Good and bad of having a Thermo fan instead of belt driven?

Crackerjack · May 12, 2017

Heard some tales of people swapping out belt driven fans on older cars and adding electric thermo fans, said they gain some more HP and is more efficient for the engine.
What's the hearsay on tractors ?

Geo-TH,In · May 12, 2017

I think the reason they switched from belt driven fans to electric is to save horse power, get better mileage.

Might be too if they upgrade engine on old cars they may want more room and go with a serpentine belt.

I can't see what is bad about electric fans, unless you have to replace it. Don't need a fan at high speeds.

My Kawasaki mule has electric fan and electric assist power steering. Not sure if cars have gone with electric assist steering, but it nice on the mule.

Steve@Advance · May 13, 2017

I think there would be little gained.

Cars can get away with electric fans since the fan is only needed at idle. Once the car is moving it can cycle off, a fuel economy measure.

But a tractor fan would need to run constantly, and would need the ability to move air under adverse conditions, such as when the radiator is packed with grass.

Probably be more problem than it's worth unless needed for space saving because of modifications, repowering, etc.

JD Seller · May 13, 2017

Geo-TH,In; I have an 2002 Saturn Vue that has the electric power assist steering. Works fine.

coshoo · May 13, 2017

Electric fans are often put in hot rods for 2 reasons- too little space between the radiator and the larger engine for a fan, and to push more air through the original smaller radiator such that it will still cool the big engine.

craigco · May 13, 2017

I tried an electric fan on an Oliver 70. It moved enough air to hold a shirt on the radiator. Radiator was redone at a radiator shop so it was good. It would overheat in a very short time. Didn't matter if it was pulling a sled or running down the road for a joy ride. Put the engine fan back on and hasn't been hot since.

Moonlite37 · May 13, 2017

I have seen a couple old Chevys running without fan blades, One on a pickup and it worked well until pulling a load or driving in the city. It had thrown a blade out the side of the fender and the owner just cut off the other 3 blades/

John T · May 13, 2017

Cracker, good question. I'm NOT going into the differences and advantage or disadvantages ESPECIALLY not comparing a lowwwwwwwwwwww speed tractor to a high speed vehicle, but will just take an engineers perspective to your question:

"said they gain some more HP and is more efficient for the engine".

Not sure how much HP IF ANY is to be gained from using an electric fan, its certainly NOT any free energy device. It takes engine HP to turn a fan if its belt driven and it takes engine HP to turn an alternator to power a fan (via battery) if its electric WELL DUH. I just don't see much if any HP gain by using an electric fan versus belt driven.

Also an engine may be more efficient once its up to operating temperature, say 180 T stat setting. When cold it may not be as efficient so regardless if a belt driven fan or an electric fan controls the temperature and so long as the most efficient temperature has been achieved WHATS THE DIFFERENCE IN HP REGARDLESS OF A BELT DRIVEN OR ELECTRIC FAN (subject to if electric is more or less efficient then belt driven)

AGAIN (before anyone has a calf) this does NOT consider dirt or dust or air CFM air flow and speed etc etc. I'm ONLY considering belt driven versus electric (alternator and battery) driven in a low speed tractor IF ALL ELSE IS EQUAL AND MOST EFFICIENT TEMP IS ACHIEVED I don't see much HP gain

That's my story n Ima stickin to it

John T

Brendon-KS · May 13, 2017

One disadvantage of an engine-mounted fan on an engine that has isolators between it and the frame is that the fan tip clearance must be large enough to account for the engine movement. With electric fans the blade-to-shroud clearance can be held very tightly which increases the fan's efficiency.

Hydraulic fan drives are becoming more common on ag and construction equipment because they provide the variable-speed benefits of electric drives but with far greater power capacity. When you consider that a typical off-highway engine puts about 10% of its power into driving the cooling fan it becomes obvious why normal 12V electric drives aren't suitable for these applications.

Geo-TH,In · May 13, 2017

John
Do you remember de-clutching fans? That's was to remove the fan load at high speeds.

geo

4wdtom · May 13, 2017

I ran my 86 Dodge pickup with no fan for years. I seldom took it to cities with traffic though. Town traffic was OK as long as you got to move between stop lights. Moving down the road no problem even in summer. A tractor working at slow speeds would need a fan I am sure. Possibly over the road if it was a fast tractor, 15 or 20 mph, maybe not.

Hobo,NC · May 13, 2017

(quoted from post at 10:04:58 05/13/17) Heard some tales of people swapping out belt driven fans on older cars and adding electric thermo fans, said they gain some more HP and is more efficient for the engine.
What's the hearsay on tractors ?

It would take a robust charging system that most of yesterdays tractors don't have even the ones converted to 12V. Electric come in cheap and expensive cheap has never cut it on a conversion for me.

A neighbor with a nice 66 elcomeno spent 10K having a 383 stroker built along with the trans and nice do-dads that go along with it. The shop that did it put a cheap electric fan with a controller that just sticks in the cooling fins of the radiator. :shock: He fights cooling issues I have no pity for him are the shop. Right there lye his problem neither he are the shop get it.

It sounds good looks good and chits and gets he should have dropped some of those chrome do-dads and brought a electric fan that fits the rad fits like a glove and runs off a coolant switch that fits in the intake manifold. But that would take some engineering and moe money :wink:

Geo-TH,In · May 13, 2017

JD,
I heard of electric steering on cars, just didn't know which ones.

I want to thank you for suggesting short-sticking. I use it all the time, except when I'm on an incline. Each time I short stick I think of your advice. I also use it to re-positioning the rear sideways. So thanks for you advice of short sticking. I never would have thunk of it.
geo

John T · May 13, 2017

I sure do George. At high speeds in a vehicle the moving air is already forcing enough air through the radiator so you don't need to waste engine HP to turn a fan, belt or electric. In addition, temperature can also regulate how much fan is needed.

