Diesel in the sump?

[mvmojo]

Originally Posted by markcouz

Disclaimer: I am no mechanic!

I had a diesel vehicle (Mitsubishi Triton) which for some reason (after injector service so mechanic reluctant to explain it) allowed diesel fuel from above the piston to blow past the piston rings into the crank case, causing oil level to rise.

This went unnoticed until the excessive oil level in the crank case resulted in the reverse happening- diesel/oil from the crank case blew past the rings resulting in runaway engine, excessive rpm, some engine damage.

If your oil level is rising then find the cause fast. I was able to stall the engine by putting in 5th gear and applying brakes, not sure how that would work out on a boat!

Note: if it happens you would need to cut intake air which may be difficult to do in a hurry.

I'll echo this, find the source of the fuel getting in your oil and get it corrected before using the engine anymore. A runaway diesel, where the engine starts sucking oil from the sump and burning it as fuel will quickly destroy the engine. Cutting off the fuel supply will have no effect, nor will pulling back on the throttle. Since on a boat you can't substantially change the engine load to stall it, the only realistic way to kill the engine is to cut off the air supply. It's not a bad idea to have a flat board nearby that you can slam over the air intake if you get a runaway condition. Don't use a blanket, rag, etc. (especially if it's a turbo), the suction is very high and you can end up sucking the rag into the intake manifold!

[lituya1617]

Oil does not grow in an engine sump! This is an emergency situation for your engine. The additional fluid is either water or diesel fuel. Check the sump lube oil for viscosity and water. If it has water in it, it will look milky after running. You may have a crack in a casting or a blown head gasket that allows water to enter the engine. If your cooling level stays constant, water is probably not the issue. You have to fix it immediately if it is water. Water will destroy your engine. If the viscosity is much lower than the lube oil (usually it will pour like water if it is half again too full), diesel is getting in to the base. One common place for this to occur is through a crack in the engine-mounted fuel pump diaphragm. Diesel only very, very rarely enters through a blown injector and you should see it and smell it in the exhaust water if such is happening. It will make an oil slick around your boat. Repair the injector and you are good to go if this highly unlikely cause is found. A neat check for diesel in the sump is to drop a drop of oil on notebook paper and watch it for a few seconds. Diesel will cause the drop to spread rapidly into the paper and form a "fried egg" appearance: a dark "yolk" surrounded by a lighter "white" because the diesel oil wicks rapidly leaving the heavy molecules and carbon behind.

[ferrofan]

Originally Posted by PedroPV

My volvo penta 2003 never needs oil. To the contrary, it looks like creating oil in the sump, as its level goes higher and higher. The inline fuel pump is not leaking to the sump. Could it be the high pressure injector pumps? How is that possible?

I had a similar problem with my old perkins, it was the seals on the highpressure pump. The mechanic in the boatyard said he'd seen it before on another boat and they kept running the engine which set on fire when enough diesel had got into the oil.

[wingssail]

Originally Posted by lituya1617

One common place for this to occur is through a crack in the engine-mounted fuel pump diaphragm. Diesel only very, very rarely enters through a blown injector and you should see it and smell it in the exhaust water if such is happening. It will make an oil slick around your boat.

Yes to the above. I've had the problem of diesel in the sump twice.

Once it was a blown injector tip. Yes there an oil slick around the boat. Yes you could smell it in the exhaust water.

The other time it was a pump diaphragm. Checked twice by mechanics, but I found it by holding it up to the light. Pin hole.

[winklepicker22]

I had the same problem with an IVICO 90hp diesel. If it was water, the oil would foam up. A sump making oil means diesel is leaking past a seal in the injector pump. The only other possibility is an injector spitting diesel rather than atomizing mist... Mine was the front seal. Works perfectly now after the diesel doctor reconditioned the injector pump. My first attempt at a cure was a new lifter pump because it is block mounted and the rubber boot may have developed a pin hole. No such luck...

[HappyGuy]

Many moons ago when I was doing my engineering apprenticeship at the Main Roads Dept base workshop in Brisbane, Queensland - one of the guys was sent out to see what was wrong with an International bulldozer engine out on site.
The Italian driver said "You know good engine, she not use much oil. Bad engine, she use lots of oil.
My engine she extra good engine - she make oil"

He was having to drain a pint or so of oil from the crankcase every morning before starting up.

Turns out the rings were so badly worn that diesel fuel was getting past them into the sump.

[Algee]

Haven't worked on that Volvo engine.
Check out the excess fuel return, some engines route it through the rocker cover first. If this is your system, a leak here would/does start to fill the sump.
I hope that is the problem, it's a cheap fix. As others have said it needs sorted quickly or it will be expensive.

[Shaneesprit]

Hi
As you said correctly in the Sump lol ��
I assume your English?
Most of the advice here is good - get the oil out, ASAP if you are still running the Engine.
Sample is always good but sounds like you know it’s diesel anyway so, little point in sampling until you fix the issues - lift pump or injectors unless it’s running rough ( misfiring ) low load running can also cause this but not normally to the extent that you say the level is high, but if your not topping the oil up or it’s not using any at ever, then you can be sure it’s getting topped up with fuel.
Worldwide big machinery dealers such as caterpillar or Volvo dealers will all offer oil sampling. If your ever stuck best place to look.

[patmvcr]

I had the same issue with my Yanmar 4JH3-TE a few years ago. Ended up being injectors not misting... fuel not being burned... wound up in the oil. A full injector servicing fixed the problem.