Modern-Day Diesel

January 6, 2012 06:31 PM
 
Modern Day Diesel

A new breed of diesel affects fuel storage and handling

New diesel fuel injection systems that have been used on Tier 3 diesel engines since 2006 have added challenges to on-farm fuel storage, fuel handling and even fuel filter changes.

Depending on the manufacturer and technology, a modern diesel engine might use a computerized diesel fuel injection system, a variable-vane turbocharger, multiple turbochargers, an exhaust gas recovery system, a catalytic converter or a special exhaust system filter. The following facts, myths and tidbits will help you update your on-farm fuel program to satisfy the needs of the new breed of diesel engines:
 

  • All diesel fuel sold for off-road use in the U.S. as of June 2010 is ultra-low-sulfur diesel (ULSD) fuel. Sulfur is a natural component of crude oil. Your grandpa’s traditional No. 2 diesel fuel contained 1,000 to 2,000 parts per million (ppm) of sulfur. The low-sulfur diesel (LSD) required by Tier 3 engines has no more than 500 ppm sulfur. ULSD used in Tier 4 engines can have no more than 15 ppm of sulfur.
     
  • ULSD fuel is safe to use in older diesel engines, but leftover traditional high-sulfur diesel fuel can cause significant fuel injection system damage to Tier 3 and newer engines.
     
  • The processes used by refineries to remove excess sulfur from fuel coincidentally also remove lubricating components from the fuel. As a consequence, raw ULSD fuel does not have the lubricity of traditional diesel fuel. Refineries must add lubricating agents to ULSD fuels to regain lubricity. Many engine manufacturers recommend adding additional fuel conditioners to on-farm storage tanks to further improve lubrication of engine fuel injection systems.
     
  • The old over-the-road trucker’s trick of adding automatic transmission fluid, engine oil or other lubricants to diesel fuel to clean and lubricate injection systems is harmful to Tier 3 and Tier 4 injection systems. Automatic transmission fluid and other lubricants contain zinc, calcium and other compounds that form deposits in high-pressure electronic fuel injectors. Those additives also form deposits when combusted, which clogs injector tips and exhaust system components.
     
  • Tolerances in modern diesel fuel injection systems are incredibly precise. "If you take an [electronically controlled] injector, pull out the plunger and hold it in your hand for a minute, your body heat will expand the plunger enough so it won’t fit back into the barrel," says Roger Meanor, a certified Caterpillar instructor. "There’s absolutely no room for any sort of contamination in electronic injectors."
     
  • Electronic fuel injectors are lubricated by the diesel fuel that flows through them. Even microscopic drops of water interrupt the lubricating film of fuel and can cause catastrophic injector failure.
     
  • Water filter/separators used on newer engines use special polymers to absorb water out of fuel. As they absorb water, the polymer filter elements swell, and can eventually restrict fuel flow and degrade engine performance.
     
  • Tier 3 and newer engines require their electronic injector fuel to be filtered to 2 microns. Fuel delivered to farms is generally filtered only to 10 microns. Tier 3 engine filters are designed to filter 10-micron fuel down to 2 microns but might require frequent changes if farm storage tanks are contaminated with rust, sludge or bacteria. "We can install 2-micron [discharge] filters on customers’ tanks, but they’re special filters and you may have to change them more often," says Ron Mitchell, plant manager for Diamond Oil Company in Perry, Iowa.
     
  • It is a myth that "dirty" filters clean better than new filters. That theory was based on fine-mesh metal screens. Modern diesel fuel filters are far more sophisticated than older screen-type filters. Modern diesel fuel filters are often pressurized at more than 100 psi. Excess contamination in dirty filters can be forced under pressure through the filtering element and into sensitive injection systems.
     
  • Engine manufacturers now discourage prefilling new engine fuel filters with diesel during a filter change—unless the new filters come with a special filter-filling funnel that directs fuel only to the intake side of the filter element.
     
  • How much fuel contamination is too much? Case studies show road dust that accumulates inside the hose nozzle on a portable fuel tank in the back of a pickup can introduce enough contamination to a combine’s fuel system during a long harvest to eventually impact engine performance.

 

Fixes for Frigid Fuel

No matter where you live, if temperatures fall below 30°F, there is a risk of diesel fuel in farm equipment "gelling." Refineries switch to winter-grade diesel, which helps. But if you want to be certain diesel engines will run no matter how cold it gets, here are some things to consider:

 

  • Winter-grade No. 2 diesel has a cloud point (where it begins to gel—around 15°F. No. 1 diesel fuel has a cloud point around –50°F. Blending No. 1 fuel with No. 2 fuel proportionately lowers the cloud point.
     
  • Over-the-counter anti-gel additives can lower the cloud point of No. 2 diesel fuel below 0°F if blended at recommended rates. When protecting large tanks of fuel, it’s often cheaper to use an additive than a high proportion of No. 1 diesel fuel.
     
  • There are products advertised to un-gel diesel fuel. Sources say there is no testing standard for such products and therefore no scientific way to compare results.
     
  • An old tactic to prevent gelling is to "thin" diesel fuel with gasoline or kerosene. But Randy Thompson of Phillips Petroleum says, "Research shows that less than 0.5% gasoline in a gasoline/diesel blend can cause pre-ignition problems. As little as ½ gal. of gasoline in 100 gal. of diesel fuel could cause enough pre-ignition to damage an engine."
     
  • If you need to limp a gelled engine to a shed, fill a 5-gal. fuel can with room temperature No. 1 diesel or winter-grade No. 2 treated with anti-gel additive. Rig a suction hose from the can to the engine’s fuel filter. Change the filter, prefill the new filter with No. 1 fuel and hand-prime the fuel pump. In the shed, "thaw" the rest of the fuel in the tank.
     
  • Biodiesel fuel might have a higher cloud point than petroleum-based diesel fuel, and anti-gel additives might or might not interact with biodiesel fuel to prevent gelling.

 

Read more fixes for frigid fuel.

Read Dan Anderson's "In the Shop" blog.

See more shop tips and tricks.


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