Hi all,
I finally fixed the coolant leaks & am close to getting the XJS back on the road.
I've go rid of the OEM fan shroud completely, & replaced with a dual electric fan setup, both fans running in parallel (for now - might investigate running independently, or all the time at 1/3rd speed or something in future).

I need to decide what rad temperature to set the radiator fans to come on/go off at - does anyone have any experience, or perhaps know what temperature the OEM auxiliary fan switch in the water elbow was set to?
I'm measuring the coolant temperature in the water return elbow/lower hose, next to the fan switch, which thinking about it probably isn't ideal as it's not 'engine' temperature but rather 'cooled water' temperature.

I have new 82 degree thermostats (ebc3576), & know the left hand bank runs a bit hotter than the right (maybe 5 degrees C or so?) so am a bit nervous about getting the setting wrong.

 

Original switch was 94ºC as far as I remember....but I could be wrong. I've heard other numbers mentioned.

One of the advantages of e-fans is that they come into play only when needed. On my car the switch must be outta whack, or I am wrong about the spec, as the fan operates too often, which I find a little annoying. Mind you, I'm still on the original arrangement of a mechanical fan and auxiliary e-fan.

Anyhow.....

I'm a bit contrarian and less sensitive to coolant temperature than most others. Personally, I'd set the fans to come on when/if the coolant leaving the engine is at 93ºC. That's well before any danger zone and would prevent needless operation. For example, if you're at highway speeds and the temp is holding at (let's say) 82ºC to 90ºC, then all's well and there's no need for the fans to operate.

Let's her what others have to say.

Cheers
DD

 

OEM the temp is 85 degrees C at the thermostatic switch in the water pump inlet. I would wire one to come on always with the aircon compressor and the other to come on with the OEM inlet switch.

 

You also need to wire the fans to come on when the AC compressor is on, it won't cool properly without the radiator fans.

 

After 26 years of running an XJS I have found that I never drive the car without the air con running so both electric fans are always on. So at the end of the day the thermo switch is just a back up so not necessary to detract from factory imo

 

At least until the early 90s the climate control system was configured so that the a/c compressor is engaged in all operating modes, even when heating was called for.

And the aux e-fan was typically wired to operate whenever the compressor was engaged.....at least until 1989-ish.

This meant the e-fan was operating virtually constantly, unless the climate control selector was turned "off"

Circa 1989-90 other schemes began to appear, including different compressor circuits for coupe versus convertible

Cheers
DD

 

I don't have the AC working yet, but my eventual plan was to have them running at a slower speed somehow when the AC compressor was engaged. I was also going to add an AC on/off switch in the interior, spliced into the compressor clutch engagement, so like every other car in existence you can turn the AC off .

The fans i'm using are from the Jaguar X-type - on that car they have a separate fan controller that interfaces via CANBUS etc with the cars ECU to vary the speed. I had to do away with all of that & currently have them setup either full on/full off via relays, switched by a digital temp controller, with the sensor in the water pump inlet elbow.
At full speed they are absolute beasts, quickly pull the radiator coolant outlet temperature down several degrees in seconds, but are very loud & put a really large load on the electrical system so I don't really want to run them constantly as I think there is a real risk of the alternator going pop.

I think i'll set to 82 degrees C for now & see if this is high enough that they stay off when driving at higher speed, & try measuring the outlet temperatures on each bank when stationary to see how high they get with the fans cycling at this temp. I should have done this with the standard setup really so I had something to compare against/aim for but too late now...
I thought there might be additional issues with coolant flow at idle speeds, what with it being an old engine, but like I say, I did observe the water elbow temperature dropping rapidly soon after the fans came on suggesting it's pretty good.

 

Interesting the X Type Fan Pack, as many owners are ask "what can I use"

Mine are wired:

RH as thermo, using the factory 85C elbow switch. With a manual override in the cabin just because, and its never been used.
LH is A/C only, and I have the compressor by-pass installed.

With the A/C on, and our 45C summers, the Thermo fan never cuts in.
Without the A/C, the Thermo rarely comes on, and we are stuck with suburban 50KPH speed limits now, was 60KPH back in the day.

I dont hear a thing in the cabin with that set up, but with both fans running I can just hear them.

I updated to a Bosch 110AMP Alternator (XJ40) at the same time as the Lucas unit was iffy at best.

 

The auto cool guy makes sturdy PWM fan controllers. I used a 100amp unit ( future use proof ) to run my Spals.

Simple to connect, with 10 gauge lugs. This unit ramps the fans speed based on temp and runs on after shutdown if temps call for it.

Fans are off at startup, off at speed, never hit wide open to date, but they were installed this winter so no southern summer data yet.

I can run 2 pushers and 2 pullers and not make the headlights dim. Speaking of that, What’s a standard car alternator output nowadays? I’m looking at LED headlights and they pull 55-65 amps each! Throw a stereo, 4 video screens, digital dash, 18 lighted cup holders and USB charging ports. Max consumption has to be well over 200 amps.

 

JigJag
I run quad headlights with normal bulbs, also two SPALs without a variable speed controller, and my 125 amp alternator - upgraded from the OEM 75, does it all no bother. I do have a solenoid to up the tickover revs when the two SPALs are running though.

 

Here's some pics of the fitment. They are off a UK market Jaguar X-type (2004 IIRC) & are available seriously cheaply 2nd hand as x-type's are very undervalued - I think I paid £15! Replacement individual fan units are also readily available brand new and are cheap.
It clips into the top of the rad, & I had to fabricate simple right angled brackets & cut slots in the fan assembly housing for it to locate at the bottom. Once top rad panel is removed they just pull as a fan assembly straight out the top.
I really need to start a proper thread to document all the stuff i've done as I have taken hundreds of pictures - will get round to it a some point!

pic1:

pic2:

pic3:


My car is a 1989, & has the Bosch 80A (I think) alternator with the multi ribbed belt - are there any threads anyone can link to regarding possible upgraded units for this? I gather this is already a bit of an upgrade over the older system but still not that great.