Marine Heavy Fuel Oil Impurities and the Effects They Can Cause to Yanmar Diesel Engines

Blog | June 19th, 2019

Beautifully engineered diesel engines don’t react well when they sip on contaminated fuel sources. Sure, if the marine engine in question is a Yanmar model, it’ll probably keep right on operating, with its powerful engine stroke delivering abundant quantities of propulsion thrust, but at what cost? What kind of damage takes place inside a high-performance marine diesel engine when it’s forced to drink heavy fuel oil impurities?

All About Heavy Fuel Oil

Often shortened to HFO, this liquid medium is used to provide thrust for large commercial vessels. If a massive freighter is transporting cargo across the globe, there’s a good chance its engine combustion chamber is burning an HFO. Heavy in aromatics and burnable hydrocarbons, these high viscosity fuels contain long-chain polycyclic hydrocarbons. That’s something of a problem, especially since the fuel has to be pumped and combusted. Added to large marine vessel engines, special preheat chambers make sure the thick, treacly substance reaches a required state of fluid solubility. That’s all well and good, but now we’re left wondering about the damage this long-chained disarray can do to a Yanmar Diesel Engine.

The Effects of Sulphur and Silicate Contaminants

All HFO fuels contain sulphur. Actually, ULSFO (Ultra-Low Sulphur Fuel Oils) have knocked the content of this noxious element down to less than 1.0%. Below 0.1%, Marine Gas Oil uses distillate technology to almost entirely eliminate this fuel contaminant, but that’s a story for another article. With higher sulphur blends, the sulphur exits a ship engine as sulphur oxide, which is a nasty environmental contaminant. Carbon residue is another issue, which presents as a thrust attenuation problem back at the engine. Coated in soot, diesel engines age rapidly, unless they’re maintained regularly. Aluminium particles are in evidence, too, right inside the injector assembly. Bonding with silicon to create grains of engine-damaging aluminium Silicate, if the mandate-established 60 mg/kg limit is surpassed, catalytic fines may be attributed to the owners of an offending vessel.

Even water leaks can make their way into heavy fuel oil feed lines. When this happens, engine efficiency drops. Ship thrust comes next, for the water hinders the fuel-oil combustion cycle. Worse than this, however, the water will change state when it burns. Caught up in a Yanmar Marine Diesel Engine’s combustion chamber, that steamy mix soon goes to work on the engine components. Corrosion takes place, parts lifespans decrease, and heat transfer ratios plummet. Last of all, after weighing the effects of water and sulphur; let’s talk about heavy fuel ash. Present as a 0.2% blend component, heavier metals, including vanadium and nickel, are suspended in HFO liquids. Ash modifiers are used to keep this ratio low.

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