Kylning Zetec-motor

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Bra och läsvärd information i 5 delar angående kylningen av Zetec-motorn, perfekt för dig som byter från en annan motor i befintlig bil eller bygger eget.

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Part 1 - Introduction to Zetec Cooling Systems

Disclaimer
EM Engineering does not imply or express an opinion that the Zetec Cooling System, as implemented by Westfield Sports Cars is faulty. Any alteration to the Zetec Cooling System, from that implemented by Westfield Sports Cars, is at the owners risk. Westfield Sports Cars and EM Engineering do not accept any responsibility for damaged caused to the engine by implementing any of the example cooling system modifications, in whole or in part.

The opinions expressed, and the engineering practices in this document are those of E.M. Engineering and are not to be interpreted as being attributed to, sponsored by, or supported by Westfield Sports Cars. Parts used in the modification of 1800 and 2.0L Zetec engines, illustrated in this document, are NOT available from Westfield Sports Cars
This paper is published in the full knowledge of Westfield Sports cars subject to the disclaimer above.

Copyright
This document may be copied and distributed for personal use, providing that the distribution is free and the document is reproduced in its entirety, without alteration and with acknowledgement to E.M. Engineering.

Introduction
There is plenty of noise, on the Internet, describing apparent overcooling of Zetec engines fitted to Westfield’s. Most of it is supported by experience of road use and the visual observation of the engine temperature gauge in both winter and summer driving. Verbal reports and e-mail postings describe engine temperatures struggling to reach an operating temperature of 80 °C. Remedies include fitting radiator blinds, used during winter and summer, to re-plumbing the coolant system with a variety of “Tee” pieces to re-route the coolant system similar to Zetec engines used in Mondeo’s.

The purpose of this paper is clarify, the apparent overcooling syndrome, and the variety of remedies implemented by owners, The paper provides information on the cooling system as used on the Ford Mondeo, and as implemented, by Westfield Sports Cars, with Ford approval. EM Engineering has a Westfield SEiW 2.0L Zetec with a modified cooling system and this will be used as an example of owner implemented alterations. The modifications are not track tested and are for road use only.
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Ford Mondeo Zetec Cooling System
1. Radiator
2. Twin Cooling Fans
3. Expansion Tank
4. Filler/pressure Cap
5. Mounting Bolt
6. Single Cooling Fan
7. Mounting Bolt
8. Coolant Pipe
9. Nut
10. Top Mounting Rubber
11. Bottom Mounting Rubber
12. Mounting Bolt
13. Radiator Mounting Bracket
14. Coolant hose
15. Bolt
16. Radiator Top Hose
17. Coolant Pipe / Hose
18. Stud
19. Thermostat Housing
20. Radiator Bottom Hose
21. Expansion tank overflow hose

Diagram, Courtesy of Haynes Publications
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Ford Mondeo Thermostat Bypass Pipe
It is the pipe work of the Ford Mondeo cooling system that is the most interesting to Westfield owners. The first point to note is pipe number 17. This is a metal pipe, of approximately 16mm diameter, which runs between the bottom hose, number 20, in the diagram, and the thermostat housing, numbered 19, in the diagram. This provides a path for coolant circulation prior to the opening of the thermostat. This assists engine and heater warm up.
Secondly the expansion tank, 3, main connection is connected via a relatively large bore hose to the radiator bottom hose, 20. The overflow connection is routed via a rubber hose, 21, and rubber hose, 14, to the top connection on the thermostat housing, 19. The Radiator top hose, 16, is connected to the main outlet of the thermostat housing, 19. The Radiator bottom hose, 20, connects between the Water pump (not shown) and the Radiator, 1.
All Mondeo’s employ a pressurised cooling system with thermostatically controlled coolant circulation. A water pump mounted on the drive belt end of the engine, pumps coolant through the engine. Internal passages pass coolant around each cylinder, the inlet and exhaust ports, near the spark plugs and exhaust valve guides.

