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Title:Black Magic Fan Install

Author:Kenneth R. Zink

Things you will probably need.

A Flex-A-Lite "Black Magic" electric puller fan kit (# 60) for the 2.5-4.3 liter S-Series, 1982-1997.
An assortment of sockets.
1 or 2 - 3/8" drive ratchet(s).
3/8" drive extension.
Combination wrenches ( I can't remember what sizes, but I do remember that all mine were metric)
Wire stripper and connector crimper.
Wire "butt" connectors

*NOTE* All Black Magic fans include an adjustable thermostat and A/C relay. An optional manual override switch may also be ordered for water crossings and/or mud racing. (#31148)

**SPECIAL NOTE** If you are thinking of replacing or upgrading your radiator, this would be a good time to do it.

Theory of Operation – (lengthy)

First we'll start off with the basics. Most (if not all) S-Series vehicles come from the factory with a clutch fan installed on them. Clutch fans are very interesting in design, in the fact that they use a "fluid" inside the clutch to drive the fan. The prop shaft of the fan is bolted to the water pump pulley and enters the rear of the clutch, which is sealed to prevent the fluid from leaking out. Inside the clutch, there are two sets of blades that face each other. One set is attached to the prop shaft and the other is attached to the "fan" portion of the clutch. This fluid inside the clutch, typically silicon, is a thick substance and at low RPM is viscous enough that it causes the blades on the fan to rotate at the same RPM as the prop shaft blades. As RPM's and wind resistance against the fan blades increase, the fluid in the clutch shears instead of forcing the fan and the water pump to rotate at the same RPM. This keeps the fan from prematurely wearing out the water pump and also puts less strain on the engine as a whole. Since the engine (and the vehicle) are typically moving and air is being pushed through the radiator, instead of needing to be pulled through, the fan is not really necessary at higher RPM's, but is vital for cooling the engine at low RPM's. If the fan didn't slip, it would eat up all kinds of power from wind resistance at higher RPM's and also pots a tremendous strain on the engine, which produces excess heat and wear as it tries to force the blades on the fan through the air.

This is a good setup and has been in use for many years throughout the automotive world. Fortunately, with the invention of the electric fan and scientific progressions, the clutch fan is becoming somewhat out dated. In today's automotive world, many vehicles are coming from the factory with electric fans already installed, but that is not the case with the S-Series. One of the last RWD vehicles being produced with a longitudinally mounted engine in a world where FWD and transverse mounted engines are becoming the new standard for safety and reliability, the S-Series still has a clutch fan for engine cooling. This is not necessarily a bad thing, but when you look at the benefits to be gained by converting to an electric fan, it is not hard to see why I performed this conversion.

First thing first. Clutch fans eventually wear out (so do electric fans) but when clutch fans stop working properly, they die in either one of two ways. The first way is that the fluid inside the clutch breaks down from heat and general use and looses its viscosity. When this happens, the fluid is no longer thick enough to force the fan to rotate at the same RPM as the prop shaft. While this is not a bad thing at high RPM, where MPH and vehicle movement can make up for it, it is detrimental at low RPM's when the vehicle is not moving forward. Sitting in traffic is a good example of this. Because the fan is not pulling air through the radiator like it should and the vehicle is not moving forward fast enough, there is not enough air being forced through the radiator to cool itself down. This can cause rapid heat buildup and if not taken care of quickly, can destroy your engine in a very short amount of time.

The other way a clutch fan wears out is when the fluid in the clutch either leaks out over time or hardens up forcing the fan and the prop shaft to rotate at the same speed all the time. This is know as lock-up and is the opposite of the first problem. Now you no longer have trouble cooling at low RPM, but the engine is now having to work very hard to push that blades through the air as the RPM's increase. If this continues without being fixed, it will eventually cause your water pump to prematurely wear out can severally damage your engine. This second problem, is the reason that I had to replace my clutch fan.

