Removing clutch driven secondary fan (for mpg) - Jeep Commander Forums: Jeep Commander Forum
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post #1 of 7 (permalink) Old 03-31-2011, 03:24 PM Thread Starter
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Removing clutch driven secondary fan (for mpg)

Im planning to remove the secondary fan that came with the tow package. Im aint towing anything atm and like any belt driven accessory it must burn some HP from the 4,7. In hope it will help a little on the fuel economy.

Anyone here already had the same idea?

Thanks
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post #2 of 7 (permalink) Old 03-31-2011, 03:28 PM
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I really don't think you will have enough of a gain, if any, to make it worthwhile. Probably not even enough to measure.

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post #3 of 7 (permalink) Old 03-31-2011, 03:35 PM
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They're easy enough to remove and install (if you have the tool) so I say go for it. When those clutches go bad they're a performance and MPG hog. If the clutch is functioning properly you probably wont see a big improvement. ... but it couldn't hurt.
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post #4 of 7 (permalink) Old 03-31-2011, 03:46 PM
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Quote:
Originally Posted by RS25 View Post
Im planning to remove the secondary fan that came with the tow package. Im aint towing anything atm and like any belt driven accessory it must burn some HP from the 4,7. In hope it will help a little on the fuel economy.

Anyone here already had the same idea?

Thanks
Gains in fuel economy can be had, but are very, very minor and only seen on the highway. You can remove accessory belt driven fans and in the future if you wanna go back, you can always install an electric fan on a thermal switch. I completely removed the fan on my 2000 XJ, installed a 180 degree thermostat then wired a thermal switch (which allows you to adjust the fan on/off temp) to a 14" Black Magic fan. I also wired the switch into the existing air conditioning fan so both run when temp. goes over 185 degrees. This modification is an old drag racers technique to reduce parasitic drag on an engine (allowing for a bit more horsepower gain, likely somewhere between 5-15 hp. depending on size of the engine). The nicest thing about this type of modification is the fact that the less reciprocating mass on the front of your engine the longer the bearing life will be in other things like alternators and water pumps. Another side benefit is it allows an engine to rev. faster (by a very small amount). Just an idea for you to mull over. If you do decide to do this, and aren't very familiar with wiring into electrical systems then find a friend or a professional mechanic to help you with this type of project.

Last edited by CommandSystemsGo!; 03-31-2011 at 03:52 PM.
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post #5 of 7 (permalink) Old 04-02-2011, 08:46 AM Thread Starter
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Thanks for your inputs.
I will try to make a tool out of a steel plate to lock the water pump.
Should be out easily with it.

I won't do any other change to the cooling system atm. Still under warranty.
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post #6 of 7 (permalink) Old 04-02-2011, 09:08 AM
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Frankly, I see no advantage to this.
If the fan clutch is working properly, it essentially freewheels with no load transfer to the belt.
If it is operating as designed, the clutch should only fully engage the fan when the air passing across it is at a pre determined point. That would be to prevent overheating, naturally.

At speed, the air passing through the radiator actually speeds the fan blade up a bit, virtually eliminating any measurable parasitic drag.

My thoughts are also guided by and old mechanic saying 'Don't try too hard to out engineer an engineer'

If there was any mileage to be had by removing this somewhat expensive component and running two part time electric fans, it would have been done.

My opinion,
Rob
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post #7 of 7 (permalink) Old 04-02-2011, 09:33 AM
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A lot of companies have gone to E-fans for improved efficiency. There are some parasitic losses.

Granted I wasn't aware that the tow package with the 4.7 added a "secondary" clutch fan... if it is truly an option only to aid while towing, then it doesn't hurt to take it off. R&R is about 15 minutes.

If it helps anywhere, it will be city MPG. Here the clutch will engage but the efans will still do most of the work if you're sitting idling at lights.
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