A wax pellet type thermostat is located at the transmission end of the engine, in a housing at the top the engine. During warm up the thermostat is closed preventing coolant circulation via the radiator. Instead, coolant is returned from the thermostat housing, thermostat bypass, via a metal pipe across the front of the engine to the radiator bottom hose and the water pump. The supply of coolant to the heater is made from the rear of the thermostat housing. As the engine nears normal temperature, at 88 °C, the thermostat starts to open and allows hot coolant to travel via the radiator, where it is cooled by airflow through the radiator, before returning to the engine via the bottom hose and the water pump. As the thermostat opens to allow coolant to flow through the radiator it correspondingly closes the port to the bypass cutting off the flow through the bypass.

A pressure type filler cap, in the expansion tank, seals the cooling system. Operating at about 1.2 bars, the pressure in the system raises the boiling point of the coolant and increases the cooling efficiency of the radiator. When the engine is at normal operating temperature the coolant expands and the surplus is displaced into the expansion tank. When the system cools the surplus coolant is automatically drawn back from the tank in to the radiator.
Under high temperature conditions, such as slow or stationary traffic in hot weather, cooling airflow is maintained through the radiator by a cooling fan. The cooling fan is operated by the ECU receiving coolant temperature information from a sensor in the thermostat housing. The fan may be either single or two speeds.Fan Operating Temperatures °CONOFF
Single Speed or 2 speed fans – 1st Stage100
2 Speed – 2nd Stage103
Single Speed or 2 speed fans – 1st Stage93
2 Speed – 2nd Stage100
Table 1 Mondeo Fan Switch Operating Temperatures
The Westfield Cooling System
Ford approves the Westfield cooling system. Any alterations undertaken by the owner may invalidate the warranty. The Westfield Zetec Cooling installation is characterised by the connection of the thermostat bypass via a rubber hose, to the main pipe joining the thermostat outlet and the radiator top hose. This provides coolant via the radiator regardless of the position of the thermostat. The Westfield system is complicated by the detail changes of, ducted and non-ducted nose installations. The following schematic diagrams show how the system is connected.

Non-Ducted Nose
The schematic diagrams below are largely, self-explanatory.
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Diagram , Courtesy of Westfield Sports Cars

Non-Ducted Nose, Diagram 7,
Shows the connections to the radiator bottom hose and the heater connections.
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Diagram , Courtesy of Westfield Sports Cars

Non-Ducted Nose, Diagram 8,
Shows the radiator top hose connections to the thermostat housing. The thermostatic switch for the fan is located in the pipe, adjacent to the thermostat housing.
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Diagram , Courtesy of Westfield Sports Cars
Diagram 48 Non Ducted Nose – Shows the connection of the heater and expansion tank connections. The arrows showing the direction of flow in and out of the heater are incorrect. Hose “P” is the inlet to the heater and Hose “N” is the outlet.
The Westfield expansion tank is considerably smaller than the one fitted to the Mondeo.
Non-Ducted Nose Operational theory
In the non-ducted nose cooling system the coolant pump circulates coolant through the standard internal passages in the Zetec engine block. With the thermostat closed coolant continues to flow via the thermostat bypass, the radiator top hose, to the radiator, where it is cooled by airflow through the radiator. Coolant returns via the bottom hose and the water pump to the engine. On reaching operating temperature the thermostat opens and provides the main flow of coolant to the radiator, increasing the volume of coolant and superseding that being provided via the thermostat bypass. In low air flow conditions, such as heavy slow moving, or stationary traffic, additional cooling air is provided by a thermostatically controlled fan. The fan switch is mounted in the alloy pipe connecting the thermostat housing to the radiator top hose, adjacent to the thermostat outlet. The fan switch sensor samples coolant temperature. Two types of switch are provided “Red Top”, Ford FINIS No: 7001614 (88 - 77 °C) used on engines fitted with Carburettors and “Orange Top”, Ford FINIS No: 7001611 (106 – 92 °C) used in Fuel injected cars with a catalytic converter. In high temperature conditions the fan switches on providing additional cooling air through the radiator until the coolant temperature falls below the switch off point.
Ducted Nose

There are detail differences between non-ducted and ducted nose installations. The non-ducted nose can be removed leaving the radiator and associated cooling pipe in place. In the ducted nose installation the radiator, cooling fan and associated ducting are mounted on the nose cone. Removal of he nose cone necessitates draining the cooling system.
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Diagram 51 Courtesy of Westfield Sports Cars

