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).
Summary of the factors that influence engine overoiling and methods to reduce it.
| Identifier | ExFiles\Box 178\1\ img148 | |
| Date | 19th May 1926 | |
| - 16 - SUMMARY OF FACTORS INFLUENCING OVEROILING. 1. Overoiling is usually evident by:- Excessive Oil Consumption and/or Smoky Exhaust when running light. 2. The chief factors are:- (a) Rate of Oil Flow through Bearings. (b) Piston Rings. 3. Factor (a) is the more important of the two as the latter - even "L" section rings - will not effect a permanent cure if the oil flow is excessive. 4. Piston rings are important in order to obtain maximum economy, when the oil flow is at a minimum. 5. Oil leakage can be reduced in two chief ways - (a) Reduced bearing clearances. (b) Reduced pressure. The former is the more reliable method and apart from other reasons it must be remembered that a pressure of 25 lbs/sq." is required for the efficient operation of the ignition oil relay. 6. No appreciable advantage can be obtained from close fitting piston skirts which will be attended by a reduction of the mechanical efficiency. 7. With a low oil consumption engine smoking exhaust when light running is usually caused by leakage of oil down the valve stems. Valves should therefore contd. | ||