I know it is not the best looking solution, but sure as hell it is functional and a lot more cost effective then $600 eBay option.

Long story short, 5 series (e39) 2 speed fan housing gets trimmed to fit in XJS fan opening. Than plastic fan housing gets screwed around, with 4-6 screws every 90, or 60 degrees, lastly gaps all around get filled with high density window insulation foam.
To make out side presentable, I covered foam with liquid electric tape + some flat black spray paint.

Electric system is based on 3 relays and rather simple.
relay one - accessory fan power (the small one)
relay two - main fan half speed
relay three - main fan full speed
System is fed off left 12v terminal on firewall and actuated off any ignition switcheable terminal in left front corner. I think I used horn relay's solid green wire.

When ignition is on, main fan spins half speed all the time, however when thermo switch (located near water pump) is engaged, small fan kicks on and main fan switches to full speed.
This system is simple and works extremely well, even on the hottest day in traffic.

 

My man, Necessity is the Mother of invention. -If you want function over fashion (or purity of breed), you just do what you gotta do.

 

Very nice mod I would like to make on my 89 XJS... I still have the yellow fan and read that these become brittle and fail, and can take your rad out?

I'm not so much into electrics and switches and relays that would be difficult for me...

 

I can draw a diagram sometime. Totally agree on the blades, one of mine flew off and severed radiator, plus another one brazed my father's in law neck.

 

I ignored the small subtle cracks that were in my yellow plastic fans. That is until it exploded and took out my radiator! I just used it as an excuse to upgrade to an aluminum radiator. I have heard of them exploding and puncturing the bonnet as well.

 

Next to changing the oil radiator, I will look for a salvage e39 cooling fan, it would be nice to see a drawing that indicates which wire connects to which other wire! Thank you very much.

Greetz,

Frederik

 

When you chuck the mechanical fan, the main decision is how to trigger the replacement electric one, that is, what type of thermostat to use and where to place it. If you cannot find a suitable fan at a breakers, brand new electric fans are not that expensive.

The main power for the fan is best taken from the bulkhead post, while the low current power for the thermostat can be taken from any ignition-switched source (mine comes from the + feed to the coil).

The thermostat options you have are many, but if you are buying a new radiator, it is an ideal time to select a thermostat system and have the radiator maker weld a boss into the new radiator to screw a thermostat sensor into. Towards the bottom of the radiator just by the outlet is best IMO, as at the top the temperature is very variable and the system can keep switching on and off every few seconds and blow the switching on and off relay. Or you can use the OE thermostatic switch on the water pump inlet, and easily rewire the existing small electric fan to come on with the aircon permanently. When the time comes, loads of people will help with the wiring.

Greg

 

I believe I used E36, or E39 A/C pusher fan, the one that goes infront of the radiator assembly. These are 2 speed, which is important because in normal driving conditions full speed never kicks in, while half speed is enough to keep A/C working well. Otherwise, one would have to complicate system with large fan to kick on full speed, when a/c is engaged.