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).
Increased oil consumption on a Bentley chassis after the introduction of a larger oil pump.
| Identifier | ExFiles\Box 114\3\ scan0160 | |
| Date | 13th August 1937 | |
| GWH.{George W. Hancock - Head Chateauroux} (K). BY.3/G.13.8.37. BENTLEY CHASSIS. RE: INTRODUCTION OF LARGER OIL PUMP. Referring to our conversation on Thursday afternoon, the 12th inst. on the subject of the introduction of the large oil pump, when you pointed out that a chassis which had an oil consumption of only one gallon per 1600 miles increased its consumption to the extent of one gallon in 260 miles and a re-test with the original pump confirmed the original consumption, it occurred to us in discussing the matter at Derby that the possible explanation was that since all oil which passes the relief valve is distributed through the accessories i.e. there is no direct return to the crank-case, it seems possible that if the grummets were worn on the valve gear that sufficient oil might be supplied with a large pump to the head itself to permit oil to flow down the inlet valves and so increase the consumption. We are making some experiments to confirm this, but mention the matter so that in the event of a similar case occurring you might check this particular point by fitting new grummets. It was confirmed that in fitting the large pump that nothing else was done to the car, the cylinders etc. were untouched, and therefore the explanation could not be the piston rings being refitted wrongly. It was confirmed later that the increase of oil pressure was 5 lbs. throughout the working range of the engine. BY.{R.W. Bailey - Chief Engineer} | ||