Is there any real advantage? I just recently installed an electric fan on my 2002 S-10 in place of the heavy power robbing mechanical fan (and don't anyone dare say the mechanical fan doesn't take that much power to operate cause the main reason i changed it was because there would be times i would try to pull out in traffic and i'd be flooring it and its like starting out in 3rd gear and you could hear the fan rouring away, and my fan clutch is good because it was mostly when the engine was hot)..

but im wondering why trucks and SUV's have mechanical fans isntead of electric? and if there is any thing i should worry about having to do with the waterpump no longer have the weight of the fan being on there. like ballance or anything..

this new fan cools way better then the stock mechanical fan did. i can actualy see the temp guage fluctuate with the thermostat opening and closing, and the temp hasn't passed 210 yet, and this is with the a\c on full blast cooling better then it ever has. so i know cooling isn't an issuse, however i have yet to tow anything, which i know will increase engine and especialy tranny temp alot, but a tranny cooler is the next upgrade..

but pretty much my main question again is why mechanical when electric seems to be better?

 

I am pretty sure that they have a mechanical fan because trucks and vans spend a lot of time idling and going really slow, whether it be on a job site, or just plain working it hard in slow moving situations. It keeps the system cool at all times, not that an electric fan won't do this better, but the mechanical one will never break down or fail as long as the motor is running.

 

not to mention, a modern clutched fan doesnt rob power when not needed.....


unlike the old school fans like on early thirdgen.

 

Few things on the planet can move the kinda air that a GM thermo-clutch fan setup can. It uses a temperature-compensated viscous coupling that stays close to 1:1 with the water pump/engine at very low revs (idle) but slips like mad in the upper RPMs, keeping you from losing more than just a few HP to the fan. As a side benefit this means that the fan itself runs in a very limited, relatively low RPM range. That's a GOOD thing. That allows the engineers to design the fan with BIG HUGE, steeply angled blades that move a lot of air at low RPMs.

The only factory electric setup I have found that comes close is the 4th gen LT-1/LS-1 fan setup. Those suckers can move some serious air, but they also draw a lot of amps.

 

There is a lot more engineering that goes into the GM clutch fan
setup than most people realize.

GM actually makes many different clutchs for their fans to suite different applications.
Just like a torque converter these fan clutches have differnt coupling rates build in.

When matched with the matching fan size and pitch and pulley speed they move the most air, the most efficiently.

Its all a matter of matched components.

The roar you hear when you first step on the gas is the fan temperairly accelerating. It will stop roaring when the clutch decouples when the airflow is high enough through the radiator at speed. This is part of the design.
Some of the aftermarket replacements are not the same.
The GM clutch is dual action. it is regulated by temerature and
by speed and airflow through the rad at speed. (Overrun action.)
That why it costs more.

There is no free lunch. A electric fan takes electric power to turn.
The power comes from the alternater. The alternator is driven by the engine.

 

I always wanted to know why GM trucks and pickups made that noise when they were cold. This thread has taough me so much about mechanical fans. I had no idea that they actually had a clutch in them. You guys have made my night.

 

i understand that the increased load on the electrical system will put the alternator under a higher load which will require more power from the engine. but i remember seeing some #s somewhere that said how much HP the average eletric fan takes to run and its no where near the amount as the mechanical fan does.

but as far as the many diff types of fan clutches for applications, i experience that all the time working in an auto parts store. people come in wanting a fan clutch. and then 10 questions later about rear axle ratio and cooling needs etc etc and they finalyl have their fan clutch