Crankcase Oil Contaminating Yanmar Diesel Fuel

[hpeer]

Originally Posted by swordds

Oh no, just one 15 gal fuel tank, the other fuel container that I confusingly mentioned is a 5 gal fuel (jerry) can.

OK and thanks.

A final query to to make sure I understand...


The fuel in your 15 gallon tank is contaminated, correct?

SWORDDS wrote

And yes, the fuel return line goes to the lift pump and not directly back to the tank.

[swordds]

* * Thanks Cheechako for the great ideas and sorry for the long response - but I am so happy for the problem support.* Also, one of my generic forum peeves is the long troubleshooting threads that never publish a conclusion, successful or other wise. So my self-goal is to stick with my own thread until their is a resolution. Hence this longish response (also the heat index is 104 Fahrenheit/40 Celsius so a good day to sit in my slip where I can run my A/C).
* * I did keep a separate jar of the dirty fuel for a few days. The contamination (whatever it may be) did not separate out. My assessment was that if it is crankcase oil, the oil is miscible in diesel and so it will not separate?
* * The electric fuel pump idea may be my ultimate fix, especially considering the difficulty in accessing the mechanical pump. My* major concern is that having an abandoned in place non-functional but still operating mechanical pump left on the engine will result in some future problems (e.g. leaking crankcase oil into the bilge).
* * My problem with an electric pump as a temporary fix and a useful addition for fuel priming is that I am relying on another person for help, and doing this while waiting for the new mechanical pump would be an imposition.* The “one step at a time” approach fits their schedule much better than the implementation of a temporary work around.* I know that as a single-handed live aboard person I should be more self-sufficient and should be doing this without depending on outside help but I am somewhat elderly, I do not have transportation (other than walking and sailing) so gathering parts and materials is an effort, and I do not care to own other than the most minimal amounts of tools and equipment. So for now I will store the temporary fix as a great idea (!) while I continue to wait impatiently for the new pump.
* * I look at the mechanical breather valve every day thinking I should remove and disassemble/inspect it. But it is a fairly small, complex and delicate looking device with a spring, a diaphragm, a gasket, a baffle and a baffle plate and I suspect that the process of* disassembling and inspecting it is just as likely to damage it as not, and then I will be waiting on another “hard to source quickly” component (complete assembly or diaphragm) so I think I will wait to assess the crankcase pressure when the engine is running, before dissecting this device.
* * At some point (hopefully) in the next week or so I hope to post a summary “ Yanmar Diesel Fuel Contamination Troubleshooting History and Resolution” Quick Reply :-)
And hpeer the fuel in my 15 gal fuel tank was contaminated but that fuel has been disposed of and now my fuel tank is empty and clean. I will refill it with fresh fuel after installing the new lift pump.

[skipperpete]

To get a a quick indication of crankcase pressure, simply remove the oil filler cap while the engine is idling and warm. If you can feel the filler cap pop as you release it or you feel a substantial flow of air coming out of the filler..... that’s blow-by.
It can often be from leaking piston rings but also can be from a head gasket blown across to the pushrod gallery.

[hpeer]

And hpeer the fuel in my 15 gal fuel tank was contaminated but that fuel has been disposed of and now my fuel tank is empty and clean. I will refill it with fresh fuel after installing the new lift pump.

OK and thanks.

Here is what I am thinking. This sketch is what I hear you describing.

If this is NOT the installation then what is different?

Assuming this IS the situation:

I see no way the lift pump can contaminate the fuel in the tank. NONE.

Contaminated fuel can cause your problems.

I find it difficult to measure oil level to within 1/2 quart. It am going to throw this out as a red herring.

Your fuel got contaminated in some fashion. How? I do not know. Maybe some one is messing with you? Poured oil in the tank? Who knows.

But I see no way that the lift pump can cause this problem IF the injector fuel returns to the lift pump and not the tank.

Not trying to he a wise guy, just trying to make sure we understand the situation. Thats why I drew it out, 1 picture a thousand words kind of thing.

Is this picture correct?

[skipperpete]

The 3YM fuel system is meant to return to tank via a permanent bleed on top of the secondary filter. The injector leakoff pipe is tee’d into the injector pump return and the system is self priming provided that the remaining barb ( circled in black in the pic)on the secondary filter is piped back to tank

[Compass790]

Originally Posted by skipperpete

The 3YM fuel system is meant to return to tank via a permanent bleed on top of the secondary filter. The injector leakoff pipe is tee’d into the injector pump return and the system is self priming provided that the remaining barb ( circled in black in the pic)on the secondary filter is piped back to tankAttachment 240432

Ah so what you are describing is a pathway for the fuel that has been through the lift pump & return line to get back to tank.
If that is how the OP's engine is piped up he needs to put a clean fuel supply to his lift pump & take off rtn line & squirt into another container to see if its contaminated as hankonthewater suggested.
However he is set on replacing his lift pump it seems

[Compass790]

* * I look at the mechanical breather valve every day thinking I should remove and disassemble/inspect it. But it is a fairly small, complex and delicate looking device with a spring, a diaphragm, a gasket, a baffle and a baffle plate and I suspect that the process of* disassembling and inspecting it is just as likely to damage it as not, and then I will be waiting on another “hard to source quickly” component (complete assembly or diaphragm) so I think I will wait to assess the crankcase pressure when the engine is running, before dissecting this device.


