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Electric Fan Conversion

Electric Fan (e-fan) Conversion

Alex Cannara

The stock mechanical fan and clutch on the XJ6 will do a good job of keeping engine temperatures under control. Removing the stock items and installing an electric fan system will not solve overheating problems caused by things like a plugged radiator.

That said, the mechanical fan components do fail. The clutch can either cause the fan to freewheel at all times, or seize up, causing the fan to spin too fast. The former condition can obviously cause overheating problems in traffic. The latter can have somewhat catastophic consequences, especially on cars fitted with a plastic fan. The plastic fan is, over time, susceptible to cracking. Spin a cracked fan too quickly, and the resulting forces can cause the fan to fly apart, potentially damaging radiators, distributor caps, fan shrouds, hoses, and the bonnet. Driving with a cracked fan can be a very expensive proposition, not to mention the possibility of being stranded on the side of the road.

When faced with replacing your fan, many choose to stick with the factory items. Unfortunately, the OEM fan is relatively expensive (over USD 200). Some have used various aftermarket mechanical fans. Others, such as Alex Cannara, are strong supporters of converting to an electric fan system. The benefits are that it's a relatively inexpensive system, it's reasonably quiet, doesn't rob signifcant amounts of engine power, and can be configured to run even with the ignition off to minimize underbonnet heat build-up after parking.

There are of course, different vendors of electric fans and controllers, and many different ways to go about installing them. Here is Alex Cannara's guide to installing an e-fan (on the Series II, others similar). Click on any picture for a larger version.

-Chuck Renner

Cannara's Hayden electric fan and controller modification for the XJ6
Revised Oct 2002

Here are some steps to go with the pictures of our SII's mod (SIII is very similar)...

Remove engine fan, clutch and upper and lower shrouds (SII). Keep one upper-shroud angle bracket and all 1/4-28 bolts -- clean and repaint bolts, or get new ones, preferably stainless. Buy some 1/4-28 nylon-insert locknuts and flat washers, all preferably stainless.

Choose the fan diameter and location(s) -- a 12" (#3680) will fit nicely in front of the A/C compressor and can use the existing hole in the radiator frame for its upper mount (using the saved angle bracket). Larger fans (e.g., 3690, 14") may require more drilling of the upper radiator frame, but may be needed in hotter climates. Two of the smaller fans (12"), mounted diagonally, may be the best way to go overall -- decide this before proceeding. Note that there's no advantage to have the fans vertically overlap, thus both cooling the same horizontal set of radiator tubes. Also, on an SIII, you might want to have a fan cover the upper air passage above the radiator top as well. The 12" fan draws only 7 Amps, the 14" about 9 and the 16" one about 11 -- test before proceeding to be sure each works. As a benchmark, the 14" fan delivers a very adequate 1000 cubic feet per minute through a typical radiator. No shrouds are needed, so clearance at the front of the engine becomes wonderful.

Get the #3647 controller and mount it via 2, 10-32 threaded holes in the center (SII, one side for SIII) of the top frame over the radiator -- see pictures. Use brass or stainless screws for mounting -- watch drilling depth and screw length so as not to hit radiator itself (1/2" screws will work fine).

Clean 4, 1/4-28 bolts, mix some epoxy and press the bolts into selected slotted mount receptacles on the fan housing, with epoxy under and around them -- you may have to grind a little off opposite sides of the bolt heads to get them to fit the mounting slots. Put a 1/4" flat washer on the outside surface too -- see pictures. For the 12" fan in front of the A/C, the mount slots used are: top, lower-left and both right ones, as seen from engine side. Note that the fan blade may need to be unbolted and reversed to push air toward the engine (I also painted it yellow -- a fetish).

Make 2 aluminum brackets, per pictures. The vertical one is 3/4" x 1/8" angle stock, cut at top end to allow bending for proper fan-radiator clearance (about 1/4"). The horizontal one is W shaped 1" x 1/8" aluminum, bent so it can be screwed to the front of the frame below where the hood latch mounts. The rear will be bolted to the lower left fan mount. Drill appropriate holes in the brackets and frame -- using the 12" fan also allows using the slotted hole in the lower radiator frame for the vertical bracket's lower mount. If you don't bend the lower end of the vertical bracket to meet that point, make a third bracket out of angle or flat stock for the bottom end -- see picture. When the epoxy dries, the brackets and fan can be test aligned and any adjustments to holes in them or the radiator frame made. Note that the old upper angle bracket needs to be bent so its lower portion goes a short way forward and under the radiator frame, to match the alignment and spacing of the fan from the radiator's rear surface. The W bracket's frame mount is by self-tapping screws into the front of the side frame, so the bonnet may need to be removed. Mount any second fan in a similar way, but on the lower right of the radiator, as seen from the engine.

