan clutch.

 

Nice explanation. I've never quite got my head around it.

 

The still engaged at startup thing was always the part that made no sense to me. I'm not sure why they stop working. If the fluid is still inside and the coil is still attached to the front you would think that the thing would keep working.