Diesel in the sump?

[Mike Banks]

It is more likely to be leaking from the return line for the diesel. This happened to me--I wondered why the bilge pump started--noticed it was pumping out diesel fuel. Replaced return hose--problem fixed.

[Celestialsailor]

Originally Posted by jmschmidt

Due regular oil analyses of your engine oil at Blackstone Labs. Less the $30, free sample collection container, free sample mailing in the US. Email message with the completed report and a charge to your credit card will arrive in a very few days.

I have this problem. The oil analysis indicated that my 40W oil cold was only 30W due to dilution with diesel fuel. But when heated to operating temperature the 30W was now only 5W. Big problem. The rest of the report indicted normal or no traces of other contaminates. The compression check showed a bad valve, only 100psi in #4 cyl. No metal in the oil was good news so I'm hoping no ring damage and just unburnt fuel finding its way into the crank case due to the nonfiring cylinder. Otherwise big bucks.

When ever I have had to rebuild a diesel engine, it has alway been cylinder #4 that showed indications of corrosion or premature wear. I believe this was because it was the closest cylinder to where the salt water is injected to the exhaust.

[PedroPV]

Thank you all. You've been very helpful and informative. The oil is not milky and so it is not water. Is looks clear and thin, and so I believe it is probably diesel. I'll try to have a sample analysed, and will keep controlling the level every time the motor works.

The fuel tank is higher than the motor and so I will shut the fuel valve when I leave the boat. Could gravity have something to do with it?

[Stewie12]

I very much doubt if gravity has anything to do with it. As I mentioned before it is probably the seals on the injector pump that are worn and allowing diesel to pass into the sump. They are special seals which are resistant to diesel, so make sure you get the manufacturer's replacement seals. If you continue to run the motor you may cause wear and tear as the oils has been thinned by the diesel.

[Wotname]

Originally Posted by PedroPV

Thank you all. You've been very helpful and informative. The oil is not milky and so it is not water. Is looks clear and thin, and so I believe it is probably diesel. I'll try to have a sample analysed, and will keep controlling the level every time the motor works.

The fuel tank is higher than the motor and so I will shut the fuel valve when I leave the boat. Could gravity have something to do with it?

I think it is possible that a gravity tank could exacerbate an existing leak.

I suspect the OP's engine does not have any seals in the high pressure injection pump. Rather it has a very close fitting plunger and barrel Bosch style injection pump. These wear slightly but this does not normally cause an issue most of the time. However with a gravity tank supplying a slight positive pressure and with the stationary governor holding the fuel rack open, I could see the potential for fuel to slowly leak into the sump.

Disclaimer - I don't have this model engine so the above is only a possible theoretical explanation and maybe is incorrect.

[Celestialsailor]

Originally Posted by PedroPV

Thank you all. You've been very helpful and informative. The oil is not milky and so it is not water. Is looks clear and thin, and so I believe it is probably diesel. I'll try to have a sample analysed, and will keep controlling the level every time the motor works.

The fuel tank is higher than the motor and so I will shut the fuel valve when I leave the boat. Could gravity have something to do with it?

Might be a good idea to stop using the engine until you get to the bottom of the problem.

[Cheechako]

Originally Posted by PedroPV

Thank you all. You've been very helpful and informative. The oil is not milky and so it is not water. Is looks clear and thin, and so I believe it is probably diesel. I'll try to have a sample analysed, and will keep controlling the level every time the motor works.

The fuel tank is higher than the motor and so I will shut the fuel valve when I leave the boat. Could gravity have something to do with it?

An oil sample will take a while. Put some in a jar overnight and see how it separates, or... get the valve cover off and see what you see.

[PedroPV]

It looks very much like a fuel leak in one of the injector pumps. I will probably have to have new ones (a lot of €€€). Is it possible to repair the injector pumps, or just have to be changed?

[Wotname]

Originally Posted by PedroPV

It looks very much like a fuel leak in one of the injector pumps. I will probably have to have new ones (a lot of €€€). Is it possible to repair the injector pumps, or just have to be changed?

You can get exchange ones or have the old ones rebuilt.

