Hey ladies and gents, you've helped in the past, so I go to you again.

I just ordered a 16" electric fan for my '04 4.7. How much cooling improvement should I "expect"? I'm also about to put on a high-flow muffler/pipe that'll really help my CAI breath better. But the fan was something I saw here and there, and my 4.7 gets pretty warm towing up hills. With the added power of the CAI and the exhaust, I expect to run slightly cooler, but I still wanted to help it out.

Any advice/experience with the electric fans?

I'd be worried that a single 16in isn't enough airflow, especially for towing. I converted my old 92 GMC Sierra (5.7 liter) to electric fans and used two 14in fans. It was fine in typical 90-100 degree Georgia weather even when towing 6000+ lbs (Grand Marquis on U-Haul trailer).

Isn't there just a single fan of similar size attached to the engine on the 4.7? I think the only thing you would notice would be minimal... you wouldn't have the extradrag put on the engine... I doubt it will run any cooler

That's what I was wondering. The fan I ordered has a higher flow...that's what I've read about the aftermarket fans. More flow.


John M, were you running two 14" side by side? Or one pushing and one pulling? Just curious. I've read about running a push/pull combo as well.

*EDIT* What concerns are there with removing the stock fan? I don't have to worry about any weird balancing issues do I? How much of that stock spinner (if that's what you call it) should I leave there? The fan looks like it just unbolts easily enough, but there is a 3-4 inch hex-shaped spinner that will still be there. It may/may not get in the way of installing the electric fan. That's if I go through with the install after all.

old posts that might be of interest:
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April 27, 2001
Following up on the air dam on/off MPG tests I did on Monday the 23rd,
today I did a MPG test run at a cruise-controlled 70 mph over the same stretch
of Interstate 40 without my radiator fan.

I filled up at the same gas station, set the air conditioning the same, and
the weather was nearly the same - 70-79 degrees. Today there was a 10-15 mph
wind coming from the west (more on that later).

The truck was about 4 lbs heavier because I was carrying the big 1 7/16 inch
wrench, hammer, and small 1/2 inch flare wrench I used to remove the fan
bolts.

By the Exxon gas pump I used 11.105 gallons of 87 octane.
By my (corrected) truck's odometer I went 218.5 miles.

MPG at 70 mph without the radiator fan was 19.68
Compared to 18.94 MPG on Monday's test with fan,
this represents about a 3.8% gain.

The Oztrip meter results from measuring fuel injector on-time were similar,
showing a consumption of 11.6 gallons over 218.7 miles
for a fan-less mpg of 19.34
On Monday with the fan the Oztrip had showed 18.86 mpg, or a gain of 2.5%

When I first started this test run at about 10 am, the Oztrip meter showed
surprisingly good MPG - about 20 - so I had high hopes for what fan removal
was going to do.

Unfortunately, I found that part of the gain on the southeast bound leg of the
trip was due to the 10-15 mph winds at my back.

When I turned around at Wilmington NC and headed back, the average mpg
steadily dropped as I now drove against a head wind. Looking at the Oztrip
trip computer numbers it seems I averaged 19.96 on the southeast bound drive
with the favorable tailwind, and 18.7 driving northwest with the unfavorable
headwind. This was the 1st time I had bothered to watch for what winds do to
mpg. Looks like they can raise/lower mpg by 1.6 even at a "calm" 10-15 mph
level.

As to the temperature of the coolant without the fan - it stayed very steady
at 180 degrees during the MPG test run even with the air conditioner on.

When I slowed to a stop at the end of the trip while turning back into the gas
station, the temp gauge indicated a momentary rise to about 195.

I actually took the fan off late yesterday afternoon and drove around without
it to experiment. As long as the truck kept moving the temp gauge stayed at
180. I parked the truck and let it idle for about 10 minutes. This raised
the temp gauge to about 210-220. I then put on the heater full blast to see
if this would lower the temperature back to 180. It did not - the temp stayed
the same and neither fell nor raised any more. I then drove the truck again.
Within 1 mile the temp had dropped to 200 and within another mile it was back
at 180 degrees F.