Anyway, electric fans have several benefits over clutch fans. The first being that you remove all the rotating mass and all that wind resistance of the fan from the water pump. This greatly increases the life span of your water pump as well as letting your engine rev easier. Since your engine is not fighting wind resistance from the fan, it also frees up the horsepower and torque required to turn the clutch fan, and redirects it to the rest of the accessories and the transmission. The second thing it does is since the engine is not fighting the fan, it idles a little smoother and your fuel economy picks up a bit. Another benefit of the "Black Magic" fans are that they have built in adjustable thermostats that don't turn on the fan until the radiator reaches a temperature between 180-240 degrees, that you set when you install the fan. This means that as long as your operating temperature doesn't exceed your preset temperature, the fan is not on, unless you hook up the optional manual override switch or you turn on your A/C.

OK, enough of my ramblings, I'm sure your bored to tears after reading that so lets get on with my install shall we?

Installation Instructions

First thing you want to do is open the box and sort out all the parts. The fan kit includes the fan, the mounting hardware, 3 coils of wire (red, black and green), a plastic knob for the adjustable thermostat, installation instructions, a 40A circuit breaker and an assortment of connectors. This kit is pretty complete and has just about everything yo need for the install, but the tools to install with. Take a look at the instructions to get an idea of what is going to go where and how it will need to be wired. OK, now follow the instructions. Ha, I'm not letting you off that easy, you've read this far, you might as well read the rest now. Seriously though, read the instructions and follow them. This article is to guide you though your install with some pictures and inside information from someone that has already done it. All kidding aside, the first thing you will want to do is, with the truck turned off, disconnect the battery. Since you will be working with an electrical device that under the right circumstances be hazardous to your health, disconnecting the battery is highly recommended.

Once you have done that, you will want to start by to remove the screws from the upper portion of the fan shroud. There are several on the side where the upper and lower sections of the fan shroud come together, as well at the 3-5 along the front ot the radiator support so don't forget to remove them too. After you have your screws loose (that wasn't intended to be a pun, but whatever fits), work the upper fan shroud out and proceed to taking off the clutch fan from the water pump. Since my clutch fan was locked up, it was real easy to hold the fan still while I removed the 4 nuts holding the fan and water pump pulley in place. If your clutch fan spins freely, you may need to use another socket and ratchet on another pulley, to keep the accessories from turning while you remove the nuts from the clutch fan. Once you have the clutch fan removed from the the water pump pulley, tighten the nuts back down on the pulley. This will keep you from forgetting to put them back on later and will keep the pulley and belt from taking leave of the engine when you start it. I nearly forgot to do this and was about to start the engine to test the fan, when I thought about what would happen if I cranked the engine with it loose.

If you decided that you wanted to upgrade your radiator or just needed to replace it, the next few steps will be much easier for you. All you will need to do is disconnect your existing coolant hoses and for automatics, the tranny cooler lines. Please use a catch pan for the anti-freeze and tranny fluid and dispose of it in a safe manor. Once the radiator is completely disconnected, pull it out. With your new radiator in a position that you can get to it from all sides, attach one of the retaining brackets to the fan and position it in the middle of the radiator with the bracket hooked around the lip (upper or lower, doesn't matter at this point). Now get your other bracket ready and force the fan flat against the radiator and attach the other bracket to the remaining side and tighten it into place. With the fan attached to the radiator, slide it into place in the radiator supports and you'll be ready to start attaching the electrical connections and re-connect your radiator lines. (for automatics, re-connecting the tranny cooler lines too.) Go ahead and take care of replacing the fluids now, and we'll get to the electrical connections in a minuet of so.

For those of you that didn't feel the need or desire to replace your current radiator, your next step will be to attach one of the retaining brackets to the bottom of the fan. Go ahead and tighten the bolts down, because you will not be able to get to them later. Now is a good time to put the knob on the adjustable thermostat and turn it all the way up. When all that is done, you will need to slip the fan into the fan shroud and gently lift the radiator up about 2 inches to get the bottom retaining bracket into the slot on the bottom of the radiator. With the bottom retaining bracket hooked in place, try and position the fan in the center of the radiator and then gently drop the radiator back into place.

Now comes the fun part, and this step may be easier with the help of an assistant. Believe me, I did this by myself and was wishing I had some help, but was able to get it done without. On the other hand, I also upgraded my radiator to a 3 row not to long ago, so it may be easier with a stock type radiator. Get the top bracket and flatten the fan up against the radiator and attach it. Make sure you have the fan centered before you tighten down the upper bracket. Ok, now that that is done, it's time to start attaching all the electrical connectors to the fan to make it operational.

