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).
Engine issues including torque dampers, oil system, and multiple piston failures.
| Identifier | ExFiles\Box 179b\4\ img018 | |
| Date | 9th April 1933 guessed | |
| -5- until in our opinion would not be passable after the engine had become hot. In the second and third gears it was most pronounced. A knock developed in the torque reaction dampers when the engine idled and slow running was uneven, the out of alignment of the dampers was the cause, which was cured. There has been no marked torque reaction period. The engine remained free from detonations by the use of Esso petrol, which is a benzoline mixture only. Preignition was only noted once, through a weak mixture obtained by the failure of the petrol supply. The breather to the crankcase we found to be inadequate, and was the cause of the engine burning unnecessary oil The oil being drawn up the breather pipe. This was cured by an adaption being fitted to the crankcase oil filler which made it the same time retaining its capacity as an oil filler. An increase of 200 miles was obtained in oil consumption. A sketch has been previously sent to Derby. The rocker cover joint has been very poor for retaining oil. The quantity of oil escaping down the cylinder block makes a very dirty engine after a long sustained run. PISTONS LOP. E.{Mr Elliott - Chief Engineer} 55804. E.{Mr Elliott - Chief Engineer} 56610. As reported there was an exhaust blow into the crank chamber when the car returned from Mr. Bentley's trip. When dismantled the failure was found to be the pistons, the retaining split pins had worked out and the chattering had caused excessive wear of the pistons, at the ends of the gudgeon pins. The cylinder bores were also damaged. A new cylinder block and pistons E.57122 were fitted. Two of these pistons broke very quickly, the head parting from the skirt. It was found that the pistons were weak in tensile strength, which was the cause of the failure. A new set of pistons E.56610 were fitted made in the correct material. These pistons gave no trouble until 4,877 miles had been run. It was then discovered upon draining the oil out of the crankchamber that a portion of a piston skirt had broken off. There had been no indication whilst driving the car that anything had happened. Upon dismantling the engine it was found that No.3. piston had a section of the split skirt broken. It had broken from the cross cut diagonally downwards. It did not in any way affect the running of the engine and did not cause any damage. The other pistons were taken out, cleaned and examined, but no sign of cracks or fracture were apparent. The scraper ring on No.4. piston was broken approx. 1 inch from one end. We have had two scraper rings break on this piston. A peculiar feature was noticed with regard to the gudgeon pins. With no exception the six pins had worked | ||