From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical bulletin discussing engine overheating caused by choking of the radiator core from hard water deposits.
| Identifier | ExFiles\Box 24\5\ Scan146 | |
| Date | 24th January 1928 | |
| 7766 To Hm.{Capt. W. Hallam - Head Repairs} - for Depots. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG24.1.28. OVER-HEATING. Y766 X8250 Recent tests have indicated that the efficiency of the Rolls-Royce cooling system may be impaired by the choking of the radiator core. At present we believe this choking is due to a slimy deposit in the first two or three rows of the radiator tubes which rapidly collects lime or magnesium sulphate precipitates which form when hard water is boiled. The origin of the slime (which undoubtedly exists) is somewhat obscure, but conceivably a part of it may emanate from the over-lubrication of the water pump gland. The water passages between adjacent tubes are only 1 mm. wide and in consequence it does not require a very large quantity of foreign matter to choke them. [Diagram showing a cross-section of a radiator tube with the label "GAP 1MM"] If the water circulation is sluggish the efficiency of the radiator at once drops and in exceptional cases the pump may become air-locked due to the difficulty it experiences in drawing water through the matrix. Indications of this are the intermittent lighting of the warning lamp even when the shutters are fully open, followed by periods when the car seems to be reasonably well cooled, this indicating that the air lock has been temporarily displaced. If obstruction in the radiator is suspected, the system should be emptied. The top tank contd :- | ||