Keeping your engine at optimum operating temperature is as important to your car’s performance as any other factor, especially when you are talking about force fed applications. WIth summer and the new racing season nearly upon us, we always see an uptick in radiator and radiator fan sales.
And why not? An easy solution would be a nice aftermarket radiator from Koyo, Fluidyne, Mishimoto or more coupled with a set of their slimline fan assemblies complete with a fan shroud get the job done. Which is exactly what our How To Install Universal Slimline Fans article is for.
But what about enthusiasts that do not have a bolt on radiator or radiator shroud available to them? Well today we’ll be installing 2 universal slimline fans to a 1999 Subaru Legacy with a EJ20 swap from a 2001 Subaru WRX.
These slimline fans are both push and pull, and are part number MMFAN-12 from Mishimoto, these fans are in the 700 cfm range and should cool our new engine swapped Legacy nicely. Our How To Install Universal Slimline Fans does not need a specific type of fan to complete.
These 12inch slimline fans come complete with all the hardware and wiring needed for install, unfortunately as this vehicle does not have it’s factory fan wiring in place we’ll be installing a fan controller.
The fastest easiest way to install slimline fans such as these is to purchase a fan mounting kit, usually 4 sticks or plastic pins that can be pushed through the fan and radiator, and secured with plastic clips. You can opt for many different versions of this kind of kit, some with better quality than others.
We personally prefer the B&M 80270 which comes complete with mounting pins, brackets and isolators so that your fan does not touch the fins on the radiator.
Begin by pushing the plastic pins through the radiator shroud and placing the isolators on the front face of the slimline fan. These spacers allow you to mount the fan as close to the radiator as possible, without damage or the possibility of the fan cutting into your radiator or fins.
The EJ20 engine swapped vehicle we are working on also happens to still retain the air conditioning and therefore the condenser unit that is mounted ahead of the radiator. You do not want to push these pins through the radiator AND the air conditioning, so we will be undoing the 10mm bolts that hold the radiator in place to give us some more wiggle room.
Remove the 10mm bolts as shown and gently push upwards to allow the radiator to separate from your radiator support and condenser. Now mock up the first fan and make sure to allow for ample room as we’ll be installing two fans on this radiator.
After you have mocked up the fans you will need to push through the radiator shroud and breach through your radiator to the other side. Once you have the plastic pin pushed through your radiator, secure the clip by pushing on the plastic locking ring and cut away any excess pin that may be poking through.
Now repeat the steps until you have all four push pins through and secured, remember to have your radiator fan isolators put between the face of your fan and the radiator itself.
Here is a look at both of our radiator fans mounted and ready for wiring. As stated previously this vehicle does not have it’s factory wiring from which we can tee the power and ground. We do not want to wire the fans for constant operation as that will hinder the owner and engine from ever warming up, potentially causing poor gas mileage or engine failure.
Cold trim operation is a real concern for turbocharged vehicles, especially stock. Make sure your engine and vehicle are in the optimum range of temperature to prevent any unnecessary risks associated with running your car too cool. You have now completed the mounting portion of our How To Install Universal Slimline Fans guide.
Now with your radiator fans mounted and secured, it’s time to tackle the wiring section of this install. Now we’ve seen shortcuts and hokey solutions before, and they never end up with a happy ending. Do not directly wire your cooling fans to power, as this can cause an engine fire or cooling fan failure.
The correct method of using a relay to trigger your cooling fans is the shown below and the best way to directly get your cooling fans to kick on at engine startup. However as this is not controlled or triggered by temperature, your experience may definitely vary.
Instead we recommend installing a fan controller that uses a thermocouple sensor that can either be pushed into your radiator fans like your plastic clips, or teed into your thermostat neck. The one we most commonly use is a Derale 16759 with the optional push pin thermocouple sensor.
This unit is using a 160 degree sensor and has power and ground wires that you can directly tee into the battery, while using the negative ground trigger to kick your fans on and off. This fan controller unit also comes with a circuit breaker and heavy duty relay mount for optimum performance and longevity.
As these Mishimoto universal fans are both push and pull, now is a good time to combine the pairs of wires by color and test which way you want to wire the fans.
If you guess wrong, simply reverse the polarity of the power and ground wires until you get the fans to pull, or draw through your radiator. Once you have your fan controller wired into the battery and grounded properly, plug in your thermocouple probe and gently push it through your radiator as you did your plastic pins.
Remember that you can always opt for the 3/8th pipe thread version of this sensor and simply drill and tap your thermostat neck to obtain a true real time temperature of your car and engine.
You have now completed our How To Install Universal Slimline Fans guide and the install of your cooling fans! Make sure to test the fans operation as well as the temperature controller you have installed and enjoy!