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bennelson 03-17-2008 08:10 PM

S10 radiator fan changes?
Does anyone have first-hand experience with removing or disabling a belt-driven radiator fan?

My 4 cylinder 5 speed manual Chevy S10 truck is only getting about 24 mpg.

I put a can of Seafoam through the gas tank and have a new fuel filter, but need to let the penetrating oil work on the rusty fuel lines before installing it.

My tires are pumped to 45 psi and my radio antenae is removed because the radio doesn't work anyhow.

I noticed that the serpertine belt is pretty worn and should be replaced soon. That belt runs the water pump, fan, power steering, radiator fan, and alternator.

If I am replacing the belt anyways, can someone suggest what I might want to get off it to improve fuel economy?

It seems like the radiator fan shouldn't be that hard to remove. I have also heard of removing or "turning off" the alternator.

Any tips for the power steering?

Please help me get started with the easy things first here, I would really like to hit 30 mpg with this truck.

I do have a new air filter in there. I haven't looked at the spark plugs yet. Would new plugs and wires help with fuel economy?

I bought this truck in January and really haven't worked on it yet at all.

If I can get the fuel economy on it up, then I can sell my beater Dodge Shadow and drive the electric Metro on short trips and the S10 for longer hauls.


PS - I would eventually like to do a lightweigt "aerocap" for the truck as well.

bennelson 03-17-2008 08:37 PM

Frank, did you just put a shorter belt on? Or did you do something else to it?

bennelson 03-17-2008 09:33 PM

So you remove the fan blade from the pulley, that way the pulley still spins and you still use the same length belt?

You get better fuel economy because there is less resistance from not having the fan pushing the air?

brucepick 03-17-2008 10:51 PM
See all that nice extra working room available with electric fan instead of clutch fan??


Originally Posted by bennelson (Post 14760)
So you remove the fan blade from the pulley, that way the pulley still spins and you still use the same length belt?

Yup. On my car there were four studs mounted on front of water pump. Pulley was slid on first, and the fan clutch base was slid on in front of that. Remove the four small nuts holding fan base onto the pulley and it comes off. Put the nuts back on to hold the pulley onto front of pump. One stud worked loose from the end of pump shaft. Bit of a pain getting it all back together again. So be gentle on the nuts when you loosen. Of course your GM thing might be a bit different but I'm sure the basic idea is the same.


Originally Posted by bennelson (Post 14760)
You get better fuel economy because there is less resistance from not having the fan pushing the air?

Exactly. True that there's a temperature-driven clutch between the fan and it's drive pulley. But you can see that it spins all the time, just spins faster when things get hot. So your mpg or power gain comes from not having to spin it and push air all the time.

I found that on open roads with oem grill, I was fine under any conditions even in the hottest weather. Anything 30 mph and up was fine due to the airflow over the radiator. Idling, stop and go traffic will need an electric fan or something to provide cooling. It's possible to drive without that need if you can kill the engine when in those situations. Any regular traffic light, I think you can get by without a fan because you're not stopped very long.

With a grill block you might find it getting warmer more often. At about 65 deg. with the grill panel you see in my avatar, the fan did come on when on any kind of mild upgrade Interstate. Downhill it would cool off and the fan would switch off. That opening is only about 70 sq. inches, about half the stock grill opening area. I'm currently making a new one with 100 sq. inches opening for warm weather use.

MetroMPG 03-18-2008 11:05 AM

Ben: you've got an extra electric radiator fan (with a shroud) you just yanked out of the Metro. Use it in the truck.

EDIT: and if you're going to be doing mostly highway with the truck, you'll definitely have to lose the square cap to get good mileage.

bennelson 03-18-2008 11:52 AM


Originally Posted by MetroMPG (Post 14833)
Ben: you've got an extra electric radiator fan (with a shroud) you just yanked out of the Metro. Use it in the truck.

EDIT: and if you're going to be doing mostly highway with the truck, you'll definitely have to lose the square cap to get good mileage.

I was exactly thinking about using the Metro fan in the truck!!!!!!

