The water pump, thermostat, and fan are the engine-mounted components of the TD and TF cooling system, appearing within the Engine category because they are physically mounted on the engine and cross-referenced from the Cooling category where the complete system including the radiator, hoses, and coolant is covered. The water pump specification is shared between later TDs and all TFs, but the thermostat and water outlet arrangements differ significantly between the TD and TF, reflecting the change from the TD's non-pressurised cooling system to the TF's pressurised system.
Water Pump
The water pump on the XPAG and XPEG engine is a centrifugal type mounted at the front of the cylinder block, driven by the fan belt from the crankshaft pulley. The pump was modified at engine number XPAG/TD/6482 in February 1951 to incorporate an integral seal, earlier pumps using a separate sealing arrangement, and from that point the specification remained consistent through all later TDs and all TF cars, the XPEG's larger bore not necessitating a water pump change.
The later-type assembly will fit earlier engines, making it the practical choice for any pre-6482 car where the original pump has worn out. A water pump rebuild kit is available, containing the bearings, seal, Woodruff key, and spindle nut, and the pump is mounted to the block using two studs with nuts plus two bolts with spring washers, and a gasket between the pump body and the block.
Thermostat & Water Outlet
The TD thermostat is an integrated thermostat-and-housing unit mounted in the water outlet at the top front of the cylinder head, secured by two studs and nuts with a gasket between the unit and the outlet, and a separate elbow on top carries the top hose connection. The TF uses a fundamentally different arrangement reflecting its pressurised cooling system, a separate Waxstat-type thermostat sitting in a revised water outlet with a plug and sealing washer closing off one of the outlet ports, the top hose elbow being a separate component bolted to the water outlet rather than to the thermostat. TF thermostats are available in three temperature ratings, 74°C for hot climates or summer use, 82°C as the standard rating for normal road use, and 88°C for cold climates or winter use, all three fitting the same TF water outlet and interchangeable within the housing.
Fan & Drive
The cooling fan is a four-blade assembly formed from two pressed-steel stampings bolted together through the water pump pulley with a fan spacer, the TD fan painted black and the TF fan retaining the same construction but painted red, with fan bolts and washers universal and available individually. The crankshaft pulley drives the fan belt and serves as the reference point for ignition timing via the TDC indicator mounted on the timing cover, shared across all XPAG and XPEG engines, and secured by the crankshaft bolt with its integral starting dog, which provides the engagement point for the starting handle that remains the backup starting method on cars of this era. The fan belt is a single specification driving both water pump and dynamo, the same for all TD and TF engines.
When ordering, the essential split is between the TD's integrated thermostat and housing and the TF's separate Waxstat thermostat in its revised water outlet, the water pump itself being universal from engine number 6483 onwards.