I have a old 1953 starto-matic generator with Petter engine, I ran it for about 6hrs three months ago when work was being done to main lines, at that time hadn’t been run for a few years and before I started it ran all the diesel out and changed the oil and ran as normal. There was a intermittent line fault for a few hours a few days ago, so batteries were still there and like always a instant starter it fired up, however instantly very load air intake noise of a load thots at 850 thots PM, so ran it down and looked at the valves, clearances fine and checked valves rocking at TDC with lift amount all normal and injection timing seems ok as it always smokes a little for few minutes until hot. If it was a Lister with alloy head I would start to think valve seat starting to loosen and drop and if it was that it would quickly and suddenly go clicky clack knock knock and end of that engine, its a cast iron head so might not be inserted. I was always working on the high speed Listers units but never overhauled the Petters. I do have the hand book with the so called updates as it was one step forward and two back as the early ones that I have has external oil pipes to both main bearings, apparently when they dropped to just one pipe as with big end bearing wear starved the main flywheel side and cased early failures.
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