wiring harness for electric fan

[chris1htx]

hello all,

i'm looking to install an electric fan but wanted the fan to turn on whenever the truck is turned on. would i need a wiring harness for that or would i just directly wire to the battery?

[chris1htx]

i meant to the ignition switch not battery

[school boy]

You could use a heavy duty relay and use a ignition on only hot to turn on the relay.

[Just call me Sean]

You will have to use a relay no matter how you trigger it.

[piecesparts]

Use a relay that is tied to the battery. Make sure it is heavy duty enough for the fan. Tie the trigger for the relay to an ignition "ON" contact point. Be sure to use fuses or circuit breakers on the wiring and especially BEFORE the wire passes through any metal bulkheads.

[gmachinz]

If you are going to wire your fan always on with key on, you are going to drastically shorten the lifespan of that fan motor and control relay(s). Is there any reason you are against using a dedicated temp switch to activate the fan via a relay?

[MountainGoat1966]

What they said.
PLUS, don't use those plastic strips that run through the radiator core.
Eventually you will end up with at the least a repair job, worst case replace the radiator.
Ask me how I know this.
Do a solid mount to the core support.

[chris1htx]

the reason i wanted to have the fan always on was to avoid the truck from ever overheating. but i guess with the right temperature control you can avoid that.

[gmachinz]

Being in Texas I can understand that concern! However, you want to add an electric fan safely and efficiently. I would suggest whatever fan or dual fans you decide on, remember that nothing is free-if you want to pull a lot of heat out quickly, you need a powerful fan. To reliably run a powerful fan, you need to make sure your charging system is up to the task. These issues become more obvious if you we running a BB, and/or AC, etc.
These trucks offer little in terms of proper shrouding and there is no air movement other than through the grill opening.

Its my personal experience on this but I prefer OEM style fans over aftermarket...one reason is I don't care for the aftermarket "heatsoak" aluminum shrouds as I call them-plastic HD shrouds don't retain heat like that. And, the OEM fans always have more CFM capability and reliability. The majority of my experience is with the Motorcraft line of fans but the devil is in the details and instead of explaining blade shapes, contours and shroud/motor design, suffice it to say I think the aftermarket sells mostly inferior quality fans.

Just research some various fan schematics and decide on what you feel comfortable with making-BUT my advice is to first decide on the biggest possible fan you can fit and go from there. You can always tune down a powerful fan but you can't do crap with a weak fan to begin with.

[rich weyand]

Originally Posted by chris1htx

the reason i wanted to have the fan always on was to avoid the truck from ever overheating. but i guess with the right temperature control you can avoid that.

Yep. The big advantage of an electric fan is that it does not run when you don't need it, freeing up engine power. It also gets you better temperature control, especially when it is very cold, but you probably don't need that bit in Houston.

Here's what I did, and it worked out really well. Complete instructions, originally posted on another forum. Worked out really well. In six months now in hot and cold weather with no problems. Hardly ever turns on except when sitting and idling.

I have been researching going the electric fan route. The engine has a heck of a time warming up in the winter. Most people don't know, but the thermostat never shuts off completely. There is a bypass hole that lets some water flow all the time. The water going into the engine from the radiator in the winter is stone cold. Cold engines don't run as well, and get worse gas mileage.

Of course, the other issues apply as well. I prefer not having the shroud and fan and all, both because it makes the engine harder and more dangerous to work on and because it's not as pretty as having it gone. Not running the mechanical fan all the time saves gas mileage, frees up some power and torque, and takes a load off the water pump bearings. It also keeps water and such that gets splashed into the radiator from getting distributed all over the engine and engine compartment.

After much poking around, I went with a pusher, no shroud. Yes, yes, I know, but I don't tow, I don't plow, I don't go rock crawling, and I don't drive in the mountains or the desert. I don't even sit in stop and go traffic. Mostly I'm moving, and you don't need any fan when you have ram air through the radiator.

I selected the Flex-a-lite 398, and flipped the blade over for pusher mode. This fan is 16", which fills the core hole in the bulkhead top to bottom. It delivers a real 2500 cfm (read reviews carefully; there are some fans out there that, um, over-spec, shall we say). I used the Flex-a-lite 31149 adjustable fan controller. I figured if either blows up, I can tell them, hey, the fan and the controller are both yours; what gives? Both the fan and controller are on sale at Amazon.

Here's the fan install. I bolted a couple of 16" long pieces of 1" aluminum L-channel (1/8" web) to the vertical struts on either side of the radiator opening using existing holes, creating a mounting flange. I then bolted a couple of 30-1/2" pieces of the same material across, at the right distance for the fan mounting holes. I used 1/4"-20 x 3" pan-head machine screws bolted through the fan mounting holes, then used a nut on either side of the crossbar pieces so I could hold the fan back toward the radiator.

