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 stripped after a 25,000-mile test run on Aero Shell oil.
| Identifier | ExFiles\Box 179\2\ img033 | |
| Date | 1st December 1931 | |
| ORIGINAL To R.{Sir Henry Royce} from Hm{Capt. W. Hallam - Head Repairs}/Rm.{William Robotham - Chief Engineer} c. SG.{Arthur F. Sidgreaves - MD} c. WOT. c. GM. HV. He/Rm.{William Robotham - Chief Engineer}1/ADJ.12.31. X7941. X544. 25-EX - 10,000 MILES. The following were the main points in connection with the strip of the above car at the completion of the 25,000 miles running on Aero Shell oil :- ENGINE UNIT. The engine generally when stripped was in a very clean condition with the exception of a deposit in the crank-pin bores which we get after every 10,000 mile test but which never seems to build up sufficiently to choke the oil holes. To prove this point we have re-erected the engine without removing this deposit and are proposing to do another 25,000 miles to see if connecting rod failure occurs due to shortage of oil to the big end. The deposit with this oil was perhaps slightly greater than with XL. The condition of the engine components was as follows :- Auto Klean filter - Good condition Crankcase - No cracks Main bearings - The centre main bearing cap was broken. This caused excessive wear on the centre bearing which suffered in consequence and the increased load on bearings 3 and 5 caused white metal to break away. The other bearings were in good condition. Crankshaft - This was in remarkably good condition and showed very little sign of wear. Connecting rod big end bearings - A small portion of white metal broken away from Nos. 3 and 4. Otherwise in very good condition. Cylinders - Attached is a complete analysis of the cylinder wear. These cylinders have done over 30,000 miles. We consider that this wear is remarkably slight for the mileage run and attribute this largely to the extra oil which supplies lubrication to the cylinders when warming up. Pistons - The general condition of the pistons was fairly good. Several ring stops were loose and one stop had disappeared. The scraper ring groove in the oil holes on the pistons were rather badly carboned up, No rings were actually gummed up completely. Generally speaking, the other parts of the engine were in very good condition. | ||