A bit beyond the remit of this group, perhaps, but anyway.......
I was called out to look at a Kelvin T6 (1964, around 200 bhp @
1000rpm AFAIR) this morning which the barge captain was a bit concerned about as it had started 'blowing' from somewhere yet to be identified. There was a definite 'chuffing' from the air intake which shouldn't have been there, apparently an inlet valve blowing somewhere. It turned out to be No.6 cylinder - this one had blown a head gasket last year, so I had had the valves refaced & lapped in while the head was off, as well as having the head face skimmed. This was the only substantial work the engine had had done to it since I did a 'medium overhaul' at least 15 years ago (new liners, pistons regrooved & new rings, heads overhauled & refaced etc). Of course my first thought was 'why that cylinder?' - had I done anything wrong, etc., though it's performed happily for the last six months. Watching the valvegear with the engine on tickover (~200 rpm) the inlet could be seen to apparently open slightly immediately after closing, for no obvious reason - plenty of tappet clearance etc. To cut a long story a bit shorter, the only rational explanation I could come up with was that the cams for that cylinder have slipped on the shaft. This assumes a built up camshaft, I haven't the manual at the moment so I don't know for sure yet. The valve reopening is,according to my theory, because it is being sucked open on the induction stroke. If that's the case, and *if* (also don't yet know, but it looks likely) there is major work to to to get access to the cams (maybe gearbox {3/4 ton} & flywheel off, etc), I intend to propose to the owners disabling that cylinder temporarily, by removing the valve rockers & diverting the fuel into a container, on the basis that 5 cylinders will give ample power for the time being. An unplanned lengthy period out of service for repairs could be disastrous, so this would enable them to keep running for a few weeks while something can be worked out. I would remove the valve rockers in case the cam slips again, to avoid the risk of valves & piston makeing contact. I'm looking at it again tomorrow, better prepared, and with the manual, and will check the valve events etc to establish whether I'm right or wrong. If wrong, it should just be a simple matter of taking the No.6 head off again :-(Any comments, adverse or otherwise?
Cheers Tim
Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs