I do have MOSS Motors Lucas British 50 amp fuses. Do you think that a 14 gauge wire would be acceptable? If I don’t employ these fans on this car, I intend to take a well-used early Series III E-Type and build for performance, not stock concours prep. That would be a perfect use for these fans. Returning to stock is fine, but I will have to rebuild those stock fans; one of them is making a horrible screeching sound. Moving onto the AC system.
Many thanks again for your comments, very much appreciated.
Well, we’ve figured this out. The Moss fuse has a 25A continuous rating. You’re probably close to the safety limit of a 14 ga wire @25A. So if you want to tug on that thread, you will need to either run a new 12ga wire or a second 14ga wire.
I have two GENUINE VW dual speed fans in my S3. I’ve connected them to the fans’ high speed circuit only.
I’m really not sure of their actual wattage but when they run, you know it… Unfortunately I don’t have an instrument capable of measuring that much current. This is how I have connected them using 30A relays with a 30A fuse in each line and using 4mm² fine multi-strand wire all the way from B+ to the fans.
I wired them directly from the alternator B+ output (as shown on the diagram) so that:
the current for the fans place no load on the original wiring of the car;
the highest possible voltage is available to the fans (using the cars wiring introduces voltage drops (and heat) at every connection)
The fuses are located physically close to the alternator. I have no problem with blowing fuses.
I intend buying a measuring instrument and will then report on actual current drawn. I should add that the alternator in my car is a 130A Bosch from a LR Discovery 2 4.0 V8. (130A alternator)
I installed Ron Davis fans about 15 years ago. Since my otter switch was unreliable is shorted across it so that they are always running when ignition is on. I did have a problem in the beginning when running them with the OE relays, after a short time they would burn out. After replacing them with the solid state relay that came with the kit I never had another problem. Also still have the single 35A in-line fuse above the battery. Works fine.
OMG, this is such great news. Great idea to run a 12 gauge wire when running both fans off the same line, and a great chance to improve my solder technique on the connectors. Should I be concerned about the alternator? When all accessories are on, including AC and headlights, radio, etc., do you think that 70 amp alternator is up to the task? What might be out there to increase capacity?
Once again thanks so much for your help, I wouldn’t be nearly this far along without it.
Very good. Did the solid state relays come with the Ron Davis fans? You mentioned a “kit”, was that the fan kit? Thanks for your comments, glad your car is working and running well.
Great set-up, thanks for sharing this. What are the part numbers for the fans, and fluke amp clamp you used. I’m in the market for an amp clamp . Many thanks for posting this info and fantastic photos.
This is most helpful. I have ordered an amp clamp to measure currents in my system. What alternator are you using that generates 130 amps? The stock unit is rated at 70 amps. Thanks so much for your comments and your chart.
Here’s the write up on the VW fans. PN’s are examples, VW seems to have produced the same thing under many different PN’s. The source is 80’s-90’s Jetta/Fox.
Its a Bosch alternator from a 00 - 04 Land Rover Discovery 2 4L V8. Again, I did not fit this for its amps, I fitted it due to its form factor which made it very easy to adapt/fit it to the V12 and I had it lying in my cupboard. Many believed it would set my car on fire, but few understand why it won’t and hasn’t, since Oct 2018
Yes they did. By kit I mean the fans, relays and a heat sensor to be used instead of the otter switch. I didn’t use the sensor (supposed to be glued on top of the radiator) and kept the otter, connecting its two leads so that the fans always run.
Edit to the original post: I had cooling issues so installed a Ron Davis radiator first. Then I upgraded the fans. They are not from Davis but sourced from XK’s Unlimited - that was 15 years ago and I think the brand was Scott. Those helped but didn’t cure the problem.
Ultimately it turned out to be much simpler. I had had the V12 pulled to fix leaks at rear main and rear gearbox a few years prior. Bottom gaskets replaced too. The mechanic re-attached the large water pump to oil cooler hose with too much length so that on re-install the angle in the hose was impinging on the lower picture frame, cutting its volume by 30-40% at that point. Very little clearance there and difficult to see. Only when I replaced that hose did I see the permanent “dent” in the old one.
WOW! Obviously you have spent many hours under the bonnet detailing your engine room. That alternator fits exceedingly well into the tight space between the engine and the radiator. Immaculate installation, including Jubilee clamps on hoses. Thank you for sharing these great photos, this level of detail and craftsmanship makes me want to disassemble everything and start over! You must have a very interesting cupboard. I was going to search for an 80 amp unit to replace the stock 70 amp alt. I too imagined the 130 amp unit would be overkill.
Thanks again for commenting and sending over the inspiring photos.
The V-12 Jaguar cooling arrangement certainly has many more parts than a simple radiator, engine fan, and hoses. How frustrating (i.e. expensive!) for you to perform all of that work to still have the same overheating problem. I was so pumped when I got the car back from the restorer with a new paint job, new interior, and a new aluminum radiator with ungraded fans. I thought my problems were over, now just pure enjoyment. After thoroughly embarrassing myself on the Concours field as this beautiful car steamed and spewed all of the way across the field, I decided never again. The car is such a pleasure to drive without the cooling gremlins. Congrats on getting to the bottom of your issues and enjoying your car.
Thanks for your reply and your detailed explanation, very much appreciated.
The Bosch alternator is much smaller than the Butec and significantly lighter, FWIW.
For the record, now that I found the fan switch temp ratings to be the main cause of my car’s cooling issues, I firmly believe that the VW fans are no longer needed (original fans will do fine) and that the Butec would be quite strong enough to deal with max current consumption on the car.
I tour far and away with my E and knowing that it has a modern and common alternator gives much peace of mind. Same argument applies to the fans.
Thank you for confirming my thoughts as well. The more I have studied and fiddled with this, coupled with all of the helpful comments I have received, I came to the same conclusion. I’ll carry a spare Butec in the boot, and all should be well. Now to get to work at making my car functioning and looking as great as yours. The Austin Healey Club tours coast to coast, and I would love to join them in the Jag, reliable and worry free.
