Electric Cooling Fans

[GasSavers_Randy]

I seem to remember that electric-clutch fans are common in semi trucks.

I think the aerodynamics of the fan is important. Most motor-driven fans are cheap stamped steel, where electric fans are usually molded plastic. That has to make a huge difference.

[DracoFelis]

Originally Posted by Randy

I think the aerodynamics of the fan is important. Most motor-driven fans are cheap stamped steel, where electric fans are usually molded plastic. That has to make a huge difference.

Good point. As I see it, cheap stamped metal would lose in two ways (compared to molded plastic blades):

1) The metal would generally have more mass than the plastic, and therefore require more energy to spin the thing.

2) And the shape of the blades is likely to be less ideal for moving air. Remember, it's very easy to use plastic molds to get exactly the shape you want.

[VetteOwner]

Originally Posted by DracoFelis

Good point. As I see it, cheap stamped metal would lose in two ways (compared to molded plastic blades):

1) The metal would generally have more mass than the plastic, and therefore require more energy to spin the thing.

2) And the shape of the blades is likely to be less ideal for moving air. Remember, it's very easy to use plastic molds to get exactly the shape you want.

yes, metal fans are usualyl straight finned blades, while electric fans have curved blades like little scoops that can blow more air using the same ammount of energey(ie run a motor at a constant speed using one set of blades measure cfm, then use curved blades at the same rpm and measure the cfm, im willign to bet alot that the curved blades work better)

semis are a totally different beast. first off thier made to be driven on interstates for long periods of time, think of the size of the electric motor you would need to turn that huge fan, semis are most liely loaded haulign alot of weight, where an efan woudl eb on all the time or cycling on and off causing the engine temp to constantly go up and down(heating and coolign of metal isnt good)

[8307c4]

To install an aftermarket fan to replace the clutch-driven one in a car takes a lot more doing than meets the eye. First there is thermostat location and fan installation itself, this all goes on the radiator and unless you are familiar with how these things are built it could just as easily spring a leak what with folks sticking and poking things through there.

But assuming all goes well, there is a time frame that takes months comes after that, and it specifically has to do with fine-tuning that thermostatic control to come on and turn itself off when it should... It can and usually will take more than one adjustment, the stupid thing will like to overheat on one end of the scale or it will run all the time on the other, there is a precise location on the dial that has to be found, by the owner, and this takes time... There are seasons, and it is possible it does well in summer but requires another adjustment for winter, and one does want to find that one sweet spot that requires nothing more of you, this takes the longest.

Last but not least comes the wiring. An electric fan needs straight battery juice to run properly, and the easy solution is to hook it up direct to the battery... Unfortunately doing this also allows the fan to come on after the engine is off, water temps rise in the first few minutes after ignition turn off, and then for about 20 or 30 minutes the temperature of the coolant will likely be higher than when the engine is running. This is normal, but with a battery-wired fan it also means the fan will keep turning itself on in short 1-2 minute bursts for some time after the engine is cut off.

All this takes battery power which must be recharged later, so the proper way to do it would be via a relay that is hooked into the ignition switch itself, and could be beyond most DIY'ers abilities.

Even if it saves no fuel, the assumption here is it does provide more horses, or more accurately the electric fan steals less power, thus making more power available to the engine... But I did this on a Thunderbird more so for gaining a few horses and if I had to do it all over again I would have left it alone, I felt absolutely no difference in a car that I drove for more than a few years. One might think the V8 made up for it, and maybe it did, but then what 4-cylinders (with the exception of performance vehicles) have clutch-driven fans?

Certainly no FWD's have them, and I do suspect most rwd's have them regardless of engine size... But I also think if there were a real benefit to be gained the mfg's would have produced more cars with the electric fans... If they don't care about the mpg (they don't lol) but they do care about horses, so...

[VetteOwner]

hahah nooooo manufacturers dont give a crap abotu horses or much into mpg. its all about COST and PROFIT margin...

every 4 banger truck i see has a clutch fan.

yes it dosnt accually create mor ehorses or torque but it frees up torque that ws once wasted by turning the fan 100% of the time (maybe not at full speed BUT still spinnign with quite a parasidic load) sure you wont feel much difference on an engine that already creates 300 hp...it has ALOT of extra horses and once you have that many horses feeeing up 2-5 isnt gonna make a difference... (same with really rich perople and money VS poor people, $50 might be a single entre at a resturant to the rich guy while the same $50 could feed 10 people to the poor guy)

yes you MUST run a Efan from the battery, as it draws 10+ amps on start up. Yes you must use a relay becuae like 8307 said it will run even with the engine off (1st hand experience at that one) all you have to do is find a switched ign scource, (liek wire off the wiper motor, etc,) to control the relay which doesnt draw barely anything.

wiring up relays is VERY simple, if you can install and wire up a thermostat then you can install a relay...(or vice versa)

it takes about 5 minutes to "tune" the thing all you do is start the vehicle up and watch the temp guage and when it reaches the normal position it stayed at with the clutch fan, turn the thermostat till it turns the fan on. might have to let it cycle once to make sure its goign to work then watch where it turns back on again. all of this takes like 15 minutes from a stone cold engine (most of this is from letting the engine warm up, i usually just drive a backroad and watch the guage, when it gets near i find a place to pull over, pop the hood and adjust it...)

then in the winter you may have to adjust it so the fan turns on later to keep the engien temps up but once again, takes a whopping 2 minutes on a warmed up engine.

to install the thermostat and relay just find a place where the tstat sensor wire is away from any battery terminals, hot things, or pinch areas then use a single sheetmetal screw to hold it down. then just run wires and 1/4" female spade crimp on connectors to it :P

the probe end of the sensor wire just wedge it in the cornner of the radiator near the hose that has the thermostat (the vehicle thermostat not the one your installing) by just very carefully wedgeing it between fins (can usualyl find a big enough hole along the edge)



i gotta get one of where i set everyhtign up

[gto78]

Hey, your brake fluid looks dirty.... just kidding, that pic is really clear and detailed though.

[ZugyNA]

I used a mechanical adjustable switch with a bulb and put it inside the top rad hose right where it clamps to the top outlet from the head. Get very precise operation of the fan. Tried it on the radiator...had a hard time getting it to work right. Good idea to cover the bulb with gasket goop to avoid corrosion?

[VetteOwner]

Originally Posted by ZugyNA

I used a mechanical adjustable switch with a bulb and put it inside the top rad hose right where it clamps to the top outlet from the head. Get very precise operation of the fan. Tried it on the radiator...had a hard time getting it to work right. Good idea to cover the bulb with gasket goop to avoid corrosion?

could you get another radiator cap and drill a hole thru it all big enough for the sensor to slip thru?

yes you can do that too, or slip the sensor into the upper radiator hose and run the wire out the neck (apply rtv around the neck so it doesnt leak) then tighten it down.

[s2man]

If it's got a bulb on the end, then the "wire" is probably a capillary tube. If so, I'd be leery of clamping the hose over it. But it sounds like it worked for ZugyNA.

[8307c4]

Originally Posted by VetteOwner

hahah nooooo manufacturers dont give a crap abotu horses or much into mpg. its all about COST and PROFIT margin...

every 4 banger truck i see has a clutch fan.

And I did say most rwd's have them regardless of engine size, and most trucks are RWD but you can check and see because I guarantee if there exist 4-cyl FWD trucks they have electric fans.

Has to do with how the engine fits under the hood, sideways engines have electric fans, and MOST longitudinal engines have clutch-driven ones.
And FWD means Front Wheel Drive, not 4WD.