Replace the engine-driven fan + clutch with a Ford Taurus or Lincoln Mark VIII electric fan. Frees up 5-10 HP, better idle cooling, mandatory for V8 swap.
The factory mechanical fan robs 5-10 hp depending on engine speed and clutch lockup state. Removing it and switching to a junkyard Ford Taurus or Mark VIII electric fan is the canonical XJ cooling upgrade.
Fan choice:
Wiring: the Mark VIII fan needs a real controller (Derale 16795 or similar adjustable thermostat plus a relay rated for 80A continuous). The Taurus is more straightforward — three wires (hi/lo/ground), two 40A relays, a 195F adjustable thermostat in the upper rad hose, and a keyed power source. The fan should be triggered by both the thermostat and the A/C clutch (if you want A/C to bring the fan on).
Common mistakes: undersized relay (puff of smoke, no fan), no fuse on the battery feed (fire), running the fan unswitched (battery drain), forgetting A/C trigger (A/C overheats at idle). The gojeep.willyshotrod.com writeup is the most-cited reference.
Additional benefit: less belt drag, quieter, no fan-pulley wobble loading the water pump bearing.
| Part | Vendor | Est. price |
|---|---|---|
| Ford Taurus fan (junkyard) | junkyard | ~$50 |
| Lincoln Mark VIII fan (junkyard) | junkyard | ~$100 |
| Derale 16759 adjustable thermostat | Derale | ~$65 |
| Volvo 80A relay (for Mark VIII) | Volvo OEM | ~$35 |
| 40A automotive relays (qty 2) | Bosch | ~$20 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.