4D61 oil leak

[motthediesel]

I have been fighting a consistent oil leak on our old French rattler. It seems to be coming from the fuel lift pump. (I'm talking about engine lube oil leaking, not fuel) I have cut a couple of fresh gaskets, and slathered them well with gasket compound -- and while this has slowed the leaking, it has not stopped it entirely.

Is it possible that the oil is coming from the body of the pump itself? I doubt I'm going to find that unit anywhere in the US, so I'm thinking of making a blank-off plate and bolting it on. Then I would fit a small electric lift pump in it's place.

Anybody else had this same problem?

Tom

[WillieC]

The pin that the actuator arm pivots on is on the oil(engine) side of the diaphragm (if it is like most fuel pumps). A sloppy fit there could produce oil drip.

I am not familiar with the 4D61, just old mechanical fuel pumps. Your thought as to a blanking plate and electric pump may head off future problems and make bleeding much easier. (I installed an electric pulse pump in line with the mechanical. This is on the Volvo Penta 36HP MD17C. An improvement would be to install the pumps in parallel with appropriate valving, and more places to leak. Keep us informed.)

[motthediesel]

Just to close out this thread—
I made a blanking plate to replace the mechanical lift pump. It was a little tricky though — unlike any other mechanical fuel pump I’ve seen, this one is driven by a small button that projects out of the engine block. So, the block needed to be thick enough to allow a clearance hole to be drilled in the back for the “button”.
I made the cover out of 1/2” aluminum stock, back-drilled to give space. I then added a mount for a Facet 12v pump. I powered that from the same circuit that energizes the injection “stop” solenoid.
That worked fine, and it greatly reduced the oil leaking, but there clearly was still some oil leaking from the same area.
I cleaned it up again, warmed the engine up, and watched very closely to see where the oil was coming from. I was surprised to see a shiny ring starting to form around the chrome acorn nut just below the fuel pump mount. What is that nut even for?
I put a 17mm socket on it, and I could turn it off with my fingers! The nut was screwed onto a hollow rod, and the washer under it looked like a copper “banjo bolt” washer. Located right under the exhaust manifold, I wonder if that point is put there to provide oil to the turbo in engines that are so equipped?
Anyway, I tightened it up, took it for a pretty good ride, and low and behold — no oil in the bilge at all! So, for now anyway, no more “bilge diapers” needed — on to other things on the punch list!

Tom

[WillieC]

Excellent news! Don't you love actually fixing something on the boat?!
Nicely done.