Like the non-ducted nose, the thermostat bypass is connected to the radiator top hose. However the radiator cooling fan switch is repositioned in to the radiator. Additional pipe work is provided to connect the expansion tank overflow to the radiator top hose. See diagram above.
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Diagram 52 Courtesy of Westfield Sports Cars

The diagram above shows the ducted nose radiator top hose connections. Note the small bore pipe provided to connect the expansion tank overflow to the radiator. This feature was not incorporated in to the non-ducted nose.
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Diagram 53 Courtesy of Westfield Sports Cars
Ducted Nose Diagram 53, (left) completes the picture, showing expansion tank and heater connections. In the ducted nose, the header / expansion tank overflow is connected to a “tee” piece and then to the thermostat housing and the radiator top hose.
The Westfield expansion tank is considerably smaller than the one fitted to the Mondeo.
Ducted Nose Operational Theory
Since there are only detail differences between them, the theory of operation should be the same as the non-ducted nose. Greater cooling is achieved by ducting hot air out from the radiator to the exterior of the car, rather than exhausting it in to the engine bay as with the non-ducted nose installation.

Operational Performance
The Standard installation for the Zetec engine is routinely the subject of reports of low operating temperatures from both non-ducted and ducted nose installations. This manifests itself in reports of the engine never getting to operating temperature on a cold day (often not achieving a temperature greater than 50˚C) except in a traffic jam. Even in summer the reports continue with, “The engine is slow to warm-up and often fails to reach 65 – 70 ˚C”. The cause would seem to be that by connecting the thermostat bypass to the radiator top hose, the Westfield system is too efficient. The Most common remedy amongst customers, to reduce the efficiency of the system, and increase operating temperatures is with some form of radiator blank or blind, to restrict the cooling air passing through the radiator. Many Westfield customers find that to achieve anything like normal operating temperatures of 80+ °C the blind must be used winter and summer. The implication of this is that, in normal use, the thermostat rarely opens and the majority of the cooling is taking place via the thermostat bypass pipe.
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Chart, Courtesy of Steve Richards
The situation is illustrated by the graph (left) of an 1800 Speed Sport, ducted nose car. The graph shows, temperature / time of a test, conducted on a customers, stationary, vehicle in still air, and an ambient air temperature of 16 ˚C. It took 6 minutes for the temperature gauge to register a minimum 40 °C, 17 minutes to reach 88°C and 24 minutes for the fan to come on. Following on with a 5-mile drive the temperature settled to a stable 70 °C. The blue line shows temperature indicated by the VDO temperature gauge and the Red line temperatures as reported by a Laptop PC. There is a considerable discrepancy between the temperatures recorded on the gauge and the Laptop. Subsequent tests have shown that the gauge is accurate
Whilst radiator blinds may have been acceptable in the 1950’s, they are not acceptable on a modern day sports car, doing little to enhance its image. This is why customers have adopted alternative solutions. Most of these are modelled on the Ford Mondeo cooling system and involves re-routing the thermostat bypass

Increasing the Operating Temperature
The task is to increase the operating temperature, by reducing the cooling efficiency of the Westfield, using a standard, well engineered, solution. Using the Ford Mondeo as a standard, the most significant difference is the routing of the thermostat bypass. The Westfield cooling system installation connects the thermostat bypass to the radiator top hose; the Ford Mondeo connects the thermostat bypass to the bottom hose. The Westfield system increases cooling efficiency, by sending a supply of coolant via the radiator irrespective of the thermostat position. With the thermostat closed the thermostat bypass simply acts as a restrictor in the flow of coolant to the radiator. In worst case, low ambient temperature, it is possible that sufficient coolant will flow via the bypass and the radiator, that the engine will never reach thermostat-opening temperature. By contrast the Ford Mondeo system splits the coolant circuit in to primary and main coolant circuits The primary circuit, via the thermostat bypass to the bottom hose, assists warm up and coolant circulation until the thermostat opens. Once the thermostat opens, coolant flows via the radiator. Opening the thermostat correspondingly closes the thermostat bypass. The engine temperature is then controlled by the thermostat via the radiator. Emulating the Mondeo would reduce the efficiency of the Westfield system and provide a solution stop the overcooling syndrome. However increasing the operating temperature will cause increased coolant expansion. The smaller size of the Westfield expansion tank is a potential problem.

