MD1B oil pressure

[Thad]

You might remember that I had a little problem with oil pressure earlier, solved. Now same problem but different. Sailed for Gloucester Saturday to do the Schooner Festival race. Wind all night had been blowing NE 20-25+ and continued so. We were a little late leaving Marblehead and were running the engine as it was dead to windward. With the slow progress into the seas we hoisted sail and motorsailed. On the starboard tack all seemed fine. When we went on the port tack we got more noise from the engine, dropping pressure, and lost power(maybe from low fuel) so we shut down the engine and sailed as we should have anyway (of course!!). Unscrewing the oil filter later there was no oil pumping to the filter though there was oil in the well. The question is what to do. Do I have to pull the engine to get at the pan and check out the oil pump and pickup, or is there some other way to tweek the thing and break an air lock if that is the problem?
The race (by the way!?) was wild. We were late for the skippers meeting. The committee boat acknowledged our right to race but would not tell us anything about the starting sequence or course. We sailed off into the 8' seas that were often 12'+ coming onto the ledges below looking for marks with the rest of the small fleet that started. Some of the boats did turn long before any others so they may have seen the windward mark, but not us or many others as we sailed on and on. Coming back toward Eastern Point and the finish we did pass what turned out to be the reaching mark on the triangular course, so we certainly rounded the course but sailed at least 3 times the necessary distance. We were not more confused than others who were better informed than we. The sea conditions made seeing a racing bouy chancy at best. Kind of fun in the seas as nothing broke and no one got hurt, but not much of a race. So much so that the committee couldn't announce results last night and say they are going to make some decisions after talking to all the participants they can. As there were no more than two boats that started in our class and we might have been the only finisher we might win by default (or persistant craziness if you take that view). Cheers, and thanks for any engine help forthcoming.

[David]

Hi Thad,

Since I just rebuilt an MD2B (identical to yours but mine has one more cylinder) I guess I'll take a shot at this (from memory so don't rely on this).



First some background. These engines are absurdly simple and can be rebuilt if not too badly corroded since the parts are still widely available (but shockingly expensive). It is likely that you will thrash around hoping against hope that there is something simple wrong but eventually, you will probably come to the conclusion (probably like me when it's in pieces around you) that you must rebuild it. In general, loud noises combined with low/no oil pressure is the diesel engine owners worst case scenario. Don't run it anymore! If you don't have the service manual, I could let you copy mine (MD1B, 2B, and 3B have the same manual) and if you study it you will see that the oil is sucked up from the sump through a draw pipe on the starboard side of the engine. The oil level check is part of the oil strainer that slides into this draw pipe (covered by the brass cap like thing on the starboard side). This cap must be tight with the gasket well compressed or there will be no oil pressure. Next the oil flows through a gallery in the block through the oil filter and next through the oil pump (which up to here is sucking). The oil pump sits on the port front side just behind the fly wheel. The pump itself can have troubles that are fixed by placing shim/gaskets but this is not likely your problem. The oil is then pushed through holes in the block and crank that feed the main (there are two on yours), cam shaft (two) and big-end (one) journal bearings. These bearings are made of a soft lead-bronze material mounted on bronze shells that melts catastrophically if the oil pressure drops. (Don't ask me how I know this!) Otherwise, as they wear down, the oil pressure drops slowly until not enough oil is flowing somewhere over some downstream bearing surface and, yes, it fails. When this happens if you stop running the engine in time so that the crank shaft bearing surfaces and cam shaft bearing surfaces are not scored, the fix is to replace the bearings which requires tearing the whole engine apart (not really that big a deal if you aren't in a hurry but would cost a lot to have a mechanic do it for you). If you continue to run the engine with low/no pressure, the cam shaft and crank will be hopessly scored and the engine is toast.

I haven't answered your port/starbord question but I suspect that you will have found by now that it doesn't matter and that the oil pressure is gone. If the pressure is fine at anchor then something funny is going on with the draw pipe but I doubt it. By the way, there is no pan on these engines, you gain access through the removable side panel.

Removing the engine is easy if its located close to or below the companion way -- place a 4x4 across the opening and use a come-alone attached to the eyebolt on top of the cylinder head. Be carefull, it weighs a lot so you need come-alongs (a crane would be nice too!).

Let me know if you need more info.

Good luck,

David.

[Alan D. Hyde]

I don't know these engines, but I take it from the above discussion that it isn't a clogged screen on the oil pick-up.

Right?

Alan

[Trog]

Should it prove helpful, I can scan and make available for you:

MD1 Marine Diesel Engine Instruction Book

D1 - MD1 / D2 - MD2 Workshop Manual

MD1 Reservdelskatalog / Parts Catalogue

None are specific to the B model, of which I am not familiar, but may be useful nonetheless.

[Thad]

Thank you all and David especially. As it happens I have not run the engine since Saturday, yesterday I brought her in and we hauled her out, today I hauled the engine out and brought it to a mechanic to investigate. I do have the manuals, thanks for the offers. I did find that the motor mounts were basically floating and have a couple of hull issues to deal with that helped inspire me to go for the haul out. I do like the engine and expect it will come back as good as ever and better mounted. Thanks.