The Blob from the Tractor Fuel Tank

By Tommy Brannon, certified ASE Master Auto Technician

Just when you thought it was only a figment of the imagination, the Blob comes alive again – this time morphing to life in the tractor fuel tank. It’ll suck the life out of your tractor!

While astronomers were trying to uncover the secret of a mysterious glowing Blob in outer space, another, more sinister Blob was invading the fuel tanks of diesel tractors here on Planet Earth. The outer space Blob was first spotted in the late 1990s by astronomer Chuck Steidel at Caltech. But the original Blob was the “star” of a 1958 self-titled B-horror movie.
Opening Scene: You are bush hogging your back pasture when you notice a hiccup and loss of power especially going uphill. Things don’t feel quite right. (cue cheesy horror movie music) You back off the throttle and the tractor idles OK. You continue mowing and the loss of power returns. Look out!  You may be experiencing an attack by The Blob from The Tractor Fuel Tank.

Everyone has heard the term “oil and water don’t mix.” This is not just an idiom to describe why you are having trouble communicating with your horse or trainer. They really don’t mix! Diesel fuel is a light oil; in fact, it is the same as home heating oil except that the two have different additives for different purposes. Just as water condensation occurs on the windshield of your truck or the grass in your pasture, it also occurs in the fuel tank of your tractor. That is why there is a water separator on the fuel filter. You should drain it every time you put fuel in your tractor.  

Water is heavier than oil and it will accumulate at the bottom of the filter. Unfortunately, over time, it will also accumulate in the bottom of the tank, thus making the blob. Most fuel tanks are designed with a depression or channel on the bottom, lower than the fuel pick up, so that water will not be sucked into the fuel system.

Some tractors have metal tanks and some have plastic ones. As the water is at the bottom of the tank not exposed to air, there is little chance of oxidation that could rust the bottom of a metal fuel tank; the sides of the tank, however, are a different story. It is a good idea to keep the tank full when the tractor is stored so that the sides of the mettle tank won’t rust.  

In spite of regular draining of the water out of the water separator, eventually the tank may have to be drained and flushed to get rid of “The Blob.” Any dust or chaff that falls into the fuel tank will settle and blend with the water to make “The Blob.” The Blob is so viscous that often it can be removed with a bent wire or grabber. After cleaning out the tank, it is a good idea to add a diesel fuel cleaner additive, such as Stanadyne or Seafoam to the fuel system. 

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