There are other minor differences between the Westfield and Mondeo installations but these will have little effect on the overall operation of the engine. The Westfield shares the heater feed with the expansion tank. These are separate in the Mondeo. The Westfield build manual (certainly for the 1800Q) wrongly indicates heater inlet and outlet. The heater inlet is fed from the back of the thermostat housing and the outlet is shared with the expansion tank. This is probably a drawing error with no operational effect.

The Mondeo and the non-ducted nose installation connect the expansion tank overflow to the top of the thermostat housing. The ducted nose installation also connects the overflow via a “Tee “ piece to the top hose of the radiator. This would have a beneficial effect on hot coolant expansion in to the tank by providing a bleed path via the radiator thus and reducing coolant expansion.

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Del 2
Part 2 - Modifying the Westfield Cooling System
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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.
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.
2.jpg
Zetec 2.0L Water Pump Inlet
3.jpg
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.
Ford Zetec 2.0 litre, ducted and non-ducted nose, using a modified Alloy pipe.

Ford 1800 Zetec, ducted and non-ducted nose, using a modified Mondeo Pipe.
Zetec Water Pumps
4.jpg
Westfield Auxilliary Drive Belt
5.gif
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
6.jpg
The diagram left, shows a typical water pump and explains why the pump will work in either direction. The inlet is to the centre of the impeller and the blades push the coolant to the outlet, regardless of rotation. Impeller design means it will be more efficient when rotated in the correct direction.

Owners may feel that in any event they would like to correct this situation. The Zetec water pump is replaceable as a complete unit. The solution is to replace the 2.0 Zetec water pump with an 1800 Zetec water pump.

Zetec owners who replace the 2.0 Zetec water pump with an 1800 Zetec water pump can use the modified Mondeo bottom hose solution.

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Del 3
Part 3 - Modifying the Westfield Ford Zetec 2.0 Litre Cooling System
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The schematic diagram shows a new junction welded in to the alloy pipe running between the radiator bottom hose and the water pump inlet. This junction is connected via a new alloy pipe to thermostat housing bypass outlet. The new junctions and pipe work have anti blow off ends formed by running a weld around the circumference of the pipe.

The heater connections are not modified
Radiator bottom hose connections (Modified)
2.jpg
3.jpg
The diagram, above left, shows the modified alloy pipe. It is not to scale and is dimensionless to allow the modification of the pipe to suit the vehicle. On our car there was sufficient room to weld a second junction to the pipe, leaving suitable clearances to fit the rubber hoses. Anti blow off ridges were formed by welding around the circumference of the pipe .

The photograph, above right, shows the modified bottom hose alloy pipe on situ,. The right hand junction is connected the heater and the left hand junction is connected to the new bypass pipe.
4.jpg
5.jpg
A suitable bypass pipe can be manufactured to the approximate dimensions as above. Made from 16mm alloy or copper tube with a bend formed at each end. The downward end, which connects to the modified alloy bottom pipe is formed at 15˚ from the vertical or 75˚ with respect to the horizontal junction, which connects to the thermostat housing. Anti blow off ridges can be made by running a weld round the circumference of the pipe. If copper pipe is used suitable bends can be made from “Yorkshire” solder fittings.

The photograph shows the new bypass pipe connected to the modified bottom hose alloy pipe and routed alongside the heater pipe. The bypass pipe and heater pipe are secured together, at regular intervals, using pipe / wiring clips available from Vehicle Wiring Products.
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7.jpg
The Diagram (above) shows the Radiator top hose connections modified. An alloy pipe, “J”, from the radiator top hose to the main thermostat-housing outlet this pipe has the junction that was connected to the thermostat bypass. This must be blanked off and sealed. This pipe also contains the thermostatic switch for the fan. If you have a “red top” switch Ford FINIS No: 7001614, replace it with an “orange top” switch Ford Finis No: 7001611.

The photograph above right shows the connections to the Thermostat housing. The thermostatic switch (blue plug) can be seen, fitted in to the pipe from the main thermostat-housing outlet. Beneath this pipe is the rubber hose connecting the new bypass pipe to the thermostat bypass outlet. The blanked off connection in the main pipe was made using a ½” BSP adapter and an M10 Bolt. The pipe was tapped to ¼ ”BSP thread and the adapter was, internally, tapped to match the M10 bolt. The ¼ ” BSP adapter was wrapped in PTFE tape to seal it and screwed in to the pipe. The M10 Bolt was similarly wrapped in PTFE tape and screwed in to the adapter. This arrangement has proved watertight
8.jpg
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The Photograph (above left) shows the coolant pipe running down the Left had side of the body. The alloy pipes are fastened together using pipe clips to provide a neat and secure installation.

