P38 Range Rover Cooling System Upgrade

Summary The original radiator on my P38 was leaking, so I decided to replace it with an uprated one from Aussie Desert Cooler. I also decided to replace the engine driven fan with a Thermostatic Electric Fan, also supplied by Aussie Desert Cooler. I decided to use a Dakota Digital Controller because I was originally hoping to get twin fans but two 14" fans would not fit and the single 16" pushed more air than a pair of 12" Since I finished up with a single fan I was wondering if I could use the other fan control channel when I came across a thread on rangerovers.net which described how to use the factory air con fans as an emergency cooling, so I decided to hook these fans up to the second channel on the PAC-2750. The PAC-2750 also provides a run on function for up to 5 minutes and works with a variety of senders including VDO and can even be custom calibrated. The run on function has a low voltage battery protection as well, which is comforting in a P38 ;-) I laso made sure the new Radiator has a good earth connection, which surprisingly it did not until I added an earth cable Once everything was installed I used an Analogue multimeter to check for any stray voltages which causes electrolysis. There is some Information here   and more Information here The advantages of this setup are better cooling and about 8% increase in available power resulting in better fuel consumption.
Radiator The upgraded radiator is basically a direct replacement, though I did have to shorten each of the top hoses by about 10mm
As you can see it is a fair bit deeper than the original. Click on the image for a larger version	This is the assembly with the 2700 CFM 16" electric fan and shroud fitted. Click on the image for a larger version	Installed in the beast. Click on the image for a larger version
Fan and Controller After doing my research I decided to use a Dakota Digital PAC-2750 Dual Fan Controller I also purchased a BIM-01-1 OBDII Interface I was hoping this would talk to the P38 so I could pick up the temperature and road speed from the Interface Unfortunately it would not talk to the ISO 9141-2 on the P38 and after attempting to pick up the signal from the factory sensor and failing, I decided to get a dedicated Dakota Digital sender The next problem was where to mount the sender. I hit on the idea of a custom T piece with a spot to mount the sensor. Aussie desert coolers made this up based on a drawing I sent them. This replaces the original T piece which is not a separate item but is sold as part of the top hose I specified 30mm OD tubing for the large pipe where I should have specified 35mm tubing, I intend to have another made to fit a VDO sensor so I can install a decent temperature gauge The adapter for the sensor The sensor in position in the top hose
Connections I wired up a relay and attached it to the rear of my battery box and hooked it up to the controller and the fan I have currently set up the controller to bring the fan on at 96c and off at 93c, I have also configured a 2 min run on delay on switch off. It seems to maintain the temperature very well, it comes on for around a minute and goes off for a couple of minutes when the car is idling, the temperature sender is very sensitive My next step is to hook up the factory condensor fans to come on at around 101c and to add a manual override switch under the bonnet. All feedback, comments and corrections are very welcome, send to the email address in the home page.