This particular fan has several different ways to turn it on and off. The first is the automatic, internal thermostat controlled switch. This switch is built in and has the adjustable thermostat that the little plastic knob is attached to. The range of adjustment for the thermostat is from 180 degrees to 240 degrees and allows you to custom taylor what temperature you want the fan to turn on. The theory behind this is to allow you to set the fan to come on once the vehicle coolant temp exceeds the pre set temp (recommended to be set at the normal vehicle operating temperature of 220) and will automatically come on if the temp exceeds 240 degrees, regardless of the temperature setting. You really don't want to exceed 240 degrees or bad things can start to happen. The first of these is detonation or pinging as it is often called. This is where the air/fuel mixture ignites from the heat and pressure before it should, and can cause severe damage to the internal parts of the engine. Another bad thing is warpage of the heads and other parts. When the heads warp, they are for all intended purposes, ruined, and can be very costly to replace.

The second way to turn the fan on and off is the manual override switch. An optional manual override switch may also be ordered for water crossings and/or mud racing. You can attach a switch that will allow you to turn the fan on and off at will. I recommend that you power this switch from an "ignition" plug in the fuse block. That way the ignition will have to be in the on position in order for it to operate and you will not accidentally leave it running and drain your battery. For more information on this switch, please follow this link http://www.flex-a-lite.com/auto/electacc.htm

The third way that I know of to activate the fan, is the A/C relay switch. With this switch powered, the fan will come on and stay on as long as your air conditioner compressor is active. One the A/C compressor is turned off, as long as on of the other two switches doesn't have the fan running, it will shut off. The reason behind this switch is that the A/C condenser needs to have air flowing across it in order for it to cool the compressed R12 or R134a refrigerant that cools the air blowing through the vents.

With all that in mind, decide whether you want to install either of the last two. I recommend installing the A/C switch if you have an A/C, and if you do alot of off-roading or water crossing, the manual override switch.

Ok, now that you have decided what you want to install, lets get to it. We'll start by finding a good place to attach the 40A circuit breaker. I pulled the battery out of my truck to do this next portion. I attached mine to the front portion of the battery tray, between the headlight bezel and the battery. I then ran some of the red wire (included with the kit) from the female spade connector (plugged into the high amp positive plug) on the fan, out around the opening of the fan shroud and then to a ring terminal (connected to the attached to the closest post) on the circuit breaker. Next I made another run of red wire and connected to a ring terminal (attached to the other post of the circuit breaker) and up to where the positive battery terminal would be. Now I made a run of black wire (also included in the kit) from the negative or ground plug out around the fan shroud and over to where the negative post of the battery would be. I then put my battery back in, to make sure that nothing was going to get into the belts and pulleys while the engine was running. After that, I ran more red wire from the the Low amp positive plug (connected with a female spade connector) out around the fan shroud, over to the wire wrap from the positive battery post, and followed it (inside) around the engine compartment to the fuse block. From there I feed it through to the passenger compartment through the firewall, and attached it into an ignition terminal on in the fuse block with a male spade connector. I did this to keep the fan from running when the truck is off and draining the battery.

I opted to attach the A/C switch on my fan, and because it was stating to get late, the fact that I will be pulling this engine soon for a 3.4L upgrade, and the fact I was being eaten alive by mosquitos, quickly ran the wire for the A/C power. As you can see from the pictures, I just ran the green wire from the A/C plug on the fan, behind the shroud and over to the A/C compressor, and spliced it into the A/C power wire using the 3 way connector and then wrapped it with electrical tape. I suggest that you run it around the engine compartment in a wire wrap and come at the A/C compressor power wire from the firewall side of the engine. This makes for a much cleaner install and less chance of getting it caught in the belt.

