Modifying the Westfield Cooling System.

Overview

Photograph, courtesy of Tim Hoverd

The modification of the Westfield cooling system looks straightforward at first glance.  “Tee Piece solutions are quick and easy to implement (See photograph right) but suffer from excessive expansion and possible overflow of the header tank.  This is probably caused by coolant from the thermostat bypass and heater coolant competing to use the same pipe.  The pipe diameter is insufficient to sustain the volume and flow rate required.

The provision of a separate bypass pipe, as used in the Ford Mondeo, is the recommended solution. This avoids the excessive expansion problem. The relative diameter of the thermostat bypass pipe, to the alloy pipe running from the thermostat outlet to the radiator top hose is important.  We recommend 16mm, ½” bore pipe as giving adequate flow before the thermostat opens and minimal bleed across the engine once the thermostat is open. Expansion in to the header tank will still take place but this is normal, and it should not overflow. Any excess coolant will be ducted via the overflow pipe back to the radiator. 

The principle of modifying the Westfield cooling system is the same for non-ducted and ducted nose. Ford 2.0Ltr and 1800cc variants. There are detail differences but two common alterations need to be accomplished on each.

1.            Connect a new bypass pipe from the thermostat housing to the Radiator bottom hose

2.            Blank off the old bypass connection in the alloy pipe to the top hose.

Zetec 2.0L Water Pump  Inlet

The simplest solution would be to replace the water pump inlet pipe with one that has a branch in it, to permit connection of the bypass pipe.  However it is not possible to implement a single solution, due to differences in the angle of the water pump inlet on 1800 cc and 2.0 Litre engines. The photograph (left) shows that the inlet on the 2.0 Litre Zetec is angled back towards the exhaust system.   Despite extensive research no suitable replacement for the water pump inlet pipe could readily be found.  

Photograph, Courtesy of Steve Richards

The water pump inlet on the 1800 is at right angles to the engine cylinder block, and a modified pipe from a Mondeo can be used, as shown on the right.  For this reason the modification of the cooling system is sectioned in to two.

1. Ford Zetec 2.0 litre, ducted and non-ducted nose, using a modified Alloy pipe.
    
2. Ford 1800 Zetec, ducted and non-ducted nose, using a modified Mondeo Pipe.

Zetec Water Pumps 

Westfield Auxilliary Drive Belt	Diagram, Courtesy of Haynes Publishing

The Ford Mondeo auxiliary drive (serpentine) belt drives the water pump (7), power steering (1), air conditioning compressor (5) and Alternator (3) from the crankshaft pulley (6) as show in the diagram above right. From the Diagram if the crankshaft pulley rotates clockwise, the water pump rotates anti-clockwise.  Westfield recommends that 2.0L Zetec Engine owners replace the single “Vee” the water pump pulley for a multi “Vee” pulley as used on Zetec 1800 Engines. The Auxiliary drive belt is then connected as shown in the photograph, above left. On the Westfield system the crankshaft and water pump rotate in the same direction.  The implication is that the water pump in the Westfield 2.0 Zetec system is running backwards.   Running the pump in reverse will reduce the efficiency of the pump. Operationally this seems to make little difference