Installing an Electric Water Pump

The more power you want from the engine, the better the cooling system has to be. This project is to replace the Thermostat system with a computer controlled electric water pump. I have chosen to use the Davies-Craig EWP1 (now an EWP80) pump and controller.

2.0L, 2.2L & 2.4L Cooling System Differences

When the 2.2L (2.4L) engine is cold, the thermostat is closed and the water re-circulates around the engine, via the thermostat housing, and does not go through the radiator, this warms the engine quicker. (This is why the 2.2L (2.4L) thermostat housing is so complicated, with the hose from the bottom of the radiator going via the thermostat housing to the water pump inlet). As the engine warms up, the thermostat begins to open, the engine re-circulation system starts to close, and water starts to go through the radiator. As the engine temperature reaches its running temperature the thermostat is fully open, the re-circulation system is closed, and all the water flows through the radiator.

In the 2.2L and 2.4L engines, the water re-circulation system must be permanently closed , and the thermostat removed, for the electric pump and its controller to work properly. In the Ascona/Manta 2.0L (and below) engines, only the thermostat needs to be removed.

The electric pump works by speeding up the pump as the water temperature climbs above the required operating temperature, and slows the pump as the temperature falls. This will mean that the engine will take longer to warm up from cold, but temperature control should be much more precise.

Gallery - Electric Water Pump

Installing the Electric Water Pump on 4 and 6 Cylinder CIH engines:

Note: If you are still using the original mechanical radiator fan, this must be replaced by an electrical fan fitted directly to the radiator. An electric radiator fan can pull, or push, much more air through the radiator and is therefore a much better aid to engine cooling.

With 2.2L (and 2.4L) engines, first we have to remove the engine water re-circulation system which is part of the standard thermostat housing. This can be done by inserting a plug into the casing where the lower plate of the thermostat was located (see pictures). In the picture shown, we used a threaded alloy plug, but a tapered press fit plug could have been used. The re-circulation system is now permanently closed off. The lower section of the thermostat housing can now be cut off, as there would be no point pumping water from the bottom of the radiator (via the new electric pump), up through the thermostat housing and then back down to the old mechanical water pump inlet.

Note: It would be quite reasonable to leave the water pump intact, because the pump impeller will free-wheel (it must not be driven by the fan V-Belt), so allowing water to pass through it. I decided that I wanted to ensure that the new electric water pump had as few restrictions to pump against as possible, so reducing current usage, maximising water flow, and giving maximum reliability to the system.

The water pump impellor was removed using a puller. The pump shaft and bearing were pressed out of the pump housing. The pump bearing housing was then cut back on the inside of the pump housing using a milling machine, to allow free flow of water from the pump inlet into the engine block. A tapered plug was then pressed into the hole left by the pump shaft and bearing, from the inside. A second smaller plug was pressed into the drain hole for the pump water seal. The front of the water pump housing was then milled back to remove the protruding part of the pump bearing/seal housing.

The original fan V-Belt had to be replaced as there was no water pump to be driven (Note: Also required if pump left intact). A 763mm belt fits perfectly.

The electric water pump was located near the bottom outlet of the radiator, just above the anti-roll bar. The pump outlet was then piped up to the mechanical pump inlet.

The electric water pump controller is located inside the passenger compartment. Since the controller has a temperature adjustment it must be put somewhere accessible. In the case of my car, it is located where the ashtray used to sit. The cable for the temperature transducer is long enough, so that it could have been fitted in the glove box, if required.


I am now able to control the water temperature from as low as 71°C. For maximum power, the water temperature should to be kept at or below 80°C in the CIH engine, which we found while testing on the rolling-road at Emerald Cams in November 2000.

I still need to use the electric fan for long periods at tick-over, but normal operation should be much better than with my previous engine.