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 potential solutions for piston seizures on Bentley cars.
| Identifier | ExFiles\Box 86\1\ scan0150 | |
| Date | 4th April 1935 | |
| 4219 To ag. & WOP. c. to E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Rn.{Mr Robinson} c. to MX.{John H Maddocks - Chief Proving Officer} c. to Hd.{Mr Hayward/Mr Huddy} Piston Seizures on the Bentley. We have now had about a dozen cases of piston seizure on the Bentley in customers' hands. These seizures are very disconcerting as the car is put out of action and frequently a new cylinder block has to be supplied. The moral effect on the customers is of course disastrous. The extraordinary thing about these failures is that although the Bentley and the 20/25 are very similar, a case of piston seizure on the 20/25 is almost unknown. Furthermore, we have failed to reproduce the seizures on our experimental cars or test bed running, in spite of making every effort to do so. We reported on possible solutions to the trouble in HS{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1d/KH.2.11.34. We have had no success with the anodic treatment of the pistons and we do not feel that the Acrolites are going to eliminate such failures. We are therefore left with the extra piston lubrication when starting up, which successfully completed 10,000 miles on 21-G-IV. In view of the recurring trouble we are proposing to standardise this. It cannot be used on cars that have not drilled up connecting rods. We do not intend to groove the big end, but only to allow the oil to feed to the cylinder wall through the two holes already existing in the bearing. This will give us less cylinder wall lubrication than we had on 21-G-IV, but more than on the standard Bentley. On 21-G-IV the effect of supplementing the piston lubrication by this modification was to increase the oil consumption by about 50 miles to the gallon. The present Bentley oil consumption is so exceptionally good that a slight increase is preferable to seized pistons. Piston lubrication from the big end is of course common practice on American Cars, and is fitted to the Buick that we have at the Forge. HS{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} | ||