Yea dont worry about crankcase breather valve if you are not confident in tackling it at this time. It may not be the problem.



In your case with lack of access I would not worry too much about leaving lift pump in situ & just bypass it.

However you have already bought the pump.

[skipperpete]

The possibility of a combination of a leaking lift pump diaphragm and a lot of crankcase pressure still remains as a contender in the “oil in the fuel” situation but it does strain credulity. The only crossover point for fuel oil and lube oil is at the injector pump and the associated lift pump but I have no explanation to offer for the lift pump drinking the injector pump lube oil and returning it to the fuel filter.
Pete.

[Compass790]

Originally Posted by skipperpete

The possibility of a combination of a leaking lift pump diaphragm and a lot of crankcase pressure still remains as a contender in the “oil in the fuel” situation but it does strain credulity. The only crossover point for fuel oil and lube oil is at the injector pump and the associated lift pump but I have no explanation to offer for the lift pump drinking the injector pump lube oil and returning it to the fuel filter.
Pete.

I agree it does strain credulity & I've never heard of it but it was the only point I could think of that engine oil could get in the fuel. The pathway is thru the diaphragm if crankcase pressure is higher than lift pump pressure.
You can see I'm grasping at straws tho. lol

[hpeer]

The simpler explanation for failure is human intervention.

And there the possibilities are endless.

Thinking of some of my own contributions which shall go without description. How many times have we heard of diesel in a water tank or visa versa?

My suggested path forward would be to flush out all the dirty fuel and then monitor the situation. If it is an engine problem it will come back soon enough.

[swordds]

My sincere thanks to all contributors! I agree with possibly grasping at straws but: 1) The gunk in the secondary fuel filter certainly looked, felt and smelled (to me admittedly) like crankcase oil, and the contamination in the secondary filter housing was much darker and more viscous than anywhere else in the system causing me to think this might be the initial source of the contamination. 2) The oil level in the crankcase went from being about 1/4” above the high fill mark to being about 1/4” below the high fill mark after about two hours of run time (I invented in my mind the 1/4 quart of oil, I have absolutely no idea of the quantity this amounts to). 3) Desperate for any solution this seems the most likely juncture for crankcase oil to enter the system (Skipperpete’s photo is exactly correct -thanks). 4) At this early phase of troubleshooting ordering and installing a new lift pump seemed like it would be reasonably cheap and quick. It is still reasonably cheap (though not quick) and may yet be easier than properly disposing of more contaminated diesel.
At this later stage of troubleshooting I agree, perhaps the fuel just “became contaminated” or perhaps the contamination is just a diesel bio-bug and the crankcase oil theory is just a red herring. Simply running the engine with clean fuel might show there is no problem and I am very tempted to do that. But the commitment to buy a new pump has been made and the pump is in the mail and the only hindrance to the original troubleshooting plan is impatience.
When the new pump arrives if I cannot install it because of limited access my next step will be to just add new fuel and run the engine and I will check the crankcase pressure then. I could, and may, jump ahead and run the engine with clean fuel before changing the pump, but the downside might be another set of dirty filters and another couple gallons of contaminated fuel to dispose of.

[hpeer]

jump ahead and run the engine with clean fuel before changing the pump, but the downside might be another set of dirty filters and another couple gallons of contaminated fuel to dispose of.

This is a minor inconvenience.

And it is something you do to salv your impatience while the pump ships.

The pump you can return or sell or call “spares” as many of us do.

[skipperpete]

Hey Sworrds, don’t be too concerned if you did mistake engine oil contamination in your fuel with just plain ol dirty filters.
I took these off a Cat 3406 that was having power surges..... all filters on both engines were sludged up

[hpeer]

Yup, been there, done that.

Installed a day tank, double filter AND carry a bunch of spare filters.

[Compass790]

Actually swordds your statement that the secondary filter housing was the most contaminated/viscous makes it a lot more likely that it is engine oil coming back to that engine mounted filter thru the return line.
Next question is: Is there a return line going from that engine mounted fuel filter fitting that skipperpete circled back to the fuel tank? If so there is your possible tank contamination.
No argument that tank contamination from stuff that is in there is the most likely route as Wottie originally said but given your secondary filter possible oil contamination description it doesnt sound like it.



I've never had the sense that there is engine oil in it when changing a sludgy filter like skipperpete shows so something must have given you the clue that it was engine oil.


I still think you should feed the lift pump with clean fuel & check that its clean or not coming out of return line & that will answer the question.


Following with bated breath