Since I don't Off-Road my truck, I decided that a manual override switch was not necessary and re-connected the battery. Making sure everything was ready for the first start-up with the electric fan, got in to start the truck. NOTICE that I haven't put the upper fan shroud on yet. There is a reason for this. You need to have it off the set the adjustable thermostat, and you can't get to it with the shroud in place. It was at this point that I realized that I hadn't tightened the nuts down on the water pump pulley, and immediately got out and tightened it into place. Once again, I looked everything over and got back into my truck and clicked the key over into run, but not start. The fan didn't start up right away, and since I didn't have my A/C on and the fact that the radiator was no where near hot enough to trigger the thermostat on the fan, considered a good thing. Since my A/C was off, I reached over and flipped the switch to turn it on. The fan roared to life and began pulling air through the A/C condenser and radiator. Confident that the fan worked, and that it didn't dim the interior light considerably, I turned the A/C back off (and the fan) and started the engine. At this point, I got out of the truck, and popped the radiator cap off and waited for the engine to to warm up enough to open my thermostat and begin to circulate the coolant through the system. It was a few minuets before the fluid in the radiator started to flow, and at that point, I reached down on the side of the fan and slowly turned the knob until the fan once again roared to life, and turned it just a little more, so that the fan would turn on at about the same time the thermostat in the engine opened. With the thermostat now adjusted to where I wanted it, I once again got into my truck and switched the key off. The engine died immediately and so did the fan. With extreme pleasure, I found it extremely necessary to exclaim my happiness with a loud "Kick Ass!" that my neighbors probably wanted to lynch me for being that it was nearly midnight (Big Grin). Oh well, they'll live, and got out and attached the upper portion of my radiator shroud and inserted the snorkel onto the air cleaner and dropped the hood for a test drive.

I don't recommend doing this next part at all, but I just couldn't help myself.

Being that I had just driven my truck for a week back and forth from work with a locked up clutch fan, I was a little more then eager to try out how this fan would improve my performance. I started off quietly and with the A/C off and the windows down, I worked worked my way out of my subdivision to a long and curvy road. It was a cool night, about 72 degrees and for a change, the humidity in Houston was fairly low (for Houston) and I was enjoying my slow drive. Well, just as I was turning out of my subdivision, I floored it. My truck is powered by a mighty 2.8L (I'm serious on this matter), and immediately sent my outside tire into spin city and didn't regain traction until I was completely through the turn and had straightened out the front tires. Of course, this was almost to much for me to handle, so I proceeded to the nearest stop light at a very rapid pace and to my luck, it was turning yellow as I approached it. I could barley hear the fan running, but could immediately tell that the throttle response was better and the engine revving was easier. Watching the cross traffic (none) and their green light turn yellow. I got on the brakes with my left foot, dropped my floor shifter into first, and brought the engine up to about 2300 RPM with the right foot and watched my light. That seamed like the longest, reddest red light I've ever waited on. GREEN, I floored it and pulled my left foot off the brakes at the same time. She spun the tire (I really need to install that posi unit and 3.42's, and replace this open 3.08's), caught and took off like never before. 33 MPH and 5600 RPM, I slapped the shifted up into second. 67 MPH and 5600 RPM, I slapped the shifter up into third. Still with my foot in the gas, I was now doing 85+ (I don't know how fast I was going now, because my speedo stops at 85) I decided that it was time to get back out of it and I could see headlights down the road and bring it back down the the posted 35. WOW, I knew my truck could move before, but this was unreal. I resolved that I was going to have to go back to the dragstrip.

I do recommend doing this part, but again I just couldn't help myself.

The week before I was on my way to HRP and was about 3 miles form the gate when my clutch fan first started acting up on me, but I ran her anyway. Needless to say, the times sucked, but even with the fan locking up on me, she still ran her best (and worst) times ever. My truck is an '87 GMC S-15 Ext. cab with a 2.8L engine, 700-R4 tranny, 3.08 open gears, and on a good day weighs as little as 3720 Lbs. My best 1/4 mile ET was 18.587@72.51 (about 113.884 RWHP) and my highest MPH was 18.587@72.51 (about 110.090 RWHP). Well I ran her again that next Wednesday. Best 1/4 mile ET was 18.095@76.27 (about 124.095 RWHP) That's an improvement of .492 Seconds and 10.211 RWHP. But wait, my best MPH was 18.185@76.34 (about 129.167 RWHP). That's an improvement of 3.83 MPH and 19.077 REAR WHEEL HORSEPOWER!!!! I was more then just a little happy and proceeded home after 14 passes.

Conclusion

In my opinion, If you are looking for a fairly cheap way to increase the longevity of your engine and free up some ponies in the process, order yourself one of these fans and install it. You will be amazed at the increase in power and ease of install for the price.