Although I've fitted 'efans' I haven't yet wired them up but I was wondering what happens if the Fan Belt (alternator belt) breaks?

How long have you got before the Engine dies or Starts to Overheat.

So you're out for a nice long drive and the Fan Belt Breaks, what is the best thing to do.

Do you call out the breakdown truck or would you be able to fix it at the side of the road.

Should I carry a Spare Battery and Fan Belt.

 

my fan belt snapped whilst driving, fortunately I was only 5 miles from home, managed to drive home, switched off every electrical load possible.
(belt that drives mechanical fan doesn't drive alternator on my model)

fixing at the roadside would I think be quite difficult.

on my 6.0L the "fan belt" (alternator) is closest to the engine, meaning three other belts in front have to be un-tensioned and removed to allow the alternator belt to be replaced.

I watched a mechanic spend three hours to replace mine, granted he had never worked on XJS V12 before, some belt tensioners were accessible from above engine, others required car up on lift for easy access.

After observing the work I thought £80 labour charge very reasonable (2015 price)

 

What drives the water pump?

 

The water pump is driven by the same belt as the PAS pump.

 

Hi Paul_59

I wouldn't have a problem Changing the Belts at home even if it took a day or two but in the event you are out for a drive, then I would imagine its a very different story.

I was thinking that the extra load on the Alternator when using 'efans' could be one of the downsides.

 

Changing an alternator belt by the roadside is impossible OB. As Mikey indicated, the water pump is the most important. If the alternator belt breaks (which it will not if you religiously renew the belts every 5 years - and probably not if you do not) you will get home fine, unless you are trapped in a 50 minute traffic jam. If it ever happens, turn off everything that uses juice (aircon - interior fans, radio, lights, etc) and drive home. The battery will have enough juice to keep the ignition going (your real worry) and if the thermostat activates the main fan (unlikely if you are moving faster than 25MPH), that too. I mean, what would you do if the mechanical fan belt breaks? Or the water pump? No real reliability difference. I do though, always carry a set of spare belts, as in any event, whatever breaks, you will be able to get to the nearest garage!
Greg

 

Hi Greg

Cheers!

That sounds good advice, its just for me that 'efans' are a step into the unknown.

Also wondering what to do when I take her for an MOT as Garages seem to have a habit of wanting to keep the Engine Running even when there's no need.

Should I keep one of the 'efans' running, after I switch her off to cool her down?

 

Why? See other thread about electric water pumps.

 

Hi Mikey

Because the Engine Starts to get Hotter when you Switch it off.

 

Yes, it's called soak back. It's not the 'engine' getting hotter, just the coolant trapped in the area near the temp probe. Not a problem.

 

@OB

Technically the altenator doesn't power anything, other than charge the battery. MOST cars drain the power they need directly from the battery, which is constantly being fed with ~13-15V where as the car has a fixed 12V power supply. Electrical fans will do no harm to the altenator... You can always upgrade to a more powerful one, but then again: how often will the fans be on? Iirc the airflow at 20 mph is more than enough to cool the engine without any fans on... See what Greg wrote a few weeks ago regarding his fans.

No worry about anything OB, it'll be just fine

 

Hi Mikey

If that's not a Problem, then why did they fit the XJS with an Auxiliary Cool down Fan that runs for about 10 Minutes when the Engine is Switched OFF.

 

Good question because all it does is cools the fluid in the radiator, not in the engine. The pump would have to be operating to cool that.

 

OB, a failed alternator is not an issue with efans, I had my alternator fail about 200km from home and I got home ok (after a jump start) it was raining so I had the wipers on but had to switch off the headlights, my car has dual efans from a Ford.

You 90 XJS will have a serpentine belt for the ALT so less likely to fail than a V belt. I would check the belts every time you service as a matter of course.

 

Hi Warrjon

Cheers!

Are both your efans wired to come on when the ignition is on?

Or how is the Second Fan Wired.

 

No the RH fan is wired to come on with the ignition and the LH fan is wired to the original auxiliary fan wiring so it comes on with the thermo switch.

 

Hi Warrjon

Cheers!

Just what I wanted to know.

When I was wiring my Stereo, there was a live feed to it when the Ignition Switch was turned on, would this be a good place to take an (ignition switch) controlled feed to the 'efan'?

 

My fans do not come on with ignition on Accessories position 1 - they are wired to come on with ignition in position 2. So I can run the stereo without the fan running.

 

Good point Warrjon

I think I remember another wire for the Stereo that did that.

 

i have been driving for 65years , and i can only remember 1 time a belt slipped off a pulley, never had a belt actually break in pieces!!

and have owned over 100 cars!

lot of ink here?