Shortshanks Viewminder: I had that same sound and one day there was a lot of exhaust smell in my cabin and I opened up the engine compartment and I found two bolts in the bilge under the engine... they held the exhaust on and they'd come out... but they were slapping like that for a year... if you have exhaust smell in your boat I'd look at that... I put them back where they belonged and tightened them up and now it doesn't sound like that at all.
Tech Davey: These engines should never wear out unless one lives on the boat and cruises constantly. OK some people run their engines just to charge the batteries but that is a bad idea. Of course the cosmic clock never stops and engines can fail in other ways. (For example marine engines are not built from marine materials!)
As to the knock, there is a chance that its the injector but it could be piston slap, little end play or big end play.
Simon Redfearn: Sounds just like mine!!
Senior Barba: Did you figure out what was causing it?
Bas bjm: we have the same diesel engine in our sailing boat and after 30+ years it still works directly after turning the key. Even after a winter (with antifreeze)
antofa123: Blown head gasket isn't too bad... at least you won't have to strip the block down. Good luck with the rebuild!
antofa123: Mine doesn't have that ringing knock....
fillyerboots1: That tapping sound could just mean the tappets need adjusting, but I'd be interested to know what conclusion you came to, and if you still have this engine. Mine is a 2 year-old 1GM10 which sounds a bit like this upon first start up until the oil gets around the system and it warms up a bit, when it thumps rather than 'taps'..
sailpunk: This does not sound right, the loud knocking is not normal. I have a YSE8 in good working order and that is not how it is supposed to sound. The last comment is likely right however make sure it is not something rattling on the engine. Check the mechanical oil filter for metal.
MrAndrewee: sounds like the piston is hitting the the top. Maybe you need to inspect the engine oil and look if there are parts or dus of iron in it. If so, then ask professional advice, maybe the engine needs to be revised.
sixtyfiveford: Sounds like an air cooled diesel to me. Is it still going strong?
Neil Deverell: great!!!!!!!!!!!!