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).
Examination and conclusion from tests on water jacket corrosion in various experimental cars.
| Identifier | ExFiles\Box 150\3\ scan0362 | |
| Date | 21th February 1938 | |
| -3- Rm {William Robotham - Chief Engineer} /Std.5/MH. {M. Huckerby} 21.2.38. Examination of the water jackets of 32-EX car at the end of its mileage showed surprisingly little corrosion present, but it must be remembered that this car was fitted with the aluminium hot spot box which is now standard, also that while a steam valve was fitted, a good deal of fresh water had to be added to system due to boiling. Sheet (2) attached, shows the summarised results of corrosion observation on 32-EX, 34-EX, 35-EX and 39-EX cars, while photograph of 32-EX water jackets is also attached. The Laboratory have carried out tests for us to determine whether "No-Co-Ro {C. C. Rose - Export Manager} " attacks rubber hose connections in any way and are of the opinion that it will not affect them appreciably. Attached is a copy of an N.P.L. report on this inhibitor. Conclusions from tests. (1) From the very large difference between the amount of corrosion which has occurred in actual cars water systems and our rig water system with an iron hot spot box fitted in each case, it appears as if either some different set of conditions must occur in an actual engine which might affect corrosion (e.g. local boiling etc.) or else the difference is attributable to continual change of water and consequent aeration of same, due to steam valve not sealing properly and allowing water loss. In this connection it will be seen from Sheet (2) attached, that 34-EX car on its demonstration trip to Nairobi was fitted with an iron hot spot box and no corrosion inhibitor. It was, however, fitted with a carefully checked and set steam valve which effectively sealed the water system. At the end of 2 months running covering 13,000 miles, no water whatever had been lost, and only very slight traces of corrosion of aluminium parts was discernible. The cooling water was as clear as when it was put into the car, while the matrix was entirely free from choking. Further, 32-EX and 39-EX after running for some period with sealed cooling systems, showed negligible amount of corrosion, although in these cases "No-Co-Ro {C. C. Rose - Export Manager} " corrosion inhibitor had been put in the system originally. 35-EX car ran 20,000 miles over a period of approximately 5 months with an aluminium hot spot box and no steam valve fitted, but fitted with four port heads so that the water loss was negligible. The corrosion of the jackets here was in excess of that on 32, 37 and 39-EX but was still only slight. | ||