I’m getting what seems like lube oil in my day tanks. I can’t figure where it’s coming from. 12-645 EMD turbo for mains and John Deere 6068TFM50 northern lights generators. Any ideas would be much appreciated.
What/where specifically are you observing that leads you to believe there is oil in the fuel day tank?
I’d think any oil getting to that tank would be via fuel return lines from the engine. Is there any way to sample off that flow to verify? And if so to isolate by bank?
It’s been a while since I was on ship with EMDs, but these are unit injectors correct? Are the injectors oil cooled? What is that sealing interface at the injectors? Don’t suppose you have a fuel system and oil system diagram handy do you?
There is quite a bit of fuel in the centrifuge and it just recirculates the day tank fuel. And the the fuel is very dark when priming racor housing during filter change.
It has to be coming through the return lines. I was thinking it mite be bad injector seals but that should create positive pressure and leak fuel into the oil.
Yeah I will grant it doesn’t make much sense, usually you see fuel-in-oil contamination vs oil-in-fuel.
Have you had a sample of that “dark” fuel sent off for testing? Dark fuel could be run of the mill fuel contamination, microbial growth.
Also, is there an engine gear driven low pressure fuel pump on these?
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Other than looking like lube oil what makes you think there is cross contamination? Maybe someone is dumping old lube in the fuel to get rid of it? Try a blotter test on a coffee filter or paper towel.
Number of options.
1.Go through your logs to see if any engine is using any more oil than previous months. If lube oil consumption is consistent then it’s not the engine.
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SAFELY try to divert the fuel return from an engine into a drum. Then do the same to another, same model engine. If the return fuel looks the same then it probably not coming from an engine.
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Walk around your vessel & check the sounding plugs & screw-on vents if they are under 2" to see if they’ve been tampered with. I worked on a well stimulation vessel once & the client was pouring dirty oil/sludge into a fuel tank because they thought that fuel tank was isolated for their use only to pump down the well. People do stupid things, try to rule out stupid people cause.
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Do you have dirty or heavy oil tanks above your F/O tank?
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Order some engine oil dye & put it into the engine that uses the most oil. I’ve used that stuff a lot over the years, always in fuel looking for dilution but it can be put into motor oil too. Dye is cheap & the UV detection glasses are even cheaper. I have my own (Tao Tronics) which I bought for $12 from Amazon for my rental property business. If you order the glasses & UV light from Caterpillar they’ll send you the same exact brand as my $12 Amazon but they will charge you $300+. If you have reservation about putting UV dye in your engine, do it 24hr before a service is due since you’re going to dump the oil & change filters anyways.
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It’s probably bugs. You can’t kill them or get rid of them without cleaning the tank but a biocide will sterilize them so they cannot reproduce.
You would have to empty the tank and clean it.
You can do a slide test for bugs and if that gives you a hard yes then you can plan for it.
If it is bugs and you let it go it can really do some damage to whatever is drawing from that tank. I’ve seen an EMD suck pure water from a day tank. Raycor globes were completely full of water. 100% clear and we just primed the engine and the injectors didn’t skip a beat. I’ve seen bugs shut the engine down.
I’ve also had to muck out a tank that had 4” of black slime (dead bugs) in it.
Do yourself a favor and get the slides and an incubator.
If your company won’t spring for the test slides and incubator, you can send a fuel sample to DNV and they can test it. Just do some research on what microbes will do to the equipment and draft a letter to your Port Engineer and drop it in his/her lap. Sometimes you can only give them information and options. The rest is up to them.
Let us know what you find.
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bugs would be the last thing i’d want to see but you better check that. I 2nd the motion to see if anyone is pouring oil or something into the day tank, and i’ve had adjacent tanks leak into one another as well. I’ve been aboard ships where mixing old crank oil into the fuel was done but a bit harder on the purifiers. (and operators) but NOT AS BAD AS ANCIENT BUGGED UP FUEL!! I’d be eyeing the injector theory unless you’re into some real old fo tank.