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Kenlowe Fan stops my engine!


haggis
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Hi, and thanks, idle speed good before the fan kicks in, normally around 900/1000 RPM, I have actually tried setting it a bit higher but the engine still dies. Its got an alternator and elec fuel pump, wondering if my alternator should be a bit juicier?

 

hag

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Hi, how long has the fan been fitted?  Was there a period when it was all working fine?  Have you checked the wiring, and is it fused?

 

The draw of an electric fan should not be too much for the average alternator, particularly as I imagine the fan is less likely to be activated when there's other current being drawn such a headlights.

 

Tom

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Hi and thanks for all the responses, I've just been out and checked and it looks like its connected to the existing loom, utilising the Green/White wire from the front indicator for its power!, which should mean its not from the ignition (as in principle, the indicators only work when the ignition is on), but i will check this. I have no idea when the fan was fitted it came with the car, which I've had less than a month, which has a lot of issues!  Sounds like I should wire it straight from the battery with an inline fuse of 30Amps. Being a bit special when it comes to electrics, I'm assuming a 5amp cable won't be sufficient?

 

Hag

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To calculate what rating cable to use you need to divide watts by volts. So if the fan draws 60 watts (you'll need to check yours), divide by 12(volts), that gives you 5 (amps). I would use a cable & fuse rated a bit higher than whatever it calculates to as there will be a bit of a surge upon start up.

 

Personally I would add a relay and power direct from a fused permanently live supply.

 

Everything you might need is available from www.autosparks.co.uk 

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Disconnect it from wherever it is connected, and try a direct supply from the battery. As Darren points out, that will tell you if the wiring is the problem. 

 

Almost any alternator 25A and above is ample (ha ha) for these cars unless you add heated rear window/heated seats etc etc or, of course, an array of spotlights for night rallies.....

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Thanks for your help Darren, and for the link, great site. I'll give your suggestion a go as its the best I got to go on and makes sense, just checking does the permanent fused live supply mean it will run on after the ignition is switched off? 

 

hag

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Hello Hag.

 

The attached may help - I did an article on electric fan conversion for my local classic car club newsletter.

 

If you want to run the fan after turning the engine off, then wire to the live side of the fuse box.

 

Hope it's useful ??

 

Regards.

 

Richard.

Electric Fan Conversion Diagram.pdf

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Hi Richard, thanks for the diagram, there are so many on the internet and none of them seemed relevant, managed to wire a new relay and get the fan working again just need a test drive to see if its one of my problems solved. Its just off then on now.

So many problems, so little time. (trying to get to SEM next Sunday)

 

Thanks

Hag

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Hello Hag.

 

No problem, you're welcome.

 

That is how I wired the electric fan in to my Vitesse last year and all is fine.

 

I'm sure it's obvious but worthy of note: an electric fan on start-up pulls a greater amperage then when it's settled & running.

 

Therefore, if you are running a 80watt fan then 8amp cable is the ABSOLUTE minimum to use. The Vitesse runs with a 120watt fan and have to use 17.5amp cable and IMHO it's worth using this amp cable for a 80watt fan.  The cable spec for 17.5 amp is 28/0.30 whereas 8amp is 14/0.30 

 

Worth thinking about.

 

Good luck.

 

Regards.

 

Richard.

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I have a similar issue with my Spitfire 1500.  Idles at about 1000 rpm, purposely set high, but when the  Kenlow fan cuts in the idle speed drops to about 500 rpm requiring an occasional prod of the accelerator to ensure that it does not stall.  The fan is wired via a relay and fuse directly to the battery using wire rated at approximately 20 amps.  The alternator is rated at 45 amps.  I came to the conclusion that it is the extra load  on the engine as the alternator is forced to supply the additional current that slows the idle speed.  You also get a lowering of the idle speed when you switch on the headlights which supports this theory.  The battery turns the engine over vigorously when starting so this would suggest that the battery is not at fault.  The only remedy is to pull the chock out about 1/4" so as to increase the idle speed without enriching the mixture. It is not much of an issue as I do not frequently drive in heavy traffic, preferring the open country roads around where I live.

 

Graham

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Hello Graham.

 

I would be interested to see what the alternator is pushing out, via a multi-meter, with no load (within reason) from any electrical unit - lights / electric fan / blower etc.

 

Next I would turn on 1x electrical unit - lets say lights and see what the voltage drop is. The alternator in good working order should be able to recover this load.

 

As each additional load is applied note the voltage drop and see how the alternator copes.

 

It is possible that the alternator is healthy enough to deal with minimal load but nothing greater - if this is the case then I would suspect the alternator is on the way out.

 

Needless to say all wires and connections have to be checked prior to doing this investigation - for obvious reasons.

 

With regard to the choke action, the very fact you are pulling the choke out to raise the idle speed is enriching the mixture automatically. 

 

As you say the battery is fine and that is because the alternator still has the capacity to do this job - it will be a different story if it has to juggle lots of additional electrical load and charge the battery at the same time; which of course it has to !! 

 

Just some observations.

 

Regards.

 

Richard.

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  • 4 weeks later...

Hag

 

I've just replaced the fusebox on my GT6 with an Autosparks 16 way box. A very worthwhile upgrade. I checked the current draw on each of the major components with a DC clamp meter. My electric fan and water pump draw 13A. You only need to size the supply cable to cope with the running current not the startup current. The spike at switch on is termed the mag inrush current. It only lasts for a few milliseconds and does.not cause any damage to the cable insulation.

Power it via a relay as.has been suggested and power the headlights through one as well while you're at it. The master light switch isn't really up to the job and will cause dim headlights after a while.

 

Cheers

 

Alan

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HI everyone, thanks for all your posts, I've only just managed to sign back on to the Forum as I forgot my password. I will definately fit a relay to my headlights and I added a reverse light which I'm sure could also do with one as well. The good news is the relay was a great success I used an 8amp cable and wired direct to the battery and result, the idle does drop slightly when the fan kicks in but she keeps on running :) but I have some more serious engine problems to deal with now. :(

 

Thanks for all your help.

 

Hag

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