Diagram 48 (above right) shows that the heater connections are unmodified. However due to the substantially smaller Westfield expansion tank, to ensure that there is sufficient expansion space in the header tank, the system should be filled to half way between the minimum and maximum marks on the tank

Ford 2.0 L Zetec Ducted Nose, Modifications
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The modification of the ducted nose is the same as non-ducted nose. Just the layout detail is different, caused by the radiator being fixed to the nose cone and not the chassis. The diagram (above left) shows the bottom hose connections with a new junction welded to the alloy pipe as before and connected to the water pump inlet. A rubber hose connects to the new junction to the alloy bypass pipe. Which is connected at the opposite end, to the thermostat housing bypass outlet.

Similar to the non ducted nose installation the alloy pipe connecting the Radiator top hose and the main thermostat housing outlet has the redundant junction, formerly used for connecting to the thermostat bypass (above right). This must be blanked off and sealed
The Thermostatic switch for the fan is mounted in the radiator. If you have a “red top” switch Ford FINIS No: 7001614, replace it with an “orange top” switch Ford Finis No: 7001611 for normal fan operation.
12.gif
The heater connections are unmodified.
The diagram (left) shows again the new thermostat bypass pipe and the blanked off junction in the pipe to the radiator top hose.

Because of the smaller size of the Westfield expansion tank. To ensure that there is sufficient expansion space in the header tank, the system should be filled to half way between the minimum and maximum marks on the tank.

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Del 4
Part 4 - Modifying the Westfield Ford Zetec 1800 Cooling System
1.jpg
The water pump inlet on Ford Zetec 1800 is at right angles to the cylinder block. This facilitates an easier solution of the bottom hose connection, to the thermostat bypass pipe. Using the bottom hose connection from a Ford Mondeo. (Ford FINIS No: 1013384) (Left)
The modification involves cutting the Mondeo hose almost in half, just in front of the reinforced section with the multiple branches. This end would normally be connected to the Mondeo radiator can be discarded. The remainder provides an angled pipe with a single branch that can be used to connect to the thermostat bypass.
A separate bypass pipe is still required and can be made from ½” hose connected to the thermostat bypass outlet and clipped securely to the existing coolant pipes. In line pipe connectors of plastic or alloy can be used to join the bypass pipe to the Mondeo hose. Care must be taken with this installation to ensure coolant flow is not restricted by hosepipes that are kinked or distorted.

Ford Zetec 1800 Non-Ducted Nose Modifications
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Radiator bottom hose connections (Modified)
3.jpg
1800 Sport Carbon showing modified hose
The schematic diagram (above left) shows a modified Mondeo bottom hose connected to the alloy pipe running to the radiator bottom hose. This junction is connected via a new alloy pipe to thermostat housing bypass outlet. The new bypass pipe has anti blow off ends formed by running a weld around the circumference of the pipe
½” Rubber hose could also be used as a thermostat bypass. Care should be taken to avoid sharp kinks and bends, which would collapse the hose and restrict coolant flow. The rubber hose bypass pipe should be firmly secured, away from the exhaust system. Take care not to crush the pipe at the securing points
The Photograph (right) shows a Westfield Sport Carbon 1800 cooling system using a modified Mondeo bottom hose, and a rubber bypass hose
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5.jpg
Diagram (above left) shows the Radiator top hose connections modified. An alloy pipe, “J”, from the radiator top hose to the main thermostat-housing outlet this pipe has the junction that was connected to the thermostat bypass. This must be blanked off and sealed. This pipe also contains the thermostatic switch for the fan. If you have a “red top” switch Ford FINIS No: 7001614, replace it with an “orange top” switch Ford Finis No: 7001611