Here is one example https://www.parts4engines.com/volvo-...pump-exchange/

[wingssail]

Originally Posted by PedroPV

Thank you all. You've been very helpful and informative. The oil is not milky and so it is not water. Is looks clear and thin, and so I believe it is probably diesel. I'll try to have a sample analysed, and will keep controlling the level every time the motor works.

The fuel tank is higher than the motor and so I will shut the fuel valve when I leave the boat. Could gravity have something to do with it?

I had this problem with my Yanmar diesel. The engine seemed to run fine but diesel fuel was getting into the oil sump and diluting the oil. We decided the fuel pump diaphragm was not leaking but we had no idea what was going on, and feared the worst. We were 1000 miles from the nearest reliable diesel mechanic. We bought ALL the lube oil in the local town and every empty container we could find, and set sail for Australia mostly sailing but still running the engine daily to charge the batteries. We changed lube oil after every 4 hours of engine operation.

In Scarborough the mechanic found an injector tip blown off, which allowed excess fuel into that cylinder, which got past the rings and into the sump. Injector shop serviced the injector and all was fine.

How did the injector tip get blown off? We had just run the engine motoring for 30 minutes at full throttle (3400rpm) because we had always been advised that you need to do this periodically to keep from glazing the cylinders and to prevent other problems (lol) but apparently some water from the fuel tank got past the water separator and into the fuel system and turned to steam in the injector and blewie.

I don't follow many of those old "you should always..." saws any more.

[a64pilot]

I moved the thread from forum tech support to the engines section.
But I agree, it’s fuel, water will be immediately apparent in any quantity, it turns oil very milky.

[acem]

Be careful here. I farm for a living and mechanic on the side, sail when I can.

I have had and seen diesel engines lock up because of diesel entering the oil.

Your best solution is to remove the injectors and injector pump and take them to a good repair shop that specializes in diesel injection systems. Avoid using the engine until then.

As a temporary crutch you can change your engine oil very often, preferably with a heavier than normal oil. The diesel thins out the oil.

Also check your fuel return line. I have seen these plug, blowing the seal in the injector pump, causing the fuel to leak into the oil.

Thx-Ace

[PedroPV]

Acem, thanks for the advice. I agree. I just have changed the oil and have now the Volvo oil brand (15-40). Now I am in contact with a lab specialised on fuel, oil, etc. quality. They asked for +/- 1 litre sample and will check whether there is diesel and/or water in it, acidity, etc., and the correspondence (or not) to the characteristics announced by the supplier. This will give me certainty about contamination.
Then I will contact the Volvo agent for exchange injection pumps, or send the injector pumps to be serviced (if possible).
I tested the inline pump by disconnecting the IN line bloking it with my finger and puting it to work manually. Suction was very much there, and so I conclude that the membrane is well and there is no leak. I dare not to use my finger (or any part of my body) to check the injection pumps !!!

[Compass790]

Originally Posted by PedroPV

Acem, thanks for the advice. I agree. I just have changed the oil and have now the Volvo oil brand (15-40). Now I am in contact with a lab specialised on fuel, oil, etc. quality. They asked for +/- 1 litre sample and will check whether there is diesel and/or water in it, acidity, etc., and the correspondence (or not) to the characteristics announced by the supplier. This will give me certainty about contamination.
Then I will contact the Volvo agent for exchange injection pumps, or send the injector pumps to be serviced (if possible).
I tested the inline pump by disconnecting the IN line bloking it with my finger and puting it to work manually. Suction was very much there, and so I conclude that the membrane is well and there is no leak. I dare not to use my finger (or any part of my body) to check the injection pumps !!!

Before you rush off to get new injection pumps ( they are expensive on a Kubota, probably a kings ransom on a Volvo ) I'd do the simple things first.
Check your valve clearances & compression first, especially if the motor is running a bit rough. Also injector spray patterns & pop test them.
Others suggest return line can be a problem
FWIW buying Volvo oil wont make any difference except to your wallet. Volvo dont make oil, they just rebrand oil that meets their spec & put a big markup on it.
I don't have your engine this is just general diesel suggestions

[PedroPV]

Valves and injectors were already serviced and are alright. Cylinder compression and fuel lift pump also
If (big if) there is a problem related to injector pumps, I will call the local Bosh service to see hat has to be done.