So a few questions. Both of these fans came out of 2003 Discoverys with a 4.6. Why does 1 have a ring and other doesn't? Why is one fan a 2 piece where as the other is epoxied together? Is the clutch from the 4.0 the same as the 4.6? Is the fan itself different? Are the fans from the P38 the same as the D2? Are they interchangeable? Is there a cooling output difference from one to the other?

Main reason I'm asking is 1 of my trucks is running hot. About 208-212 idling. The electric fan is working too hard. Down the highway seems cooler but still hot. I have a new radiator, 180 degree thermostat, all new hoses and not a single leak, new coolant bottle cap. Why the heck is it running so hot.

 

03-04 D2's went with the one piece clutch/fan blade unit. It has no benefits to it vs the 99-02 2 piece setup. The 03-04 setup cost 299.00 while the 2 piece unit cost 25.00-60.00 for the fan blade (Dorman 620-112 or OEM LR Unit), and the fan clutches range anywhere from 25.00-55.00 depending on which one you go with. Which leads me to the other advantage of the 99-02 setup you can choose, standard duty, Heavy Duty, or Severe Duty fan clutches. You can NOT do that with the 03-04 one piece unit.

I'm in TX and I run the Heavy Duty or Severe Duty fan clutch paired with the Dorman 620-112 fan blade. There is nothing wrong with the OEM fan blade, I just found the Dorman 620-112 is a perfect replacement at half the price (using the 620-112 P/N you can find other brands as well).

The main thing on a D2 is to make absolutely certain you have a true 180F thermostat (I've personally seen plenty of them from no name companies). Then make sure your fan shroud upper/lower is in good shape and seated properly (especially the bottom section). Then make sure the side plastic bits are in place as well. You want all the air you can to be channelled thru the fan blade.

With a 180F, Severe Duty Clutch, Dorman fan blade in TX I see temps from 184-215F. It all depends on the season, the ambient temp, your load, your speed, your terrain, and it's even as sensitive as pulling out from behind a vehicle drafting and putting more load on the engine. Whenever you reach the area where the engine speed/air flow level out and can no longer keep up with the heat being produced the temps will rise. D2's with the OEM setup (no experience with the inline mod as I haven't seen that drastic of a difference) will have the temp rise by as much as 10F then it will fall again. The rise/fall will continue on the trip until it either gets cooler outside or you slow down enough for the engine to keep up with the heat produced.

I've been wanting to install some hood vents to see if it makes a huge difference. The JK hood vent would fit perfectly on a D1/D2 hood. I just don't want my LR to look like a Jeep lol.

 

I’m in south Florida, was having the same issue after doing some preventive maintenance. Bought a so called 180 T from Lucky8 and temps actually went up not down.(210-227) As stated, make sure your thermostat is opening fully and really is a 180t. I pulled mine out, did the old fashioned stove top test. And found that my 180T would start opening at 210 and would never open fully. Threw it in the garbage. Picked up a genuine Land Rover grey 180t and my landy know runs at a consistent 184-188 on the highway. 188-195 slow driving with traffic. And 188-206 max if off roading 206 degrees was when I was almost stuck and trying to get out. Once I got out and started moving again my temps drastically went back down to 188. I even went to the extent of purchasing the 99-02 fan blade and was going to purchase the Hayden 2991 clutch. But with the temps I’m running it’s not necessary. I will install it when needed though. My clutch is fine. The 99-02 fan blade mod is definitely an upgrade. There is nothing wrong with your stock 03-04 fan set up if it’s working as it should. The draw back is the cost.. also when and if you drain your coolant use green 50/50 coolant and a bottle of water weter. It helps too.

 

Yep the so called 180F that was actually an OEM temp of 190/195 = came from Lucky8. When Lucky8 sold the Britpart 180F that was actually stamped 78C and it came in a brown cardboard box with Britpart on = AWESOME thermostat. However the black 180F they sell now = generic no name & it's not 180F. Hopefully Lucky8 has fixed this, but if I ever order another thermostat from Lucky8 it will be the OEM Grey.

I've just been buying the 180F Motorad unit locally from Auto Zone vs getting it online. Zero issues on about 5 friends/customers LR's.