The photograph above right shows the connections to the Thermostat housing. The thermostatic switch (blue plug) can be seen, fitted in to the pipe from the main thermostat-housing outlet. Beneath this pipe is the rubber hose connecting the new bypass pipe to the thermostat bypass outlet. The blanked off connection in the main pipe was made using a ½” BSP adapter and an M10 Bolt. The pipe was tapped to ¼ ”BSP thread and the adapter was, internally, tapped to match the M10 bolt. The ¼ ” BSP adapter was wrapped in PTFE tape to seal it and screwed in to the pipe. The M10 Bolt was similarly wrapped in PTFE tape and screwed in to the adapter. This arrangement has proved watertight
Diagram 48 (right) heater connections are unmodified.
Because of the smaller size of the Westfield expansion tank. To ensure that there is sufficient expansion space in the header tank, the system should be filled to half way between the minimum and maximum marks on the tank
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Ford Zetec 1800 Ducted Nose, Modifications
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The modification of the ducted nose is the same as non-ducted nose. Just the layout detail is different, caused by the radiator being fixed to the nose cone and not the chassis. The diagram (above left) shows the bottom hose connections with a new junction welded to the alloy pipe as before and connected to the water pump inlet. A rubber hose connects to the new junction to the alloy bypass pipe. Which is connected at the opposite end, to the thermostat housing bypass outlet
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1800 Speed Sport, Ducted Nose cooling system modified using a Mondeo bottom hose.
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In line pipe connector manufactured from plumbers solder fittings
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Bypass hose connected
Similar to the non ducted nose installation the alloy pipe connecting the Radiator top hose and the main thermostat housing outlet has the redundant junction, formerly used for connecting to the thermostat bypass (above right). This must be blanked off and sealed.

The Thermostatic switch for the fan is mounted in the radiator. If you have a “red top” switch Ford FINIS No: 7001614, replace it with an “orange top” switch Ford Finis No: 7001611 for normal fan operation.
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In line connector and blanking cap made from 15mm plumbing fittings
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Blanking cap fitted to ½” hose to seal the redundant bypass connection.
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The heater connections are unmodified.

The diagram (left) shows again the new thermostat bypass pipe and the blanked off junction in the pipe to the radiator top hose.

Because of the smaller size of the Westfield expansion tank. To ensure that there is sufficient expansion space in the header tank, the system should be filled to half way between the minimum and maximum marks on the tank

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Del 5
Part 5 - Testing “The Overcooling Syndrome Overcome”

Following the modification of the cooling system, extensive tests were carried out using our Zetec 2.0 Litre. We also had the benefit of access to data from testing carried out on an 1800 Sport Carbon and an 1800 Speed Sport, with unmodified and modified cooling systems.

Road Tests
Our Westfield cooling system was modified during the build, so no data was available for the unmodified system. During 2000 miles of motoring over the summer and autumn of 2000, no problems with overheating or overcooling were observed. In open road conditions the indicated temperature was a constant 90ºC.. In low speed, low airflow conditions the indicated temperature reached 100ºC. at which point the fan operated and cooled the temperature down to 95ºC. at fan switch off. Owners driving the 1800 Speed Sport and the 1800 Sport Carbon report similar temperatures and operation to our car.

Static Tests
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Chart 5 Westfield Speed Sport 1800 Zetec Unmodified

