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A glorious drive to a show on a long, summer day is the reason why many of us own the classic cars that we do.
Yet that very weather can cause older cars to get hot under the collar. Most engine-driven fans run unnecessarily for 80% of the time. The ram-air effect when you’re moving is enough to keep your car from boiling in most instances.
But if you get caught in a tailback or face a long climb at low speed, the temperature needle will begin to rise as the mechanical fan slows when your speed drops.
Converting to an electric fan or fitting a booster provides peace of mind. These devices sense when the motor gets hot and don’t need revs or motion to cool it in heavy traffic. They also free up a few bhp if you remove the mechanical fan.
Kits are available to replace the engine fan or to allow it to be kept while an auxiliary unit is attached to cut in when necessary or with manual override. Kenlowe is the best-known name in the market, but it now has various rivals.
Recent developments mean that the old-type, ‘probe in the water’ sensors are outdated. Some models can now be operated at two speeds, automatically, to cater for every situation.
1: MEASURE UP
You should aim to squeeze the largest fan possible into the space that was occupied by the engine fan.
Your best option is to take the car to your stockist to check that the dimensions work, or measure and draw a diagram with accurate clearances.
Space was tight here, so we chose an auxiliary fan.
2: STRIP DOWN
3: DRAIN AND REMOVE RAD
Empty the coolant into an old bowl for environmental disposal if it’s more than a year old. If it’s younger, save it for re-use.
Then refer to your manual or handbook to disconnect and remove the radiator.
It’s heavy but fragile, so be careful not to bash or catch it on anything as you lift out the unit.
4: ATTACH FAN TO RADIATOR
Some kits come with these zip-fasteners to pull the housing against the radiator matrix. Others use nuts and bolts.
Be cautious when sliding them through the heat-evaporating gills between the tubes because they’re also delicate. Plus, you won’t discover you have a leak until it’s all back together.
5: INSTALL THE SENSOR
New technology does away with top-hose sensors and replaces them with an aluminium probe that sits between the rad’s cooling tubes.
It’s permanently wired to the relay switchblock and must be fitted close to the top-hose entry. Again, insert it gently and secure if necessary using the clips provided.
The new relay plate and pre-wired block is simplicity itself to fit. All of the connections into the controller are here.
Follow the colour-coded wiring diagram and make sure that you’re on the positive- or negative-earth page, depending on your car’s electrics. The tiny white circle is the equivalent of the C-N-H knob.
7: AN OVERRIDE SWITCH
The wiring diagram shows how to connect an optional override switch and warning lamp.
You’ll need to buy them from a motor factor, but fitting one in the cabin will provide reassurance should you approach a jam. It means you can switch the fan on before the gauge moves above ‘normal’.
8: CHECK THAT IT WORKS
Once everything is in place, review each connection to ensure that it is correct.
Then run the car up to temperature and let the instrument needle creep above ‘N’. The fan should cut in just below halfway between ‘N’ and ‘H’ or the red zone.
Minutely adjust the white controller to alter the setting.