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).
Letter detailing an engine seizure and oil pressure issues on Chassis B.8.GA during the Paris Trials.
| Identifier | ExFiles\Box 146\2\ scan0135 | |
| Date | 1st February 1937 | |
| To Bentley Motors Ltd. Derby............... Rm.{William Robotham - Chief Engineer} Levallois Sr3/ET.1.2.37. Re: CHASSIS B.8.GA - PARIS TRIALS CAR. I have just come back from giving my B.8.GA a trial, and the inevitable has happened, at least I presume so, in other words: I seized the engine. To all intents and purposes, I presume it is N°7 main bearing which, you will remember, we left in to experiment further with R.R.56. We will shortly give you a report on this matter, as I am having the sump removed immediately. The engine seizure was exactly similar to the last one and occurred after approximately 7 Kms. of fast running, the seizure becoming apparent on this occasion at 4350 to 4400 revs. I immediately cut off, etc.., but before coming to a standstill, I let clutch in again and the engine got un stuck, and off I went again. On this occasion it started seizing again at 4000 revs. I thought it would be interesting to see what happened if I kept going. You will be interested to hear that the engine gets tighter and tigher, until one presumes it is time to cut off. After we had let the engine cool down, we found it impossible to start off again, but after pushing the car with another car, we managed to unseize it and I came back quite happily. In fact if the engine was not now slightly on the stiff side, one would not know anything about the seizure in question. I am therefore going to replace the bearing by a standard Hall's Metal. Now I should like to point out to you something which I consider is likely to lead us into difficulties. As you know, on my car the crankshaft has been drilled and I am convinced now, from experience, that with these extra holes and Hall's Metal clearances, it is not possible that the present oil pump can maintain anything like the prescribed pressure once the oil has got really hot. My oil pressure on the above mentioned occasion was between 16 and 17 Lbs. when the engine seized. Prior to seizing, I had after a run of 50 Kms. at speeds varying between 4000 and 4200 revs, stopped the car to check up the oil pressure when slow running, and I found this to be as low as one and half pounds at approximately 400 to 450 revs. The oil pressure when running at 4200 revs during these 5 Kms varied between 22 and 27 lbs. I went off again, and the further I went, the lower the oil pressure got, until the accident occurred. para N°9 | ||