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Revotec EFC - click for larger size

Electronic Fan Control (EFC) & Silicone Hoses

August 2006 (Correction)

During a hot spell it was noted that the temperature gauge frequently approached the 100°C mark before the cooling fan cut in. There was no evidence of boiling or losing coolant (and the gauge may not be completely accurate) but I felt that the fixed fan sender was not sensitive enough.

I decided to fit an adjustable Electronic Fan Control (EFC) which I hoped would enable me to moderate the engine temperature. The (28mm) Revotec EFC unit (available from Europa) fits ‘in-line’ into the top hose instead of the ‘standard’ sender which was fitted into the bottom hose. I also decided, as there would be some hose changes anyway, to fit silicone hoses throughout the cooling system. The original hoses (as supplied by NG) were of ‘unknown’ origin; at least I do not know what vehicle they are made for.

Electrical connections

EFC modified wiring - click for larger size The Revotec unit comes complete with a relay and wiring and it should be noted that “Failure to use the EFC with the included relay or modification of the wires in any way will invalidate the warranty.” However, I already had the ‘standard’ NG fan relay fitted under the dash and wished to use as much of the existing wiring as possible, so I decided to make the neatest job I could and therefore used only the EFC and discarded the rest.

The Revotec EFC itself has three wires attached which need to be connected as follows (see diagram):
  1. a red wire to connect to a 12v supply
  2. a blue wire to connect to the relay on the ground trigger side (usually terminal 85). This is pulled down to earth through the fan control (when the engine is hot) to switch on the relay.
  3. a black wire to connect to earth.
The two existing wires to the fixed fan sender (black/orange, black) correspond to the EFC’s blue (no.2) and black (no. 3) respectively and these can therefore be simply re-routed back to the new location (top hose) and connected to the EFC. A new supply wire was run from the starter’s main terminal via an in-line fuse to the EFC’s red connection (no. 1). As this is always live (with the battery cut-out switched on), the fan can continue to run after the ignition is switched off.


Click here for PDF version of EFC Wiring

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Plumbing

EFC & top hoses - click for larger size Silicone hoses (available from Europa, for example) are available in various sizes and standard bends, etc. The sizes here give an indication as to what is needed. The EFC (28mm) is the same diameter as the thermostat outlet and a 28mm 90° elbow (4” legs) can be cut down to fit. The radiator inlet is a little larger at 32mm, so a reducer (32 to 25mm) was cut down to connect the EFC to the radiator.

Silicone bottom hoses - click for larger size For the bottom hose, I obtained the metal elbow (ACH5031) and adaptor (AMK8847) as used on earlier MGBs to remove the need for a bottom hose with a ‘T’ in. I then used a 32mm 90° elbow (6” legs) cut down to connect the radiator to the elbow and part of the piece cut off to connect the elbow to the water pump inlet. The remaining 3 hoses (elbow to heater return pipe, heater supply, heater return) were cut from straight 12.5mm silicone hose. Stainless steel hose clips were used throughout.

I am now able to adjust the point at which the fan cuts in and thus improve the running temperature of the engine. For a sequel, see Thermostat in the Repairs section.


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