Kenlowe Cooling Fan switching on and staying on all the time (Triumph Spitfire Mk III)

[keithhale]

Just a quick question if anyone can point me in the right direction. When I turn on the ignition the Kenlowe Fan comes on and runs all the time, whether the engine is cold or hot. It turns off when I take the ignition key out. I'm worried that it is draining the battery so would anyone have an idea where I could start to look at causes, or solutions? Many thanks.

[Howard]

There should be an adjustable thermostat near the radiator to control the fan. If this has been set at low, the fan will run all the time the car is running. Kenlow recommend that the fan comes on when the gauge is showing about 3/4 of maximum, but personally I set it at about 1/2.

If you get stuck I should be able to find some more data on the wiring

H

[keithhale]

Thanks Howard, I'll look at that and see if that helps. I appreciate the offer of your help which is much appreciated. 

Keith.

[DVD3500]

There are aftermarket mechanical i.e. bi-metallic switches you can fit to any electric fan. They come in a range of temperatures (on and off temps) and are usually shaped like a pencil, maybe 2-3 inches long.

I did it on my Porsche 924. The official temperature switch was Porsche-Price so I got the switch for likely 5 of my favorite currency back in the day. Wired the fan up and stuck it as close to the return i.e. coming from the motor aka hot hose as I could in the radiator.

Worked a charm!

[Tim Bancroft]

Alternatively, have the radiator modified with a boss that can take a fan switch, then wire in a small circuit with a switch in the cockpit. Fan switches can be obtained in various temperature ranges. Best of both worlds as one can just leave for the fan to be switched on auomatically or alternatively one can over-ride and switch the fan on when harder driving is about to be done.

[Martins Stag]

I ran my 2.5 Spitfire for a number of years without a electric Thermostat and just used a manual switch and just kept an eye on the temperature gauge and turned it on as necessary.... 

Just a thought 

Martin 

[ferny]

Fiesta (of some mk) have a thermostat housing with a sensor which fits. Look on eBay for suitable. 

[Guppy916]

I had a similar problem last year, mine won't come on not matter what I did, after all the usual checking I purchased a new relay from eBay 

https://www.ebay.co.uk/itm/174515829414

and the problem was solved,  fan now works fine I think I paid £5 

[standardthread]

16 hours ago, ferny said:

Fiesta (of some mk) have a thermostat housing with a sensor which fits. Look on eBay for suitable. 

Try one of these;

https://www.ebay.co.uk/itm/Stoney-Racing-Universal-Radiator-Fan-Switch-Adapter-Temperature-Sensor-Cooling/282802366937?epid=14012614545&hash=item41d855a9d9:m:mOyIuSif4F5SJmogqZGJEeg&var=582118473360

I got one for my Dolomite. I couldn't use the rad filler plug for a sensor, the previous owner had modified it so I fitted one of these in the return pipe with a stat opening at a lower temperature

 

[Adrian Girling]

Spotted this post as I'm thinking of fitting an MX5 fan (which I have) and need to work out how to switch it on and off.  My solution would be fairly simple electronics to sniff the voltage at the temperature sensor which I believe is an NTC thermistor and use a comparator and a relay to turn the fan on and off.  Slightly more complex to add hysterisis so it doesn't hunt, and a way to leave it running after the ignition is switched off until a lower temperature is reached (as the temperature would otherwise go up for a while)

Surely, there is a product out there that does this?

[Clive]

6 minutes ago, Adrian Girling said:

Surely, there is a product out there that does this?

KISS

Just fit a proper OE type switch to top or bottom hose, and use an inline hose adapter.

Or get a boss for a switch fitted to teh rad.

MGs and Minis used a fan swith that seems to involve a simple hole in the header tank of the rad, and a rubber grommet to seal it. I had to fit a new one to a family members MGB years ago, I was surprised by how simple it was, and teh fact it worked!

[glang]

I used one of these with the sensor pushed into the radiator fins. Works perfectly...

https://www.ebay.co.uk/itm/363880767253?hash=item54b8fbdf15%3Ag%3AKboAAOSwm21iKPSF&LH_ItemCondition=1000

[RobPearce]

1 hour ago, Adrian Girling said:

to sniff the voltage at the temperature sensor which I believe is an NTC thermistor

It is, but the circuit is driven from a "voltage stabiliser" that may (if it's still original) be anything but, so the voltage you'll see will be chopped and horrible. If you're determined to do something overly complex, then you'll need to add your own NTC thermistor with a supply you're in control of. Otherwise, see replies from clive and glang above.

[Adrian Girling]

Wow, I hadn't expected a storm of discouraging responses.  I've switched to an alternator as the "voltage stabiliser" was defunct, but I'd probably incorporate a cheap (£0.50) linear voltage regulator anyway for good practice.  I disagree that this is "overly complex" - simple to do and there must be a reason all modern ICE cars have something like this.  Adding extra sensors is more complex in my view

[glang]

Ha, if you think thats a storm try asking if an electric fan is necessary or whether fuel additives work or even better the benefits of 'silicon' brake fluid😂

Edited July 7, 2022 by glang

[Rosbif]

Just now, glang said:

Ha, if you think thats a storm try asking if an electric fan is necessary or whether fuel additives work😂

Is it? Do they? 😁😉

I'm going to keep my head down now  . . .

