Diesel Fuel Contamination Symptoms

Diesel Fuel Contamination Symptoms

Last updated:

By Shane Garcia

Most people are probably concerned about the cleanliness of diesel fuel but are unaware of the symptoms of diesel fuel contamination. Diesel fuel is often used as an alternative fuel to gasoline, and its pumped into the fuel tank of almost every vehicle on the road. However, diesel fuel is not just another fuel; it’s a complex mixture of hydrocarbons, and it’s important that the fuel you’re using is safe to use in your vehicle.

The fuel you pump into your car goes bad over time. When diesel fuel goes bad, it can cause serious problems. The fuel can cause engine damage, and it can even cause fires if it comes into contact with certain materials, such as vinyl.

Check out the diesel fuel contamination symptoms to keep your vehicle running smoothly.

1. Replacing filters regularly

Filters are meant to catch and hold water; therefore, if you find water in your fuel, that means you need to replace your filter. The most common symptom that you are likely to notice if your fuel is contaminated is your filter getting fuel faster than it normally does. However, other issues might also cause blockage in your filters, like having sludge in them.

  • A sludge, also referred to as a diesel bug, is a brown or black bacteria commonly found in the area between the water and fuel. It grows over time if left unattended and becomes difficult to break up. It’s usually a sign that your contamination has reached a dangerous level. Always remember to look for traces of diesel bugs every time you go to change your filter.

2. Fuel appearance

Normal fuel is usually clear and bright. If it starts to appear cloudy, chances are it is contaminated with water. That means it requires treatment to ensure there’s no bacteria growth or buds forming. You can take your fuel to be checked, or you can look at it yourself. Below are some things to look out for to know if your fuel appearance is normal;

  • Water suspension: This type of contamination is what makes diesel fuel cloudy. Suspended water binds with fuel molecules, and as the fuel fills up with water, it becomes cloudy. Once the fuel can’t hold it anymore, it drips in bits from the bottom of the fuel tank.
  • If water emulsifies: Emulsified water occurs when fuel goes through filters and pumps. As the water becomes emulsified, it turns from being cloudy to milky. The process can occur under changes like pressure, agitation, etc.
  • Free water: Free water doesn’t mix with the fuel. It creates another layer of its own that sinks and goes under the fuel, which can lead to the formation of diesel bugs which puts engines and vehicles in danger.

3. Tank Erosion

Corrosion is a mature stage of fuel contamination. It happens if water or sludge is left untreated and they eat away at the tank. You should always check your car engine for signs of rust because if water gets into your diesel fuel tank and is left untreated, it may cause the following problems;

  • Corrosion of the fuel system: Reduced lubrication can cause premature wear and damage. It’s not easy to detect this problem, so you need to be keen and act early.
  • Blocked filters and pumps: Sludge can eventually cause blockages in the pumping system, which end up damaging it. The repairs for this are expensive and can also affect your usage of the machinery.
  • Engine problems: If you have contaminated fuel in your car, you will experience issues like speed changes, loss of power. This is an indicator that the fuel isn’t burning normally or the sludge present is blocking the flow of fuel into your engine.
  • Fuel inefficiency: Water in the fuel can prevent it from burning the way it’s supposed to. Because of this, you’ll end up using more fuel than the intended amount.

Symptoms of contaminated diesel fuel are a serious problem that will always be there. It would help if you handled it as soon as it’s discovered in order to avoid future problems, which usually turn out to be more costly.

Shane Garcia


3 Thames Street BOLTON, BL1 6NN

01204 456413



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