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).
Causes and investigation of high oil consumption on Bentley vehicles.
| Identifier | ExFiles\Box 144\3\ scan0041 | |
| Date | 11th March 1936 | |
| X1220 To Hd.{Mr Hayward/Mr Huddy} c. to K.{Mr Kilner} c. to P. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}12/KW.11.3.36. Oil Consumption on the Bentley. We are anxious to get all the information we can about the oil consumption on the Bentley so that we may stop this becoming an epidemic. The top overoiling trouble, due to the rocker shaft being fitted the wrong way round, is now widely known and does not require any further comment as it is easily dealt with. If a car starts out with satisfactory oil consumption, which subsequently deteriorates and causes the owner to be dissatisfied, as far as we know it can only be due to one of four causes :- (1) Piston wear (2) Cylinder wear (3) Ring wear (4) Bearing wear. This assumes that it is always established by cutting off the overhead supply that oil is not getting down the valve guides. If oil is getting down the valve guides with the rocker shaft correctly fitted, then it is a matter for new asbestos grummets or valve guides. We have no experience of undue cylinder wear taking place on a car in less than 35,000 miles, and even at the end of that time the oil consumption was over 600 m.p.g. when driven very hard. The cylinder wear was confined to the extreme top of the [Piston travel] bore and we attach figures. It occurs to us that the most probable cause of increase in oil consumption is ring wear, or increased flow of oil to the bearings due to increase in clearance. The ring wear can easily be dealt with by measuring the gap. The bearing wear is not so easy to check unless an oil test has been established where the quantity of liquid under even pressure passing the bearings can be measured. We should be glad of all the information obtainable. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||