Hope to see you and Wilson this fall at Elnora???

John T

Hobo,NC · May 13, 2017

(quoted from post at 18:11:19 05/13/17) I sure do George. At high speeds in a vehicle the moving air is already forcing enough air through the radiator so you don't need to waste engine HP to turn a fan, belt or electric. In addition, temperature can also regulate how much fan is needed.

Hope to see you and Wilson this fall at Elnora???

John T

That's if all the original air deflectors, seals are what ever duct work that was installed on it when it left the factory.

Reminds me of a 80's Pontiac Trans am it does not have a grill opening its totally dependent on a air deflector under the car to scoop up air and rout it to the rad. If it got knocked off took off its gonna heat electric fan are not.

John B. · May 13, 2017

A belt driven fan puts a tremendous load on the engine. Just watch the tach on a Semi that has an air clutch on the fan, when the fan kicks in watch the RPM's drop. I've seen more vehicles overheat with electric fans than those with belt driven fans. With electric fans relays go bad and the fan doesn't work. With the front wheel drive cars now that have the engine in sideways they all have electric fans. The load the alternator puts on the engine is much more extreme but is not a constant load as a belt driven fan.

RayP(MI) · May 13, 2017

We had a irrigation pump powered by a Willeys industrial engine, back in the '50s. (Basically a 4 cylinder Jeep engine.) When we would shut down, the back surge of water would twist the frame, and rupture the radiator. Manufacturer replaced radiator with a heat exchanger which used a stream of water out of the irrigation pump through a coil of tubing in a metal box to cool engine. They took cooling fan off, and threw it away. Ran pump for one setting, and it was so hot without air flow, that you literally couldn't touch the tires on the frame. Fan came back before next run.

Dean · May 13, 2017

It will take a good dyno operator using a good dyno to notice any HP improvement.

Dean

Dean · May 13, 2017

Yes. Delco made them in Dayton.

The viscosity of the silicone oil in the unit changed with temperature reducing (but not eliminating) the engine load.

Hot rodders would remove them and replace with whatever to gain a bit more HP at high RPM at the expense of inadequate cooling at low RPM, high ambient, AC, etc.

Dean

Dean · May 13, 2017

Indeed, Brendon.

Such units can also occasionally reverse at high speed to help clean debris from the radiator.

Commonly done on fork lifts, etc.

Dean

buickanddeere · May 13, 2017

For a parade or show tractor that is missing shutters or a thermostat. An electric fan would keep the coolant at an ideal 195-210F to reduce carboning .

Roger in Iowa · May 13, 2017

What is short sticking???

kencombs · May 13, 2017

JohnT is right of course, with these additions/exceptions. While the engine driven fan is drawing HP all the time, the electric only runs as needed. So, during light load use, cool/cold weather there is a potential for hp/fuel savings.

I suspect, but have no data to support, that the combination of a water thermostat flow control and no airflow when cold may speed warmup. that's especially possible in those cases where there is a thermostat bypass that allows partial flow even when closed. That would allow the engine to get up to it's most efficient operating temp quicker.

all the above presumes the electric fan is properly engineered with water temp sensing control.

kencombs · May 13, 2017

Yeah, and the flex blade fans that flattened their pitch under high speed loads. The came with spring steel or fiberglass blades riveted to a thicker center hub.

I've seen a couple of hoods 'ventilated' when the steel versions fatigued!

Deutz Lover · May 13, 2017

For three or more years our Tacoma has had annoying engine vibrations. I went through all of the fault procedures including getting a new harmonic balancer. As I was removing the fan blades and thermostatic unit I found that the rear bearings were gone causing the viscous disk to wander. It could have been from a vehicle lightning strike. I replaced it with an electric fan and the worst vibrations went away.

John T · May 13, 2017

Ken, EXCELLENT and obviously correct point you raise........

"While the engine driven fan is drawing HP all the time, the electric only runs as needed."

I guess the mechanical analogy would be the use of fan clutches, maybe temperature or RPM regulated????

John T

dlbuck · May 13, 2017

Geo-TH,In My 2016 Ford F150 has electric power steering. I really like it. Steers easier than my F450 work truck.

sotxbill · May 13, 2017

(quoted from post at 23:04:58 05/12/17) Heard some tales of people swapping out belt driven fans on older cars and adding electric thermo fans, said they gain some more HP and is more efficient for the engine.
What's the hearsay on tractors ?

Most new cars come with elect' fans... as the engine is turned sideways...

And electric fans only take energy when needed, not all the time,, and then lots of cars come with two fans, side by side,, one will kick in and the second as/when needed... But is your in a hot climate, running a/c, both fans will run all the time. electric fans can save on fuel as they run only when needed and give better control of the temp...

And electric power steering has been around for some time now as it does NOT load the engine with the loss of a pump, and only draws power when your turning, so again, it contributes to fuel economy.

notjustair · May 14, 2017

I asked someone back when I drove school bus about this. I was interested in changing my first bus over to electric. It had a 370 gas and the fan would really kick the engine down. I was told that over 35 mph the fan is secondary to the wind generated by the speed. Then I took that bus on a 17 hour trip at 70 mph. The fan clutch kicked in all day long. That's when I realized for something like a bus I would need a HUGE electric fan to make up for the clutch driven belt fan. I kept her like she was and learned to listen for the roar when it was hot out.

Still my favorite bus ever.

Geo-TH,In · May 14, 2017

Man's problem.

Good and bad of having a Thermo fan instead of belt driven?

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