Radiator Fan switch

[928cdu]

Hi all,
I originally fitted my car with an electric fan & a manual switch, which goes on when temp gauge creeps up above normal (IE: in traffic) .

Last night I forgot & nearly got caught out, fortunately needle returned to normal when I flicked on the fan.

So I will now get an automatic switch, lesson learned !

Any recommendations ? I'm thing of an an adjustable capillary type commonly found on ebay for £18ish delivered.

Also have seen some top hose in-line one (more expensive) where you have to doctor the top hose, but they are fixed temperature. 80-90 degrees.

Any thoughts or other options ?

Thanks ..

[greyV8pete]

Re: Radiator Fan switch

Hi all,
I originally fitted my car with an electric fan & a manual switch, which goes on when temp gauge creeps up above normal (IE: in traffic) .

Last night I forgot & nearly got caught out, fortunately needle returned to normal when I flicked on the fan.

So I will now get an automatic switch, lesson learned !

Any recommendations ? I'm thing of an an adjustable capillary type commonly found on ebay for £18ish delivered.

Also have seen some top hose in-line one (more expensive) where you have to doctor the top hose, but they are fixed temperature. 80-90 degrees.

Any thoughts or other options ?

Thanks ..

Have a look at the following:

https://www.carbuildersolutions.com/uk/adjustable-fan-controller-thermostat

I fitted one of these to the second rad on my Hunter and it works well. The capilliary tube is very fine stainless so it will fit between the top hose ant the rad spigot without needing a special fitment to seal it. That said I have fitted the sensing probe between the fins on my rad so no draining down required. Peter.

[stevejgreen]

Re: Radiator Fan switch

Invest in a radiator with an extra core, it might even be cheaper than messing around with pipework and thermostats.
An electric fan is only really useful in slow or static traffic where you have no extra airflow from your forward speed, but a reworked radiator still has benefits in really hot weather.

More information and my thoughts can be found at https://kvisit.com/S9dPbAw

[andyf]

Re: Radiator Fan switch

If you wan to fit a fan switch I would consider one of these http://www.demon-tweeks.co.uk/motors...fan-controller

[scott h]

Re: Radiator Fan switch

I am currently rebuilding my Berlinetta. When it came to controlling the electric fan I decided that an adjustable switch would be too tempting to adjust all the time. I went for an in hose adapter that fits a standard fan switch. These switches are available in various temperature ranges. So I chose one that would come on a bit above the fully open temperature for the thermostat. I also fitted a manual override switch. All the parts are easily available from the likes of Car Builder or ebay.

[lil_red_roadster]

Re: Radiator Fan switch

I am currently rebuilding my Berlinetta. When it came to controlling the electric fan I decided that an adjustable switch would be too tempting to adjust all the time. I went for an in hose adapter that fits a standard fan switch. These switches are available in various temperature ranges. So I chose one that would come on a bit above the fully open temperature for the thermostat. I also fitted a manual override switch. All the parts are easily available from the likes of Car Builder or ebay.

Likewise...I'm rewiring my Roadster & whilst I did have the ECU controlling the fan there was no override...plus I'm also planning ahead to doing away with the ECU going back to a tuned B series, so wanted to future proof. In the short term I may use the ECU control to power a bilge pump to suck cooler air up to the inlet (which suffers from being near the bulkhead).

[tony.branson76]

Re: Radiator Fan switch

I have had 2 of the capillary type switches fail. On the B series one I replaced it with one of the in-hose switches. More expensive and not adjustable but hopefully more reliable. On the O series the bulb had come off the capillary bit and is still somewhere in the radiator header tank. The hose isn’t as suitable for the in-hose variety so I have just used another capillary one still working as I write. There is a Lug on the cylinder head just below the temp sensor for the fuel injection ECU which probably could be drilled and tapped for a switch, however I think the best solution is a suitable fitting high in the radiator, project for the future. I do have an override switch on both cars.

[greyV8pete]

Re: Radiator Fan switch

I have had 2 of the capillary type switches fail. On the B series one I replaced it with one of the in-hose switches. More expensive and not adjustable but hopefully more reliable. On the O series the bulb had come off the capillary bit and is still somewhere in the radiator header tank. The hose isn’t as suitable for the in-hose variety so I have just used another capillary one still working as I write. There is a Lug on the cylinder head just below the temp sensor for the fuel injection ECU which probably could be drilled and tapped for a switch, however I think the best solution is a suitable fitting high in the radiator, project for the future. I do have an override switch on both cars.

The thermo switch needs to be on the radiator side of the car’s thermostat otherwise it will switch on when the engine warms up, even with a cold radiator. Peter.

[andyf]

Re: Radiator Fan switch

I have an adaptor in the bottom hose with a standard M22 switch that turns on at 92 and off at 86 with a thermostat that is fully open at 82. The Viva rad I marginal so I have a project in planning to get it recored, I did this for the rally car ad it made a big difference.

[stevejgreen]

Re: Radiator Fan switch

I am not sure that the location of the thermostat is critical, especially if it's adjustable and located in the coolant stream.
If a temperature sensor is going to be connected into an ECU that controls ignition timing, fuel mixture etc. Then location becomes critical as does the calibration of the ECU.

Simply turning a fan on and off at a temperature based on an uncalibrated temperature sensor, driving an uncalibrated gauge, both supplied by a Marina style voltage regulator that is in essence an uncalibrated bimetallic switch, is hardly an engine critical function.

Marina based Roadsters have a demonstrable history of overheating, an unmodified Viva rad, from a 1.2 engine, will always struggle to cool a 1.8 engine. With an extra core the problem is virtually eradicated, and is not dependant on gauge watching or secondary thermostats etc.

The other problem when the car is in motion is that the air will take the easy route through the grill and then above or below the radiator where there are large gaps, rather than through the radiator where it will do some work.

[andyf]

Re: Radiator Fan switch

Mie is fine when making progress I only have issues I traffic, but then I'm being a perfectionist as the temperature only gets to just over 90 rather than being close to the idea 80 for a pinto

[928cdu]

Re: Radiator Fan switch

Thanks for all the replies , all good points..

My car only has a 1200cc Triumph engine, cooled by a Gt6 rad (perfect shape for the Marlin BTW), so with adequate airflow cooling is no issue. So I've decided to go for a capillary switch to start with & upgrade to some of the other suggestions should that prove problematical.

Several of you talk of an override switch, (possible stupid question coming up ) do you wire it to force the electrical fan "on", or "off". I guess to force "on" is more useful ?

[h_m_cumming]

Re: Radiator Fan switch

I've had a capillary one in for the last 20yrs without trouble. Make sure you wrap some rubber round the tube before clamping it so that it is not against the hard rad. tube.
The over-ride switch is wired across the capillary switch to by-pass it when you need some extra cooling, mainly if caught in stop start traffic.

[Gareth]

Re: Radiator Fan switch

I tend to agree with Steve's last comments. I've just got a pull switch on the dash and when the going gets tough, I pull it. Simples. And cheap.
But then, I'm old fashioned!
Gareth.

[listerjp2]

Re: Radiator Fan switch

I had a capillary one and it worked for over 60,000 miles including trying to keep up with the V8 lads up in Scotland while doing the le jog run at knocking on 100mph. No switch just used the auto set.