Optionally, degrease and paint all metal parts black. Mount the fan and bring its ground wire to a good point on the frame, such as a mounting bolt for the bonnet latch. Bring the blue wire up through the grommet by the headlamp relay (SII) and over toward the controller. Solder a ground lug to the controller's black wire and put it under the nut holding the top end of the vertical bracket to the radiator frame -- clean to bare metal on the frame and use a locknut, lockwasher and oil. Both ground wires should have soldered lugs and be mounted on lockwashers on bare, oiled surfaces. Do the same for any second fan.

Now make a fusebox for 3 Littelfuse or Buss 3AG holders (see pictures). This is also mounted via two screws into 10-32 threaded holes in the radiator top frame. Drill holes for a 1/2" grommet at the controller end and a 3/8" one at the other. The fuseholders should face forward. Mount the box with some sealing grease underneath, using brass or stainless screws.

Feed the orange, blue, red, yellow and green wires from the controller into the box via the big grommet and solder the orange wire to the fuse (end contact) nearest the controller, the blue one to the next holder, and the red and yellow to the last (but to its side contact). Bring the blue wire(s) from the fan(s) into the box via the 3/8" grommet and solder to the side terminal of the fuse with the blue wire on its end contact. Bring the green wire through the box and out (making no contact) and down through the grommet the blue wire came up through -- the green wire is optionally available for connecting to the green A/C clutch wire. Wrap the green wire in a neat bundle and tie-wrap it to the A/C hose or something. Use a red or brown #12 or #14 stranded wire and put a solder lug on one end that will fit on the alternator's power bolt (or to the stud on the firewall). Add some shrink tubing to the bare neck of the lug. Pull this wire up through the same path the blue fan wire took and solder it to the end contact on the fuse holder with the red and yellow wires. Put a 20Amp fuse in that holder and 10Amp ones in the other two -- you'll use the latter to feed one or two fans. Put spiral wrap around the wiring to and from the fuse box (see pictures).

Drill a hole for a 3/8" grommet in the vertical part of the upper radiator frame (see picture), insert grommet and pass the sensor probe though it and over toward the inlet portion of the radiator. Coat the probe with silicone grease and carefully jam it between some radiator fins an inch or so down from the top of the radiator and in from the inlet hose -- it should be under the air-intake passage (SII). Put spiral wrap around the sensor wire and back through the grommet. Use a mounting clamp to hold the wire (can use the same screw and captive nylon insert that was used for that side of the SII's upper shroud). Tie wraps can be used as well.

Connect the red or brown wire with the solder lug to the alternator's power bolt (under A/C compressor), or all the way back to the firewall stud, using tie wraps or clamps as necessary for neatness and safety. Clean the power bolt as necessary, maybe change to brass nuts & washers, and oil before tightening. Be sure the controller's relay and fuses are in place. Start the engine and drive or idle the car until warm -- the fan may come on. If not, turn the little white screw on the controller clockwise (lower temps) until the fan comes on. The desired setting is such that it comes on before the aux fans (only one aux on SIII) do, but not before the engine reaches proper temp. A second fan can be added, if necessary, by grounding its black wire and bringing its power lead up to the side lug of the fuse with the orange wire. Note that the fan(s) may often come on after parking, because the latent heat in the engine can raise the radiator's temp via thermal siphoning, even when no longer moving. This is good. You're cool.

Another feature can be added -- a diode from the Aux-fan relay to the fan power for one or both new fans. This will provide a fail-safe system, should the Hayden controller fail. Ideally, two diodes, one from the controller to the fuse for that fan, plus one to the same spot, but from the Aux relay. The two cathodes (banded ends) should connect to the fan fuse. It's likely best to feed the fan in front of the A/C and exhaust this way. Now you're cool and confident!


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