73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Projects Posts (NOT VEHICLES) => Topic started by: cb7501 on September 13, 2008, 12:25:37 pm
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After seeing cruzinhighs dual fan setup (nice!) I thought I would post what I did...
Here is how I did an electric fan installation on my 1984 GMC ½ ton:
The fan came from a ‘98 mustang V6 (used $30).
I used a fan controller from Autozone, part 733652, $25. It included a fixed (set temperature) thermostat switch, wiring harness with relay, and fuse. You can also buy a different controller with an adjustable thermostat switch that will let you dial in the temp. that the fan comes on, if you prefer. Some fans may require a heavier duty relay than this 30amp setup, be sure you use the correct relay if you use a more powerful fan…if you try to ‘make it work for now’ with the wrong relay you’ll burn it up and be out of commission!
I spent around $10 additional in wire, connectors, etc. Grand total: $65
This is an easy project. I have pretty limited mechanical/electrical skills, and I had zero problems. The hardest part by far is figuring out how to setup the wiring, and if you buy the above controller kit you bypass that step! You could even buy the above controller and replace the 30 amp relay with a larger one if you don’t want to do the wiring and need a bigger relay.
1.) Remove stock fan shroud, remove 4 nuts from in front of stock fan. Remove fan and replace nuts. (You
may need to bump the fan with a mallet to free it).
2.) I ran power to the thermostat switch from the wiper motor. This way the fan can run whenever the
key is 'on', and will not remain running after your leave your car. Install the thermostat switch
between fins near the upper right hand corner of the radiator (as you face the grill), close to where
the coolant hose comes in.
3.) If you have A/C, there is a wire to hook up to the A/C clutch so that the fan will run whenever you
have the A/C on. There is also a wire provided so that you can turn the fan on/off with a toggle
switch if desired.
4.) I ran the fan to the truck battery, and a fuse, using the fan controller wiring.
5.) Mount the new fan to the radiator, I used machine screws through existing holes in the fan shroud and
drilled into the top and bottom of the radiator, you can also buy mounts that pull through the radiator
fins if you don’t want to drill.
I had to cut some plastic off behind the electric fan motor to clear the water pump
pulley. (If you bought a used fan and haven’t checked to be sure it runs, do so
before mounting it)
6.) Run a ground from the relay, and one from the fan, to bare metal. Run the correct
wire to the fan motor form the wire harness.
7.) I recommend using male and female connectors or wire nuts instead of soldering for
connections. That way you can remove components without cutting wires if need
be later.
8.) Fire up the engine and let run, watching your temp gauge to be sure that the fan
kicks in before things get too hot. If the fan doesn’t kick on it’s time to get out the
voltmeter and play detective.
http://www.fordmuscle.com/archives/2003/02/electricfan/ - this is the link that made me pull the trigger on this project. They did the swap on a 5.0 L mustang that they race.
If you google “junkyard electric fan swap” or “e-fan installation” you’ll get more advice & good reading material than you can shake a stick at. Most failures seem to be from starting out with too small of a relay with high powered motors. There are many excellent new kits available from folks like Permacool, they’re just too rich for my blood $$$…
I felt a definite difference in engine response without a doubt. My truck has the 250 straight 6, and I got my best mileage ever after doing this project, 21.4 mpg. Before doing the e-fan my mileage ranged from 14-19 mpg, and after it has been 18-21. Not a huge difference, and I won’t claim for sure that it’s all from the fan (for instance I also put in synthetic diff. lube around the same time). But for $65 and a few hours of work, why not give it a shot?
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nice info. Maybe Chris can put this in the Technical Pages for future reference.
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If there are no more questions and comments I can move it.
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CB7501
That looks great. I can hardly wait to get that project rolling on my 77. I am going to make a few calls tomorrow to some salvage yards and try and locate a fan. I am inspired. An even if it only resulted in 1 or 2 mpg difference, at $3.65 a gallon, that's huge.
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A fella I work with tell me that the Alternator will have to work so much harder due to the amp draw from the electric fan, that my mpg and power gain will probably be completely offset. I see where he is coming from but don't toatally agree. Did you upgrade to a larger alternator?
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If you've ever seen a full load test for an alternator, you'll know. Back when all the alternators were 40-60A, they used 5hp motors to drive them for the test, and the draw was amazing.
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Most cooling fans pull about 20A when they're on which is not all of the time obviously. If you were to do this I would upgrade to a 90A generator.
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Yeah, like Vile said, it would probably be wise to swap in a 90 amp alternator. My stock unit is a 66 amp that came with the 'cold climate' package my truck was ordered with and I haven't had any issues yet...but my truck has no a/c, very basic radio, no air pump, etc. My ammeter is almost always just below the red on the right (high) side of the gauge while I'm driving, and dips a little when the fan comes on. But most people who put in an electric fan in do upgrade, and I probably will too when I get a chance.
Jason
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Yes, what has to be considered is the amount of time the elec. fan is on. The mechanical fan is providing drag all the time. The fan clutch may not be engaged but there is still drag that is present at all times. The e-fan only presents load when it is operating. And, in cooler climates it might not even have to operate if there is sufficient cool air flowing through the rad.
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Nice job Jason!
Great upgrade too for that kind of budget huh? I think this is a fun project that almost any of us can tackle easily with the vast amount of parts that you can get your hands on even in the junkyard nowadays.
I still haven't upgraded my alternator either, but assume that as was pointed out here it would be a wise consideration.
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I know this is old, but what size is the fan you installed? 14"? 16"?
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I know this is old, but what size is the fan you installed? 14"? 16"?
Personally with trucks our size, even with a Standard Cab Swb, I would run no less than 16" for a single fan setup, or 14" with a dual....
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A 16" fan thermostatically controlled with a shroud should be just fine. I am building one right now. My sheet metal buddy picked it up yesterday so he can fab the shroud for me. He smokes so much mary jane it'll be interesting to see how good he does lol. He told me it would be done by this weekend. My other buddy is picking me up a 3'x3' piece of stainless and I plan on building another one anyway if this one doesn't come out good.
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Good luck getting it back by this weekend. If there's one thing potheads don't have, it's a sense of time.
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I just installed the relay and thermostat so I hope it comes out good!
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I did this. I've got one 16" and one 14" and have upgraded to a 94 Amp alternator off a Chevy Van, cause the stock 78 Amp one was not enough at night to keep the haedlights from dimming with the fan on, which is just wired into an on/off switch (which has been forgotten to be switched on when driving a couple times, but never overheated it yet).
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Wire up a thermostatic control. You can get one for around $30 bucks at autozone. It's adjustable and comes with the relay and circuit protection.
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What brackets did you use to hold the radiator in place? I have an 81 Chevy and the stock ones don't look like that? -Thanks
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If you are referring to the original post in this thread from 2008 he may not respond but those are the stock 6 cylinder radiator mounts for 81 up rad support