We motored for about 6 hours yesterday. Halfway thru the trip I took a good look around the engine and everything looked OK. After we got in I happened to look again and noticed a stream of oil running under the engine (perhaps a cupful or two of oil, though it seemed a lot more at the time). I traced the leak back to the oil pressure alarm sender. I tightened it onto its bronze T joint, which took about a quarter turn, and it doesn't appear to be leaking any more.
Going from what looked like a potential disaster to a simple 10-minute fix seems almost too good to be true. But I'm wary about what caused it to leak in the first place and whether I have to worry about it happening again. When I had the engine hauled last year the yard broke off the old oil sender and alarm assembly, so I replaced the nipples and bronze T fitting using 1/8 BSPT (British standard pipe tapered) which I understand is the Yanmar standard. I didn't use any gunk because it needs metal to metal contact for the electrical ground. Perhaps I didn't tighten it enough last year, but in that case I would have thought it would have started leaking before now. I did have to back hard when pulling into the dock yesterday due to a strong current, would that have raised the oil pressure and started the leak?
Needless to say I'll keep a close eye on this, but curious if any of you with a mechanical bent have any feedback on this issue.
Thanks,
Max (currently in Brighton, UK)