To get the shroud off, I pulled the upper half up at the seam and slid a hacksaw blade in between the pieces to cut through the staples. The fan is so big, the hood latch and the vertical brace that runs down from the hood latch have to come out to get the fan in. Once everything is fitted, the assembly order is: mount side flanges, mount fan to upper crosspiece, mount bolts on fan for lower crosspiece but do not mount lower crosspiece, mount upper crosspiece and fan between the side flanges, re-install hood latch and vertical brace, slide lower crosspiece behind vertical brace, mount to side flanges, and mount to fan.

I really like how clean the engine compartment came out, and the fan install came out clean as well. Now to clean up the engine and engine compartment from all the thrown spray and see how clean they stay. Also be interesting to see what my mileage does.

In minor testing tonight, the engine came up to temp, and opened the thermostat (it didn't before). The fan turned on and cycled to maintain temperature. It is on for only about ten seconds, then off for almost a minute.

[gmachinz]

Rich, I'm not convinced that setup you have is gonna cut in dry, Texas heat-and you obviously aren't running AC either. I know I'd have to have AC down south! Lol

[rich weyand]

Originally Posted by gmachinz

Rich, I'm not convinced that setup you have is gonna cut in dry, Texas heat-and you obviously aren't running AC either. I know I'd have to have AC down south! Lol

Yeah, you probably want a shrouded puller. I do like the fan and the controller, though. You might think about mounting this fan within the existing shroud.

[notallthere]

I just went electric fans in mine. I used Windstar electric fans and a Painless wiring kit 80203. I did have to make some modifications to my setup but so far after two weeks it is running great.

[chris1htx]

thanks guys for all your insight!

i was leaning towards getting a straight blade fan, but after rich's success with his fan i'm thinking about going with an s-blade fan. i've had the mind set that a straight blade fan will cool a lot better.

[rs72z]

Look for a factory fan setup like the windstar mentioned above. You will be much happier with the performance. But what ever you do get one with built in shroud and it needs to cover all of the radiator core for best performance in the Texas heat and humidity.

[gmachinz]

The one I'm using in my 86K10 is a Crown Vic 2-speed fan. Its 18" in diameter with a built in shroud and it moves a lot of air! Its similar to a Mark VIII fan in terms of CFM pull. Just as important as blade design is the shroud-you basically want to create a miniature wind tunnel. Spal type fans IMO are worthless on their own-it does nothing for you to rely only on blade pitch and speed to move air-far better to incorporate an S-type blade and an integrated shroud. You really need to take a look at a Windstar, TBird, Crown Vic, etc. type of fan. In this pic is a Mark VIII/TBird style of fan...notice the aggressive look of the blades-and the fan is relatively quiet in operation. Vastly different from a Spal type design which requires a lot more blade speed to move the same amount of air. This fan will damn near pull you down the road in neutral! Small children running past have been warned...lol.

[rich weyand]

Straight-blade fans are noisier. More energy into noise means less energy into air movement. Cutting the air cleaner is better, I think.

[gmachinz]

Rich, you don't understand how these blades are designed-they are curved on the edge where they slice through the air. And, the outer edges of the blades have a reinforcement ring for smooth operation and stability-together it creates a tunnel effect. These are quiet at low speed and only moderately noistier at higher speeds. I've used every type of fan imaginable and this design is almost as good as it gets. The 2010-up Mustang GT fans I would rate as the best IMO. Its the same design but with S curved blades so it is a bit quieter. There's nothing quiet about moving a lot of air....lol

[rich weyand]

All I said was that curved blades are quieter than straight blades. Where do we disagree?

[gmachinz]

Oh, lol....I thought you were referring to the blades in the pic being straight...my bad. They have a subtle curve and are actually fairly sharp on the edges....! I've given myself plenty of paper cut type niks in my hands while building fan kits....lol

[chris1htx]

will 2500 CFM be enough to cool an inline 6?

[rich weyand]

Originally Posted by gmachinz

Oh, lol....I thought you were referring to the blades in the pic being straight...my bad. They have a subtle curve and are actually fairly sharp on the edges....! I've given myself plenty of paper cut type niks in my hands while building fan kits....lol

Nah, I was talking about a couple posts back from the pic, when the OP was saying he had his mind set on straight blade for a while.

[rich weyand]

Originally Posted by chris1htx

will 2500 CFM be enough to cool an inline 6?

I would think so, even in Houston.

[rcrahn]

Lots of good info here...worth a read

http://www.thehollisterroadcompany.com/MarkVIII.html

[SkinnyG]

I'm running dual fans from a Ford Windstar, through a starter recall relay from a Cavalier/Sunfire (they are high current relays, and everywhere).

The relay is triggered by a fan switch from some FWD 2.8L V6 I found in the wreckers.

These fans move a LOT of air, and draw almost as much current as my alternator puts out. The fan shroud is almost a perfect fit, with some minor trimming to clear the hoses. I made a simple "L" bracket to tab in at the bottom, and another to attach with the OEM shroud mount bolts.