[drofgum]

Adrian,

The device you are calling the voltage stabiliser is actually the voltage regulator. That controlled the output of the old generator. The voltage stabiliser takes the system voltage and turns it on and off to give a resulting average voltage of 10 V. That gives a stable average voltage for the temperature and fuel level gauges. The pulsed nature of the voltage to the temperature sender would make it a difficult signal to use as you intend for fan control. There are electronic versions of the voltage stabiliser that don't pulse the power, but rather electronically reduce their output to a steady 10 V.  Using one of them would make your idea easier.

Regards,

Paul

[Adrian Girling]

Wow, at least I'm getting a lot of responses, got to look on the positive!

Trying to reply to more than one post, don't think I can quote from more than one at a time:

Thanks Paul.  I can see that the voltage regulator would be lumpy - hence the idea of putting a linear voltage regulator IC between the positive rail and the temperature meter to clamp it to 12V.  LM1085IT-12/NOPB has a very low dropout voltage, or even LM317T which would allow adjustment to 10V or lower.

Thanks Glang, I'll check out the posts on whether an electric fan is necessary! Almost certainly not, but I'm enjoying messing around whilst I wait for other parst to be delivered....

 

[RobPearce]

19 minutes ago, Adrian Girling said:

LM1085IT-12/NOPB has a very low dropout voltage, or even LM317T which would allow adjustment to 10V or lower.

Are you an electronic engineer?

The voltage stabiliser for the gauges was originally, as Paul and I both said, a switching device, which means the voltage on the sender is a mess. If you replace that stabiliser with an LM317T set to 10V, then that problem is avoided. However...

2 hours ago, Adrian Girling said:

simple to do and there must be a reason all modern ICE cars have something like this.

Modern cars absolutely DO NOT have something like what you propose. They essentially fall into two categories:

- Those which have independent temperature senders for the gauges and for the ECU (which controls the fan), like Clive, Glang and I all suggested

- Those which only have one sender but it feeds the ECU only, and the ECU drives the gauges with a PWM output

Surely there must be a reason for that. Having worked in the field for thirty years, I rather suspect it's similar to my reasons for not adopting the approach you propose.

[Adrian Girling]

31 minutes ago, RobPearce said:

Surely there must be a reason for that.

Because it's cheaper and easier to do if you are starting from scratch and have an ECU.  As an engineer for over 50 years I had a successful career challenging the status quo.  One thing I learned early on is not to trash other peoples ideas - we make progress by considering new ways to do things, even if they are not worth pursuing, as they may lead others to ideas which are. There are better more courteous ways of presenting your point of view.

I am not proposing a linear voltage regulator to replace the "voltage stabiliser" or "voltage regulator" whichever you choose to call it.  Probably more accurate to describe it as a voltage regulator as pointed out by Paul (drofgum) as that better fits it's actual function.  I am proposing inserting the the IC beteen the positive rail and the temperature meter - it would not handle the current for all the electrics.

[RobPearce]

35 minutes ago, Adrian Girling said:

One thing I learned early on is not to trash other peoples ideas

The flip-side to that is to listen to other people's objections to your own ideas. I have stated my objections and you seem to be flatly dismissing them without consideration.

37 minutes ago, Adrian Girling said:

I am proposing inserting the the IC beteen the positive rail and the temperature meter

To what end? And in what way does that address the issue I raised?

If you are monitoring a voltage from a potential divider (and that's essentially what you propose, since the sender is a variable resistance and the gauge is a roughly fixed resistance) then it's essential that you compare it with the correct reference, which must be referenced to the top of the divider. Since I've pointed out that you have no control over that top point, you need to reference it. And if it's the toggling bimetal strip type, then you need to check when it's too small to be a useful reference and "gate" your decision based on that. This makes for a complex circuit.

 

[standardthread]

Gentlemen, members of every profession have their own opinions and ways of doing things, research and development are great tools. Each to their own. This is, after all a hobby.

Now the grenade!!!

Fitting an electric fan? Economy, saving the planet, less cash spent on petrol et al

Edited July 7, 2022 by standardthread

[glang]

All hokum and balderdash! Mechanical fan has nothing to go wrong and was designed by Triumphs finest so must be sufficient for cooling🤔

[Adrian Girling]

1 hour ago, standardthread said:

Gentlemen, members of every profession have their own opinions and ways of doing things, research and development are great tools. Each to their own. This is, after all a hobby.

Thanks for this, needed someone to remind us

1 hour ago, standardthread said:

Fitting an electric fan? Economy, saving the planet, less cash spent on petrol

And helping the engine to run at the optimum temperature in a world where more time is spent in traffic jams.  When this car was developed I believe there were less than 10% of the cars on the road than there are now.

 

17 minutes ago, glang said:

Mechanical fan has nothing to go wrong and was designed by Triumphs finest

Agreed that it's simple and Triumphs of that era were great - modern cars have far more things to go wrong!  I was present, visiting the Truimph factory when the Lynx was cancelled because "it would have competed with the Rover 2000" and everyone walked out. I was witnessing the implosion of the British motor industry. 

[Rosbif]

28 minutes ago, Adrian Girling said:

where more time is spent in traffic jams.  

You're driving on the wrong roads in that case. 😃

In my case a traffic jam consists of 2 cars following a tractor and trailer for 1 kilometer.

There is even a town 45 minutes away where a classic car club now creates a traffic jam once a year to recreate the 60s/70s.