Oil level "Rising"?

[prof_mariner]

Hi,

I've got a Perkins 4108 diesel engine with unknown hours. Had it inspected last year when I bought the boat and it passed with flying colors. I've not used the engine much since, but run it about once every couple of weeks as a matter of routine.

A few weeks ago when I checked the oil level it was higher than the recommended level and the oil seemed thinner. The oils color was black but didn't smell particularly different from other oil. So I pumped out the excess oil until it was exactly at the required level. Today I checked the oil level and, again, it was above the required level. Still black in color but smells kind of like lighter fluid. I ran the engine for a few minutes and noticed a small sheen of fuel coming out of the exhause. I also noticed that one of the brass fuel line connections (between the tank and the fuel pump, but in the engine compartment) has a very minor leak. I can only think of two things that would cause the oil level to rise, a blown head (allowing coolant/water into the oil pan) or a fuel leak. I suspect that somehow fuel is leaking into the cylinders while the engine is turned off, and that fuel is ending up in the oil pan.

Any idea what might cause this and how do I fix it? Could it be that minor leak in the fuel line? Or a defective fuel pump?

[S/V_Surya]

Oil level rising could be from a few sources. Mechanical Fuel pump diaphragm, coolant (but oil would be foamy looking). injection pump to name few. First get oil analyzed by Blackstone labs. Check or replace fuel pump they are cheap. If it is the injection pump get ready to spend some serious cash.

[jstevens]

One other potential source of a leak into the oil is from the oil cooler. It may be more expensive to have the oil cooler tested than it is to just replace it.

John

[DeepFrz]

I would check the mechanical lift pump first. Often the pump membrane will leak diesel into the oil pan. Next guess would be high pressure pump oil seal. The oil cooler, if you have one, can be bypassed to check that out but if it was leaking the oil would be a lighter coffee with cream color.

[prof_mariner]

Thanks, sounds like you guys are thinking along the same lines as I am. It's got to be fuel (and not water or coolant) as the oil color is jet black, just thinner in viscosity.

Is there a way to test the mechanical pump without just replacing it?

On other boats I typically secure the fuel supply when the boat is not being operated. The fuel shut off on this boat is in an awkward spot to get at so I've been leaving it open.

What are people using for oil on small diesels now a days? Last time I changed the oil I used SAE 30, but someone else said that a multi weight (like 10W30) is now the norm? I've not owned this boat that long and have probably put maybe 10 hours on it since the last oil change.

[a64pilot]

Delo or Shell 15W-40 is real common good oils and easy to find.
Nothin wrong at all with straight 30 though nothin at all
I'd change oil and get that fuel dilution issue fixed ASAP enough fuel in the oil can cause the engine to run away.
My vote is mechanical lift pump easiest and probably cheapest too


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[prof_mariner]

Thanks, agreed. Fuel line and engine are secured until I sort this out.

Where's a good place to find a Perkins 4.108 mechanical fuel pump here in the US? Started to search the internet but the suppliers I'm finding are all in the UK.

[DeepFrz]

Most mechanical lift pumps can be dismantled and often you just need to replace the membrane. You should be able to see if it has failed by holding it up to a light.

http://www.swdieselinc.com/lift_pumps_s/66.htm

[boatpoker]

Originally Posted by prof_mariner

Thanks, agreed. Fuel line and engine are secured until I sort this out.

Where's a good place to find a Perkins 4.108 mechanical fuel pump here in the US? Started to search the internet but the suppliers I'm finding are all in the UK.

Try any farm equipment outfit. I rebuilt a lift pump once (diaphragm and gaskets). The rebuild kit was $4 less than a new pump.

[lancelot9898]

www.tadiesels.com is another source. I too have the 4-108 and it being 29 years old I suppose I should be more proactive in replacing things. I assume these pumps come with the mounting gaskets and wonder if just replacing the diaphram might be sufficient rather than buying the whole pump?

[lancelot9898]

Thanks boatpoker...you answered my question.

[boatpoker]

Originally Posted by lancelot9898

www.tadiesels.com is another source. I too have the 4-108 and it being 29 years old I suppose I should be more proactive in replacing things. I assume these pumps come with the mounting gaskets and wonder if just replacing the diaphram might be sufficient rather than buying the whole pump?

Many of these pumps are now made in China with the top plate riveted to the body. for another $4 .... go with a new pump rather than hammering away on rivets.

[a64pilot]

I believe Massey Ferguson used many Perkins engines, I bet if you take the pump in hand and tell them it came off a Massey Ferguson, you'll get a pump.
I don't know which tractor model used your engine, but that would be a real help

[Capt Doug]

Oil level rising, I just had that conversation with myself last week. Checked the closed cooling tank, "empty". I guess that anti-freeze will mix with oil and not turn milky, like water and oil. Pulled the head, bad news, head gasket looks perfect. any ideas where to look,test next. OH yah Perkins 4-107 circa 1974

[lancelot9898]

Just another thought...Maybe that 29 year old pump is a better pump than the new ones made in China??