i have the extra mechanical fan that comes with the tow package. it ONLY comes on during engine startup when it is cold (of course) and on those very hot summer days while i am towing. i was thinking of removing it for september through may for gas mileage saving, because it is obviously robbing power having it there, and it never turns on 9 months out of the year. has anyone tried this, and did they notice a MPG bump because of it? or am i wasting my time?

 

Your taking off the electric fan and keeping the engine driven mechanical fan?
Is that what your trying to say?

Lose the mechanical and keep the electric.
Then you'll see a mpg increase.

 

Is that sufficient for cooling? I thought you'd replace the mechanical with another electric?

 

I ran one fall and winter WITHOUT a fan because my fan clutch was always engaged. I got a new one before spring came around, but I never had one ounce of trouble with high temps. I'm sure you could never get away with that in the summer, especially around here where triple digit temps are the norm, but if I could drive around without a fan at all I'm sure you'd probably be fine with just the electric one.

Now I did always keep the fan and clutch in the back of the truck so i could put it on if the temps were ever to climb so i could would also recommend that you do that as well, just in case. the mechanical fan is really easy to put on, you just thread it back in place and tighten it up hand tight and it will tighten the rest of the way once the engine starts running.

As far as MPG gain, maybe I saw up to 1 MPG, but nothing significant, and that was going from having my fan stuck on all the time to having no fan at all. The possible small MPG gains are totally not worth the risk to your motor if you undercool it. I did notice that I cold rev the motor up quicker without it though, but again, the gains were nothing that was going to turn my truck into a NASCAR truck. I can't remember my exact numbers, but I think it gave me an extra 1/2 second on 0-60 times. Again my fan was not working, it was totally stuck on so you wouldn't see even that much difference if your fan clutch is working at all.

 

no, not at all. i'm saying leave the Efan, remove the Mech fan. and this is only for september through may, i'd put the mech fan back on every spring for the hot months.

 

Lets just say that there is a proper way to set up electric fans and using the correct fan for the job.
I ran dual fans from an Aerostar on my 79 Ramcharger.
Built 360/727 with Dana 60's and 40" Swampers.
Only time my fans ever came on was in slow traffic or stopped at a light.
Even when pulling a camper on the hwy the fan never came on.
If you do have a heating issue then your just not set up right.
I ran a 195 thermostat and had my fan come on at 210.
You could watch the temperature gauge drop when it came on. Worked extremely well.
By losing the mechanical fan you do gain some mpg and free up some HP.
Maybe not much but it is noticeable.

 

when gas is $4 a gallon...a 1 mpg gain sounds GREAT! (i'm not looking to get 40 mpgs, hahaha, but 17 would be nice!)

 

Making the change will net you almost nothing and put your Dakota in danger of overheating is that worth it?


You need a car like a Honda or Toyota for what you want mpg trucks are gas hogs.

 

the 4.7 is a notoriously bad engine to overheat ever you do not want to find that out first hand... not a good idea.

 

well, i'm not concerned with it overheating during september through may. i can easily hear the mech fan turn on, and over the 4 years i've had it, it only turns on during engine start and while towing on hot days. i would reinstall it during summer so it would be present for the time it would be needed.

i've been down the toyota route multiple times, and i've also been down the honda route, never again. all american vehicles from this point forward! i'm fine with less than 20mpgs, but it can't hurt to try to get one more mpg!