John Deere engines will also operate on lower viscosity fuels. However, with rotary pumps, as fuel viscosity decreases, fuel flow to the engine decreases resulting in lower power. Engine response, load recovery, and starting time are adversely affected. The reduced lubricating properties of lower viscosity fuels may also reduce pump life unless special internal parts are used.
Engines which use in-line pumps are also sensitive to lower viscosity fuels, resulting in reduced power. In-line pump components are not as sensitive to wear as rotary pump components since in-line parts are lubricated by engine oil.
Engine operation using extremely low viscosity fuels such as JP-4 and Jet B is not recommended. Significant fuel injection equipment wear results from use of fuels with viscosities below 2.0 centistokes. If JP-4 is used, viscosity must be raised by adding 10%-20% new lube oil by volume and 0.2%-1% cetane improver such as hexyl nitrate. Even with these additives to raise viscosity and cetane number, a performance loss should be expected.
The use of high specific gravity fuels (lower API) could result in power levels exceeding the engines approved power rating. Operation above the approved engine power level will result in reduced engine life and increased operating costs.
In general, ‘light’ fuels may give poor low-load / highspeed
performance, poor injection system lubrication, lower power, and poorer startability. ‘Heavy’ fuels may cause fuel filter plugging at low temperature, poor starting, additional combustion zone deposits and higher wear due to higher sulfur levels. Pretreatment of ‘heavy’ fuels may be required, such as prefiltering, water separation, and heating. Contact Sales Engineering if use of other than recommended fuels is anticipated. The following tables summarize various fuels, comments concerning modifications required to maintain pump and engine life, and performance effects that may be encountered.
