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).
The investigation into the cause of top overoiling on the Phantom III engine.
| Identifier | ExFiles\Box 144\3\ scan0114 | |
| Date | 25th September 1936 | |
| To M.{Mr Moon / Mr Moore} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Mx.{John H Maddocks - Chief Proving Officer} Top Overoiling on the Phantom III. We have been going into the question of top overoiling very seriously. We find that all our experimental Phantom III cars give trouble after approximately 3,000 miles. Tests have been carried out on a mock-up rig consisting of a Phantom III crankcase, cylinder head and rockers, the oil supply to the rockers being under pressure, the whole driven by an electric motor, reproducing as near as possible engine conditions. Dealing with the shields on the valve gear, we derive no benefit from fitting these, and some of the oil which drains on to the valve springs passes down the valve stems. Cause of Overoiling. We have proved both on the rig and road that overoiling is caused by the oil passing through the rockers on to the valve tip and down between the wedges, bottom washer and grummet. If we must have this oil supply to the valve tip, then we shall require a more efficient grummet; meanwhile we are running JJ-X with the supply to the valve stems cut off, up to date we have run 1,600 miles without any detrimental results to the valve gear, and the valve tips were well lubricated. The engine, which previous to this modification was overoiling, is now running most satisfactorily. | ||