Installing an Electric Fan

The mechanical fan robs you of 5 to 10 hp at highway speeds. The engine is powering the fan for no reason, the air moving at 20 mph and up is more than adequate to cool the rad. An electric fan is only on when you need it. I've purchased an electric fan and found two radiator fan temperature switches to use. The radiator fan temperature switch turns on the fan when the rad gets hot and off when the coolant cools down.

  • 1980 VW Rabbit 1.5L 203 +/-5 degF (Wells SW533 or Standard TS-151) M22 x 1.5 threads
  • 1991 Subaru Loyale 1.8L 203 +/-5 degF (Wells SW554 or Standard TS-183) M16 x 1.5 threads
  • 1987 Buick Regal Grand National 3.8L Turbo 210 degF on, 205 degF off (Wells SW555, Standard TS-136) 3/8 x 14 threads

My 1992 2.3L has no temperature sensor mounting hole in the block or thermostat housing so I had to make an inline one - basically a metal tube with a bung soldered to it so that the coolant temperature switch can screw into it.

Here's how I replaced the mechanical clutch fan with an electric fan. First I purchased a used 14" electric fan online. The model number is MT130P part #14-401353 130W 12V about 1700 CFM.

First you got to remove the original clutch fan

There are four 10 mm bolts that held the clutch fan onto the water pump pulley shown here. You can remove the fan without taking the fan belt off. A bonus is now there's lots of room to work on the front of the engine! Wahoo!

I found that after removing the radiator fan shield that you can move the shield mounting bolts outwards and they will line up nicely with two bolt holes in the bottom of the rad. I'll use 20" x 3/4" x 1/8" strapping vertically between the top and bottom to hold the electric fan in place. The strap mounting holes are 19" vertically apart.

Now this is something that doesn't happen too often. I drilled some holes for mounting screws in the fan shell and the 13" horizontal width lined up perfectly with the radiator mounting holes pictured previously. The fan mounting holes are 7 1/4" vertically apart. The up arrows are to indicate in which direction the two straps mounting holes line up. I centered the fan in the middle of the rad. You can see the strapping is already screwed in place with some flat head bolts. I ground the heads flat with my benchtop grinder than spot welded them to the straps. There is very little clearance between the straps and the radiator fins.

Here's the plans for the two fan supports.

Here's the fan mounted on the radiator. Notice that without the fan shroud/shield, the coolant reservoir hose has to be rerouterd. I had to zip lock the hose from the radiator cap to the coolant reservoir to the top of the radiator.

Here's the schematic for the fan wiring. The automotive relays have standard numbering for the pinouts. The color code unfortunately is not standard. You can read more about automotive relays here.

Here you can see the wiring wrapped in a split loom. The fan temperature switch is on the rad hose. I tapped the +12V off the battery and put a 15A fuse inline for protection. You can see that the fan is tight against the radiator fins.

In this picture you can see where the relay is tied down. You can't control the fan directly from the fan temperature switch. There is too much current draw from the fan, it would burn out the temperature switch. You need the fan temperature switch to control a relay which provides +12V to the fan. The relay I used is a standard 30A automotive relay.

The biggest thing that I noticed so far is how much quieter the engine is. Without a mechanical fan, it's pleasantly quiet. No roaring on startup when it fast idles at 1500 rpm and no roar when I'm driving along at 2500 rpm. This was a nice bonus that I didn't expect. Also the electric fan is amazingly quiet when it runs - whisper quiet! Unfortunately, Fall weather has hit and it'll be a long while before the weather warms up enough to need the fan..

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Copyright February 2011 Eugene Blanchard