The fan on a 5.9V8 Magnum is kind of funky looking. It has 5 blades, but 2 of
them are bunched together and the other 3 are spaced out normally. There is a
stiffening wire embedded in the blades. It takes less than 15 minutes to take
this fan off, but if the fan had been made in two parts that split - you would
not have to take the big nut off the fan clutch - and the fan could be removed
in 5 minutes.

Instead of buying a 36 mm wrench {1.417 inches}, I cut two strips of metal
from a tin can. These strips turned out to be 0.010 inches thick. I taped
two such home-made 'shims' to the inside faces of my 1 7/16 wrench {1.4375}
which closed the opening up to 1.4375 - 0.020 = 1.4175 This worked fine to
loosen the clutch-to-waterpump nut. Make the shims 'fish hook' shaped and you
can tape them in place from the backside.

I may try to drive without the fan in city driving a bit to see what happens,
but I am carrying it with me just in case I have trouble.

I still have the Evan Cooling 'waterless' NPG coolant in my engine. This
won't boil over until 370 degrees so I have some safety factor that a normal
antifreeze would not have.

=========
: John_N writes:

>Hank,
>I found better results when I installed the electric fan on my Dakota. Mag
>whereas you have the 5.9. My fan is of different configuration that yours
too. >Instead of the 7 blade fan you have, or the 5 blade fan shown in the
Dodge >ad's. I have a monstrous fan with 9 equally spaced blades. It must
weigh 15 >lbs including the clutch. My mileage went from 14.8 to 16.4, not
cruise >controlled, My highway mileage change equates to a 9.2% increase
without >the fan. John

John,
It makes sense to me that a Dakota might have a bigger gain from not using the
fan.

If a Ram uses 60-70 horsepower to cruise at 70 mph, a smaller, lighter Dakota
might use only 45-55 hp. Since the fan wastes about the same same in either
case, the Dakota mpg would go up more.

It is interesting to hear of your bigger 9 blade/heavy fan. Would this be a
'towing package' option that we have not noticed before ?

How much horsepower does the stock fan waste ?
Here's a ballpark guess -

The gaspump said I saved .425 gallons.
The Oztrip meter said I saved .28 gal
The average is .35 gallons.

This .35 gallons was saved over about a 3.1 hour trip,
or about .35/3.1 = .11 gallons per hour.

A gallon of Exxon 87 octane weighs 6.16 lbs per gallon.
So I saved .11 gal x 6.16 lbs/gal = .70 lbs gasoline per hour

A rough rule of thumb is that on average a engine will use between 0.40 and
0.65 pounds of gasoline for each horsepower that is generates per hour it
runs. This is called by engineers the "Brake Specific Fuel Consumption", or
BSFC.

Picking 0.55 lbs fuel/hp-hr as a part-throttle average -

.70 lbs fuel/hr divided by 0.55 lbs fuel/hp-hr = 1.2 horsepower for the fan
======
"Jeff T" writes about:

>It would seem to me that the greatest benefit would be seen in "city" driving
>where all the cooling is achieved via fan operation. In fact, I would
estimate >that a good 70-80 percent of a fans "work" is performed at speeds
under >50mph. opinions on it.......?

Jeff, I have only done one quick test in the city.
On a drive I do every morning of 11.3 miles from a dead cold engine start, I
usually get 13.8 to 14.3 MPG.

On Saturday morning I recorded the Oztrip computer readout of miles and
gallons, then went on the 11.3 mile trip. I got 15.4 MPG according to the
Oztrip.

Thanks HankL... that's good info. I think I'll install it and see what happens. I'll report back here when I do. It's supposed to be delivered next Monday.

If memory serves me
the 4.7 V8 viscous clutch fan is already very high slip
and probably uses less hp in the 1500-2500 rpm range
than a 5.9V8 viscous clutch fan.

I ran them side by side. Conveniently my radiator was 28 inches across so it worked out nicely.

Electric fans move nowhere near the volume of air that an engine-mounted fan of the same diameter does. That means you need more fan to get the same amount of cooling. I was very glad I did that mod on that truck and I hope to do the same on this one soon. I'm also interested in increasing the airflow through the AC condensor so it'll stay colder at idle.

Is that clutch thermostatically controlled? If so, is that an external thermo that can be hooked to the elec. fan? 12V etc?

Whew...