I need the cap for now for my work. I have equipment that I need to move around that I can't let getting rained on .

I plan to do an aerocap once the weather is a little nicer and I have some time to work on it, then I can sell the green cap. (it is a little heavy!)

bennelson 03-18-2008 08:25 PM

I noticed that there is a big cover over/above the radiator that appears to be the intake for the combustion air.

Is that so the air is warmer going into the engine? (warmed by the heat of the radiator?)

I thought I heard that cold air combustion burns cleaner = less pollution.

What temperature is best for fuel economy?

Since I have to move this cover to get at and disconnect the belt-driven fan, should I do anything with the air intake while I am at it?

suchy21 03-26-2008 04:11 AM

My first ecomod was swapping out belt-driven fan for an electric fan in my Ranger. Not sure yet on the FE changes, but the engine (and thus cabin) heats up more quickly in the winter. Also, cab noise is noticeably lower.

How-to articles for the fan swap in a Ranger, presumably similar to the S10:

My 16" Proform Electric Fan:

bennelson 04-06-2008 01:23 AM

Hey everyone,

I finally got to working on ecomodding the S10.

There is a big cover over the fan. I removed that and got a look underneith.

This truck has kinda a big funnel to make all the air going through the radiator get sucked through past the fan.

I removed the mechanical fan. After starting the truck up, the first thing I heard was the noise of something falling off, immediately followed by the serpentine belt.

Turns out the nuts that hold the fan on also hold on the pulley the belt runs around.

I put the pulley back on with the nuts and a couple of washers to space them out (threads didn't run all the way down)

I did a zero carbon run over to the auto parts store and picked up a new serpentine belt. The old one wasn't broken, but looked like it must have been the original belt on the truck.

Figured if I have everything apart under the hood, I should at least replace that belt.

I pulled the electric fan off the Metro's radiator.
I put it in the S1o right against the radiator and zip-tied the top of it, then drilled a hole through a plastic part on the bottom of the fan frame and put a long screw through it to hold it on the bottom.

Now I need to figure out how to wire up the fan. It has two wires on it. I noticed that reversing the power leads reverses the fan direction.

I will need to make sure I get the suck/blow thing right on this. Radiator fans suck, right? Air goes through the radiator from the wind and driving fast. Fan should also suck so air is going IN through the radiator. Do I have that right? Just don't want to screw up and fry my engine!

What's the best way to power the fan? The truck has very few accessories - no airconditioning.

Should I run a wire through the firewall to a high amp DC switch I can install in the dashboard? Otherwise, I could put a relay in and use a lower power switch. Would be the first time I have done anything with relays, but I think I can figure it out.

Any other way to wire this up? Thoughts?
Mechanical Fan removed - still old belt
Geo Metro Radiator and Fan
Geo Metro fan installed with zip-ties and a screw.

suchy21 04-06-2008 10:44 AM

Rad Fan
Yes, you want this electric fan (as it will be your primary cooling fan) to be a "puller".

To power the fan, I would suggest buying a temperature-controlled relay like
(You'll probably have to enter your zip code to see the part). This relay has a temperature-sensing probe that activates the relay to switch your fan on above a certain temperature, which is the advantage of an electric fan. If you were to run the fan constantly, you would be better off with the belt-driven fan.

Another option (cheaper, but not as automatic) is to wire up your proposed switch in the cabin so that you can manually switch the fan on and off. If you monitor your coolant temperature gauge while driving, you can manually switch the fan on when it is getting hot.

Whichever option you choose, I would suggest the following electrical connections:
+ terminal: Ignition-controlled positive (like an unused slot in the fuse box?)
- terminal: Body ground

Also, if you have any issues with the attachment, there are specialty zip ties with pads for aftermarket electric fans that thread through the fins in the radiator to create a more secure attachment.

One potential problem I see with your fan is that, being from a Metro, it looks to be smaller (diameter) than the stock S-10 fan. Is that the case? If so, this could result in inadequate cooling abilities, as the fan does not force airflow over the entire face of the radiator. Just something to monitor once you start driving it.

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