Section XVI The Cooling System and Fan

Warning:- Before carrying out any modifications to the standard design seek written approval from the Kit Designer. Use only high quality materials and fasteners and lock all threads. This applies particularly to Safety Critical items such as Brakes, Steering & Suspension Components.

At first glance there does not seem to be anywhere to put the Coolman Radiator, let alone an Electric Fan. As you can see from the photo it slips down at a steep angle into the first " bay " on the chassis. It can just be wangled in without any cutting and more or less wedges itself in place. This is of course most unsatisfactory and it needs to be mounted in a more positive way. Cut away the radiator side frames where they touch the chassis to give about 1/8" clearance and mount the top and bottom of the radiator on 4 suitable brackets with rubber bobbins (as on the original car) to isolate the radiator from any chassis movement. If you do not 100% isolate the radiator in this way it will soon leak, when the chassis distorts, so will the joints in the radiator, which will soon crack. The radiator sits at a steep angle but this is unavoidable. The Electric Fan unit from a Citroen BX is recommended and this has been mounted in front of the front cross member with the Citroen rubber bushes fitted into the top of the lower cross member and the top sides attached to the upper cross member with two rubber bobbins and simple brackets pop riveted in place. See photo. The original single top mounting bracket has been cut off as it is no longer required.

The bottom hose outlet fouls the chassis cross member and this will need cutting away to clear the outlet hose and clip. (later models of the 2B have had this error corrected as the front cross member has been tilted up, this also cures the steering rack "wedge" problem) Hot water from the cylinder head goes in at the top of the radiator, and the heavy cold water comes out at the bottom. The small take off manifold on the pump goes to the heater output. ie:- The pump is drawing cooled water out of the heater, hot water is forced into the heater via the cylinder head and inlet manifold, returning back to the pump. The small outlet on the thermostat housing can be blanked off or used as a air bleed. No hoses are supplied in the kit, so it is down to the builder to source suitable hoses that will connect to the various parts of the system. The top hose c/w fabricated thermostat housing was cut up from a Quinton Hazell RH 1260 and a Motorcraft 88BB 8286 D see photographs. The bottom hose was more of a problem and a number of solutions were tried before coming up with the hose assembly shown in the photographs. Working on the assumption that finding one hose to do the complete job would be impossible, the ultimate solution is a composite hose made up of 5 parts. The hose that fits onto the water pump is a Motorcraft 05248 87BB 8260 BA with the lower portion cut off where it goes vertical. The Quinton Hazell RH 1061 is cut into 3 pieces, the 45 degs bit goes on the radiator outlet, and the 90 degs bend joins directly to the sawn off lower end of the Motorcraft pipe. These 3 pieces of hose are joined together with 50mm and 180mm pieces of 32mm o/d stainless steel tube and no less than 6 hose clips. Plenty of scope for leaks here. This does however give a very elegant solution to a tricky problem, probably as good as you will get. If anyone has a better solution please let me know. There are other hose part numbers on the RHOCaR site but I have been unable to locate any of these. The photographs give a good idea of the end result. Ford main agents are no longer able to supply hoses for older cars.

The Polo heater was connected up using hoses from the donor and a length of domestic copper tube. The o/d of the ends was increased using a couple of pipe joiners which also act as a ribbed grip for the hoses.

Clean up any castings on the pump etc, use new hose clips and lightly smear all the flanges with jointing compound. If you intend to stay with the Ford Sierra Heater (or any other water filled heater) and the Ford inlet manifold, then the water circuit will be identical to the original car, only the routing alters. Note that the lower water pump bolt is a "special" to accept the plastic insert on the Cambelt cover. The full system includes Radiator, Inlet manifold heater, Heater and Demister, Thermostat and Water Pump, if you are fitting the Citroen BX Fan then a thermostat, and possibly a relay, will need to be inserted into the top hose. These items can be purchased from Stafford Vehicle Components Ltd. Fan Belt is a Bosch AVX 10 x 90

When fitting the engine thermostat ensure that the wax capsule and spring locates into the engine side. If you are buying a new thermostat, then use Motorcraft Part No. ERT 122 X1 1 635 905. Before fitting give it a quick test in a pan of water "on the boil". It will NOT OPEN in boiled water poured out of a kettle. It must be a "rolling boil" as they say in the cookery books.

One item that does seem to have been missed is a radiator header tank. This is so arranged that any output from the radiator overflow pipe passes into a small tank, usually a plastic bottle. When the radiator cools this overflow water is sucked back into the radiator ensuring that the system is 100% full at all times. If possible arrange the header tank higher than the rest of the system. Correctly positioned this tank will compensate for minor leaks in the system, as any air finds its way upwards, and the actual radiator cap need never be removed. The top seal of the radiator cap will need a rubber gasket. This is exactly the same as virtually all modern production cars. You may even be able to use the Sierra unit, do not pressurize the bottle.

Before you leave this part of the car make sure the Nosecone fits without any interference. Once the Nosecone is finally fitted you will need to blank off the gap between the Radiator and the inner walls of the Nosecone to ensure that ALL the air entering through the front grille must pass through the radiator matrix and not round the sides. Air will take the easy path and you need to pressurize the inside of the Nosecone chamber and force the air through the matrix. Electric fans are a mixed blessing as when not actually in use they cause an obstruction to the incoming air. Some form of thermo-electric cut-out will be required to turn the fan on/off dependent on water temperature. It might be a good idea to put a micro switch on the nosecone to isolate the fan when the nose is hinged up.

There is an excellent solution to this and other fan related problems on the RHOCaR Web Site This circuit electrically isolates the fan during starting, giving full battery power when you need it most. Once the engine fires the fan is reconnected. The thermostat in this circuit is an ordinary domestic central heating unit, which of course is adjustable. When buying one make sure it has 3 contacts, input, normally open and normally closed. This is slightly unusual as most units only have 2 contacts. Input and normally closed. Wire up to the normally open contact (fan off) when the engine temperature rises, this contact closes and the fan is turned on via a suitable 35amp relay. I used a Prodigy Italiana TR(TW)711/N II thermostat made in Milan, Italy. You can also find a circuit diagram in the AutoCAD section.

A third solution is to wire the fan relay to the R terminal (yellow) on the ignition switch. (note that this supply is NOT fused, so you will need to fit two fuses to protect the relay and fan circuits) Note that the Purple wire in the PWS loom is live, even during cranking. The R terminal is only live when the Ignition ON but goes dead on cranking the starter motor. This means that the fan is always (potentially) live but dead during starting, only going into RUN mode when the thermostat switches the relay via pins 85 & 86. This is more or less as the RHOCaR circuit but the relay earth goes to the chassis not the starter solenoid. The fan supply is via relay pins 30 & 87. Use a heavy duty relay (35 amps) and a 35amp fuse, also cable suited to a heavy current and a long cable run. (use similar wire to the existing flying leads on the fan, 28/.030)

For more information on Cooling Systems go to www.centuryperformance.com on the Links page.

Tip. If your engine is temporarily overheating turn the heater on full blast as it acts as an additional radiator. (the cause of the overheating should be investigated ASAP)

The attached photographs show a typical installation and hose layout with some details of the Thermostat Capillary manifold and mounting details of the body.

Detail of housing	Top hose	Thermostat mtg.	Top hose detail
	More Top Hose detail	Bottom Hose detail

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© Colin Usher 2005