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).
The condition of an engine with a knock, detailing a seized big-end bearing and crankshaft damage.
| Identifier | ExFiles\Box 146\5\ scan0103 | |
| Date | 21th February 1939 | |
| Handwritten: Swell. Pitt tok rings 1245 What do we suggest to prevent breakage. 3 1/2 Litre Bentley msg? Pm Typed: To Rolls-Royce Ltd. Derby.......... By Copy to C. London Fm. Derby Ltd. Levallois Sr/VAI/ET.21.2.39 Re: CHASSIS N° 3.BU.144 Lord SOMERS ============== (Mileage: 36.165 miles) COMPLAINT Knock in Engine ============== REPORT UPON CONDITION OF ENGINE ========================== Lord Somers' Head Chauffeur brought us the above car on the evening of the 15th instant, informing us that a bad knock had developed in the engine while he was driving the car from the South of France, en route for London. He said he thought the knock was coming from the tappet mechanism. Upon listening to the engine, we at once diagnosed it as being a bearing knock. The driver informed us that the engine had not been run short of oil. We found plenty of oil in the engine when the car arrived at our Workshops. We have dismantled the engine and the following is our report: BIG-END BEARINGS =============== N°3 big-end bearing seized (white metal melted) on the crankpin as well as the strap rod. The strap rod is damaged and will have to be changed. The other big-end bearings are in very poor condition, especially Nos. 1, 2, 4 and 6. There is a very large chunk of white metal missing from the strap rod bearing on N°5. We are to-day returning the dismantled rods to the Works, and have labelled them for your attention. CRANKSHAFT (Please refer to Sr/VAIS/ET.20.2.39) ============================================ N°3 crankpin very badly worn, scored and ovalized. Maximum diameter = 2.2475" and minimum diameter = 2.231". Remaining pins O.K. re wear. Please refer to attached sheet showing measurements of crankshaft. It will be necessary to change the crankshaft or for us to have the crankpin ground to a smaller diameter, approximately .040" undersize, have the crankshaft re-nitrided and fit | ||