Skip to main content

Ask SAIL: A Diesel Conundrum

 I’m trying to determine why the diesel fuel for my 4.108 low-line Perkins is getting black. I use the word “black” instead of dirty, because the fuel looks as if it is getting crankcase oil (or soot) mixed in it.

A Diesel Conundrum

Q: I’m trying to determine why the diesel fuel for my 4.108 low-line Perkins is getting black. I use the word “black” instead of dirty, because the fuel looks as if it is getting crankcase oil (or soot) mixed in it. I’ve taken a sample of the fuel and let it sit for several months, but whatever is suspended in it doesn’t settle to the bottom. This is not the typical algae sludge that grows in fuel when water gets in the tank, and it gradually occurs even after I drain all the fuel out and refill the tank. The engine runs great. The fuel color doesn’t seem to have any negative impact, other than bugging me. Here is what I’ve done:

Replaced the aluminum fuel tank—despite being refilled with brand-new fuel, it started getting dirty right away, I believe from running the engine

Replaced the fuel lines (when the tank was replaced)

Bypassed the mechanical fuel pump and installed a marine grade electric pump. The fuel lines no longer run through the mechanical pump, hence there is no opening there to the crankcase

The engine has a primary Racor fuel/water separator and a secondary filter. I replace filters yearly and they are always clean

Replaced all injectors and the high-pressure pump

Is it possible for crankcase oil (or blow-by soot) to get into the fuel and be returned to the fuel tank? I’ve traced the lines and do not see where or how this could occur. If what I’m seeing isn’t oil, do you have any ideas what it might be?

Jim Brady, via sailmail@sailmagazine.com

NIGEL CALDER REPLIES

I confess this not only is a new one on me, but I’m at a bit of a loss. The only place I can see any possible interaction between the fuel and the engine oil or carbon in the engine is at the injectors, where excess diesel is recycled back to the fuel tank (through the injector bleed-off lines). Even so, I can’t think of an explanation for this. Perhaps one of our readers has a better idea?

Ed note: If anyone has the answer to this mystery, please let us know by e-mailing it to acort@sailmagazine.com

Got a question for our experts? Send it to sailmail@sailmagazine.com

Related

LEAD-Celeste-in-the-Tuamotu

A Watermaker Upgrade

As a classic-boat sailor, I’ve long held that simpler is the better. I still think this is true: a simpler boat is cheaper, she has less gadgets to break down and there’s a certain satisfaction in knowing you’re able to handle a bit of discomfort. Thus, for a long time, I sailed ...read more

01-LEAD-IDECsport_180919_032

Sailing Speed Records

Although the 1903 defender of the America’s Cup, Reliance, was deemed a “racing freak”—the boat pushed design rules to their limit and couldn’t be beaten, at least in very specific conditions—designer Nat Herreshoff was nonetheless onto something. A century later, purpose-built ...read more

BVIFeetup

Chartering with Non-sailors

Three tips on managing the madness First-time charterers and first-time sailors aren’t at all the same thing. One group may struggle with beginner chartering issues, like sailing a multihull, catching a mooring or dealing with base personnel. For the other group, though, ...read more

AdobeStock_455372159

A Gulf Stream Crossing at Night

Even the dome of light glowing above the city behind us had disappeared as if swallowed in a gulp by Noah’s whale. The moon was absent. Not a star twinkled overhead. The night was so dark we could have been floating in a pot of black ink. The only artificial lights to be seen ...read more

00-Lead-549215sJL2uLEa

Summer Sailing Programs

Every year, countless parents find themselves navigating the do’s and don’ts of enrolling their children in a summer learn-to-sail program for the first time. While the prospect of getting your kid on the water is exciting, as a sailing camp program director, there are a lot of ...read more

ntm

Notice to Mariners: U.S.A! U.S.A! (Well, sorta…)

Some thoughts on a couple of recent developments on the U.S. racing scene that are more than a little at odds. To start with, congratulations to the US Sailing Team (USST) and its outstanding showing at the 53rd French Olympic Week regatta in Hyeres, France, with not one but ...read more

01-LEAD-11-Katrina-Zoe-Norbom-850_9438

The 52 Super Series

The 52 Super Series is widely considered one of the top circuits in the world for monohulls, and in this era of rapid change, the TP52—or TransPacific 52—has managed to stay the series’ boat of choice for 10 years. Not only that, but as the class marks its 20th anniversary the ...read more

MHS_summer-2048x

Podcast: New Issue Preview Multihull Sailor Summer

In this episode of Point of SAIL, Principal Editor Adam Cort and Managing Editor Lydia Mullan talk about the Multihull Sailor summer issue, their favorite articles, and offer a behind the scenes look at SAIL. May 2022 ...read more