Average Difference in Temperature 15.8 ºC, Cooling Fan came on after 24 minutes, After the test a 5 mile drive in open road conditions the VDO Gauge stabilised at 70ºC
Having observed the performance on the road we needed to verify the accuracy of our observations. Tests on an unmodified Speed Sport showed differences in the VDO gauge readings and the temperatures reported by the Laptop PC, connected to the ECU, averaging 16ºC. (See Chart 5). These differences needed to be understood and the true result determined. Was the VDO gauge or Laptop accurate? VDO stated that the accuracy of the gauge was 2.5% FSD (full scale deflection) or +/- 3ºC. The average discrepancy reported by the Lap Top software gave cause for concern. The laptop reading originated from the Ford Sensor mounted in the thermostat housing via the ECU. Our car had a Ford Mondeo Sensor mounted in the identical place but unused, because our car has carburettors fitted. We decided to use the Ford sensor to check the accuracy of the gauge and laptop display
Testing our Zetec 2.0 Litre
The first task was to determine the temperature / resistance characteristics of the VDO and Ford Temperature Sensors. Using data we obtained from VDO, Ford, Haynes Publications and some mathematical analysis, we were able to deduce the thermal coefficients and plot the Resistance / Temperature characteristics of the sensors fitted to our car. (Refer to Chart 1 & 2)
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Chart 1 Ford Temperature Sensor Thermal Response
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Chart 2 VDO Temperature Sensor Thermal Response
Test 1
We emulated the test on the 1800 Speed Sport. The vehicle was set up on axle stands in the garage and in still air. Ambient temperature was 2ºC. The engine was run at idle speed observing Ford Sensor resistance and VDO Temperature Gauge Readings at 1-minute intervals. The object of the test was to compare the results with those from the Speed Sport and to verify the data we had calculated for sensors. (Refer to chart 6).
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Chart 6 Westfield 2.0 Zetec Modified cooling System Test 1
The results were as predicted by the resistance / temperature data for the Ford Sensor and the VDO Gauge readings experienced during road testing. There was a close correlation between temperatures reported by the Ford Sensor and the VDO Gauge readings.
The thermostat can be seen to open, after 14 minutes, with a corresponding reduction in temperature as coolant flowed through the radiator. The engine continued to warm up to 100ºC where the Fan was observed to come on.
FANTimeVDO
Temp
Ford
Temp
On20:24100101.09
Off21:189893.30
On22:34100100.95
Off23:269893.83
Comparison of our test, with the test on the Speed Sport 1800 (Chart 7) shows similar readings for both VDO Gauges. The Ford sensor broadly agrees with the VDO Gauges, The laptop appears to be over reading by a significant amount and is therefore suspect. The modified cooling system on our 2.0 Zetec lags behind the Speed Sport, at first, but this is explained by the fact that the test were done at ambient temperatures of 2ºC and 16ºC respectively. After 10 minutes both vehicles have reached the same temperature. Subsequently the modified cooling system of 2.0 litre Zetec is always ahead and hotter than the Speed Sport. The 2.0 litre thermostat opens at 14 minutes and 3 minutes later on the Speed Sport. The cooling effect of the thermostat opening is much more pronounced on the 2.0l Zetec engine than the unmodified Speed Sport. By the end of the test, the 2.0 Litre Zetec had gone through 2 cycles of the cooling fan, to one of the Speed Sport.
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Test 2
Following on from Test 1 it looked more likely that the VDO gauge was accurate. To prove VDO gauge accuracy we attempted to measure VDO sensor resistance / time as the engine warmed up as we had done for the Ford Sensor. However the results were inconclusive for two reasons. The resistance of the VDO sensor is much less than the Ford Sensor.

The resistance readings were measured using a digital multimeter. The low value of the sensor resistance (287 ohms at 40ºC) combined with the multimeter voltage caused some internal heating of the sensor and a corresponding error.(There is dissipation power, D mW/ºC, quoted for all thermistors. This is the power that must not be exceeded if the self-heating error is to be prevented)

The low value of resistance meant that over the temperature range 80ºC to 100ºC the readings were very volatile and difficult to determine accurately.
We designed a test circuit to overcome these problems. The circuit used very low voltages across the sensors, to keep the thermistor power below the critical value, and then scaled these voltages to a value between approximately 5 volts and zero volts over the range 40ºC to 120ºC for both VDO and Ford Sensors. The accuracy of this circuit was to within 0.5ºC. Calibration tests showed that operational and design performances were almost identical (See Charts 3 and 4).
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7.jpg
During the design stage we produced a look up table, to convert voltage to temperature, at 0.5 ºC. intervals over the operating range of the VDO gauge. This table was dynamic, in that we could enter calibration data from the test to compensate for ambient temperature and the climatic conditions of the day.The results from the test were interpolated using the look up table and further interpolated between adjacent cells to obtain accuracies of less than 0.5 ºC.

