The standard Westfield installation for the Zetec engine on the SpeedSport 1800 routinely causes an over-cooling problem. This manifests itself by the engine never getting up to temperature on a cold day (often not achieving a temperature greater than 50º) except in a traffic jam. Even in the summer the engine is very slow to warm up and often fails to reach a temperature of over 65º-70º. The problem is exacerbated in the 'ducted fan' nose cone configuration due to the very high efficiency of the radiator. The problem can be partially resolved by the use of a radiator blind as recommended by Westfield but I have had to use two different blinds, one for winter and one for summer and neither allows the engine to operate as it would in a ‘normal’ car - i.e. warm up quickly to 90º and then stay there.
The cause of this problem would seem to be that the thermostat bypass pipe joins the top hose rather than the bottom hose. This results in hot coolant from the engine circulating round the system and through the radiator and, therefore, being cooled rather than being re-introduced into the engine block to assist in the warming up progress. If the engine does reach the ideal running temperature of 90º, the thermostat works as it should and the hot coolant enters the top hose and thence to the radiator. It is getting to the correct temperature in the first place that is the biggest problem.
Various solutions have been suggested to resolve this problem but some are simply too crude:-
1. Closing off the bypass pipe entirely – this causes a back-pressure that causes serious circulation of coolant through the expansion tank that often overflows!
2. Incorporating a ‘T’ piece connection in the small pipe that joins the bottom hose to the heater outlet and connecting the thermostat bypass pipe to this so that hot coolant re-enters the block with return coolant from the heater matrix – this is more elegant than 1. above but the constriction of two 15.8mm pipes into one 15.8mm joining piece causes a similar back-pressure although it does not seem to be quite so extreme.
3. Welding a second 15.8mm pipe into the aluminium part of the bottom hose and connecting the thermostat bypass pipe to this – the advantage of this method is that the relatively high pressure of the15.8mm tube entering the relatively low pressure bottom hose results in no back-pressure problem.
This is a very elegant method of resolving the problem and is probably ideal if you have a 2-litre Zetec engine as the method detailed below will not work with a 2-litre engine as the inlet to the water pump is biased slightly rearwards which would kink the replacement bottom hose too much thus restricting the coolant flow – not good! If you have a 2-litre Zetec engine consider the extra welded outlet method detailed above or you will be pleased to know that a company called Highbury Hose Ltd. (see their details in the 'links' section) can produce a 135º bend bottom hose to suit this application at a very reasonable price of about £23.50 plus postage and packing.
4. Modify part of a Ford Mondeo bottom hose that incorporates various 15.8mm inlets. This is the method that I used and it is ideal for the 1800 Zetec engine and I am indebted to Iain MacCaig (a Sport Carbon owner) who tried the Mondeo bottom hose unit first and then told me about it. However, Highbury Hose Ltd. also now produce a 90º version of the bottom hose and this would be a better route than the one that was open to me when I originally carried out the work as it does not require the 'butchering' of the original Ford part.
Step 1
Purchase either the correct bottom hose from Highbury Hose Ltd. for either an 1800 or 2 litre engine or a Ford Mondeo bottom hose, part number P F1013384 (FINIS number 1013384) for an 1800 engine only from a Ford dealer (£43.25). Naturally, if your engine is a second hand 1800 and it came with it's bottom hose, you can use this. Purchase 1 metre of Quinton Hazell HP478 15.8mm heater hose from Halfords (£2.40) plus 3 off 14-22mm Hose Clips (I had these ‘in stock’). Finally visit a plumber’s merchants and purchase 3 off 15mm straight connectors (the type with the pre-filled soldering ring), 1 off 15mm stop end (the type with the pre-filled soldering ring) and about 6" of 15mm copper pipe.
The unmodified Ford Hose - most gets chopped off!
Step 2
Cut, de-burr and clean to brilliant shine with wire wool, the following lengths of 15mm copper pipe:-
3 off 18mm long
2 off 38mm long
Apply flux sparingly to all mating surfaces, assemble the two units shown below and then using a blow-torch, solder carefully.
Finished copper joining and blanking pieces
Step 3
If you are using the Highbury Hose part skip to Step 4. If you are using the Ford part, cut off the excess pipework from the replacement bottom hose as per the photograph shown below leaving just the ‘elbow’ with the 15mm stub pipe extending out of it’s centre (the cut down hose has been installed in this photograph):-
Modified Ford part installed
Step 4
Drain down the system, remove the existing rubber bottom hose and replace it with the new hose. Insert one end of the joining piece made earlier and secure it with a 14-22mm hose clip. You can see here that I have painted the middle portion of the joining piece black so that when the whole system is installed, the join will hardly be visible.
The long joining piece installed
Step 5
Cut the existing thermostat bypass pipe in half and remove the half connected to the thermostat housing. Fit the stop-ended unit made previously into the end of the remaining half of the bypass pipe and complete the installation with a 14-22mm hose clip to fully seal off this pipe outlet. Again, I have painted it black for appearance reasons.
Short blanking piece installed in feed to top hose
Step 6
Fit one end of the 1 metre 15.8mm HP478 pipe to the thermostat housing with a 14-22mm hose clip. Slide another 14-22mm hose clip onto the pipe in readiness for the final fitting of the other end. Carefully route the other end of the pipe well clear of the exhaust pipes and cut it to a suitable length to mate with the end of the joining piece made earlier. This piece is currently projecting from the 15mm pipe in the middle of the elbow of the new bottom hose. Do not connect it yet – instead, seal up the end with a temporary ‘bung’.
Step 7
Using the remainder of the 15.8mm HP478 pipe as a temporary ‘air bleed pipe’, attach this loosely to the joining piece and start to re-fill the system with the correct coolant mixture. When nearly full, smartly remove the bung and the temporary bleed pipe and connect the free end of the bypass pipe to the joining piece (some coolant will inevitably spill out!).
Secure all the hose clips, complete the filling of the coolant and start the engine. Check for leaks and note with some satisfaction that the engine warms up quicker and maintains a more stable operating temperature.
Bypass pipe attached to modified Ford part
The modified cooling system diagrams below can be compared with the originals in the build manual for reference. Note that the items in red are the modifications and the direction of flow to and from the heater matrix are shown correctly in these diagrams:-
Radiator Connections
Bottom Hose Connections
Top Hose Connections
Heater/Header Tank Connections
On the 30th April 2001, the updated cooling system was given the ultimate test - 120 miles of flat out driving on the Goodwood racing circuit (see diary entry for details). The cooling system operated faultlessly throughout the day proving the integrity of the new system beyond doubt and silencing those who said that it would not be suitable for track use! The coolant temperature rose to 88 º and stayed there solidly. This modification works!
NB. WESTFIELD DO NOT RECOMMEND THIS MODIFICATION!