For the test, the engine had been pre–warmed to just below 40 ºC. whilst the test box was calibrated. Using a digital multimeter for each channel we took readings at 1-minute intervals as the engine warmed up. We concluded the test after three cycles of the cooling fan. (Refer to Table 1)
Ford 2.0L Zetec Engine Cooling System Test data

Sunday 11th Feb 2001

Ambient Temperature 11.5 ºC.
On the day of the test the ambient temperature was 11.5ºC.The engine warmed up normally. The Engine Temperature decreased between 4.5 and 5.5 minutes, 87ºC., as the thermostat opened. Once the thermostat was fully open the temperature rose steadily until the fan came on after 14 minutes 36 seconds, 98ºC.This was a slightly lower temperature than anticipated. The fan remained on for just over a minute, by which time the engine had cooled to 92.5ºC. Further cycles of the fan produced consistent on and off temperatures, more in line with expectation.This can be seen from the oscillations of the graph between 15 and 25 minutes.
TimeFord [V]VDO [V]Ford [ºC]VDO [ºC]Fan operating times & temperatures
04.895.3943.542.6TimeFord [ºC]VDO [ºC]Fan
14.344.752.853.414:3698.998.4ON
23.543.8166.367.215:4892.992.4OFF
32.72.7678.781.318:50101.7101.5ON
42.092.3287.387.020:1795.692.4OFF
52.122.4286.985.723:20103.0101.5ON
62.322.3584.186.624:4096.192.8OFF
72.272.484.885.9
82.082.387.487.2
91.842.0990.889.9
101.7921.98991.591.2
111.7131.89292.692.5
121.6011.74394.294.4
131.4831.6795.895.4
141.3471.43497.798.4
151.3781.36297.399.4
161.756292.591.3
171.6461.76793.594.1
181.2541.55999.096.8
191.0381.218102.4101.5
201.3911.68597.195.2
211.5221.8895.392.6
221.271.6198.896.1
231.061.39102.099.0
241.181.46100.198.1
251.561.9694.791.6
Table 1. Test 2 Results
There is a high degree of correlation between the temperatures recorded by the two sensors. (Refer to Chart 8). The discrepancies after 22 minutes are caused by the fact that we only recorded voltages to 2 decimal places and not 3 as previously. At worst case this data degradation could produce temperature differences of between 2 and 4 degrees between the two sensors.
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Chart 8 2.0L Zetec Ford / VDO Sensor Test
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Chart 9 Engine Temperature Comparison between Modified and Unmodified Cooling Systems
Chart 9 concluded our tests by comparing our results with the data we received from the unmodified Speed Sport and the modified Sport Carbon and Speed Sport. For consistency we chose to compare temperatures recorded by the VDO Gauge. In all cases the modified cooling system engines warmed up faster than the unmodified Speed Sport. The Thermostat opening can be seen to occur earlier and with a more marked cooling effect than the unmodified cooling system. The 2.0 Zetec engine appears to reach fan switch on temperature faster than the 1800 Engines. Different ambient air temperatures, the different methods of modification, (Alloy pipe / Mondeo bottom hose) could cause the differences. Other factors could be the efficiency of the radiators or the differences between ducted and non-ducted nose. Overall the modified engines performed in a similar manner with no signs of overheating or overcooling.

Conclusions
The Westfield cooling system can be modified using a separate bypass pipe to increase engine temperature. Some expansion will take place in to the header tank but this is normal and should not overflow providing the cooling system is not overfilled. Because of the reduced size of the Westfield expansion tank compared to that fitted to the Ford Mondeo, as a precaution, we would recommend filling and maintaining the system coolant level to half way between the min and max marks in the header tank.
The 2.0 L Zetec Engine behaved exactly as predicted and as observed in test and road conditions. The temperatures observed on the VDO temperature gauge fitted to the car are corroborated by the test data produced and are a reliable guide to engine temperature.
Zetec 1800 engines can be modified using a modified Mondeo bottom hose, (Ford FINIS 1013384).
The modified cooling systems of 1800 Zetec engines performed in a similar manner to the 2.0L Zetec engine. Operating at 90ºC in free airflow conditions warming to 100ºC in still or low airflow conditions. The fan operated at 100ºC and cooled the engine down to 95ºC at switch off. These temperatures are consistent with published data for the Ford Mondeo
Engines fitted with Ford “Red Top (Ford FINIS 7001614) thermostatic switch need to be replaced with Ford “Orange Top” (Ford FINIS 7001611) switch to achieve normal fan operation.

Acknowledgements
E.M Engineering acknowledges the assistance given by: -
Westfield Sports Cars Ltd, VDO – Keinzle Ltd, Haynes Publishing, Ford Motor Company, Steve Richards – Oakwood Data Ltd,Andrew Mumford – E.M. Engineering, Tim Hoverd.

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