The danger of diesel and water

Diesel and water, not a good mix


By Direction Plus
With the increasing popularity of the diesel fuelled vehicles, which boasts better efficiency, more power and reduced emissions, there also comes with it, a fair share of problems such as engine rattles, injector sticking and stalling problems.


With ultrafine tolerances of diesel pumps and injectors, the diesel fuel system is highly susceptible to fuel contamination. Any contamination of water in diesel fuel can be disastrous to both the injectors and the fuel pump, causing expensive injector and fuel pump failures, the two big-dollar components in any diesel fuel system.


Diesel fuel system injectors are required to inject diesel into the cylinder to precisely inject the required amount of fuel. A delay in fuel injection caused by wear (from contamination) or poor fuel lubricity commonly results in incorrect fuel delivery, resulting in reduced performance and poor fuel economy.


Water can occur in your diesel fuel system in many ways, here a few examples:

  • A common one is River crossings, water enters into the system via the fuel tank breather.
  • Leaking hoses allowing air to be sucked in
  • Fuel stations that don’t have a high turnover of fuel
  • Drivers that tend to run vehicles around between half and empty, this creates air space in the tank allowing water to condensate on the walls of the tank
  • Driving through rain and wet roads, water mist being sucked in to tank via the breather



Some ways you can minimise the effects of water contaminating your fuel


While the Fuel Standard (Automotive Diesel) Determination 2001 prohibits the presence of free water in all diesel sold in Australia, there is nothing the law can do to prevent dissolved, or emulsified water in diesel fuel, which in time, settles out of the fuel and collects at the bottom of the fuel tank, to initiate and spread corrosion throughout the entire fuel system.

Now, more important than ever, is the best time to ensure that the fuel entering your diesel engine is highly refined and scrupulously clean. There are a couple of ways to make sure you get the most out of your common rail engine:


  1. Where possible, fill up at a reputable fuel station
  2. Never use biodiesel or biodiesel blended fuels
  3. Always use OEM or OEM quality fuel filters and replace them at the specified service intervals
  4. Try not to fill from drums, if you have to, ensure that they are contaminate free


Following these few steps is cheap insurance against expensive failures and repairs.


There are other ways of adding an extra line of defence, such as a Direction-Plus™ Diesel Pre-Filter Kit. These kits are installed between the fuel tank and the OEM fuel filter. The Direction-Plus™ kits do all the hard work by removing the majority of contaminants and water from the fuel, leaving your factory filter to remove the finer contaminates left. This will ensure that your common rail diesel gets the cleanest fuel possible.


Benefits of fitting a Direction-Plus Pre-Filter kit:

  • First line of defence for your diesel fuel injection system
  • Reduce wear and tear and avoid repair costs that can exceed $10,000
  • 95% water separation and superior particle removal
  • Ability to separate emulsified water from ULSD
  • Clear water drainage bowl or audible alarm along with a warning light will help to easily identify removed water or water contaminated fuel
  • No filter bypass – contaminated fuel will not be sent to the fuel system even when the filter is blocked


Another way to help with emulsified water in diesel fuel is by using a fuel conditioner. Conditioners such as the Direction-Plus™ Diesel Fuel Conditioner help by:


  • Increasing power, engine efficiency, and vehicle drivability by way of a 4 point cetane boost
  • Preventing lower temperature range fuel flow problems at cold start (-1°C)
  • Containing operator safe, non organo-cyanide based biocide to treat diesel bug
  • Being suitable for older and newer diesel fuel systems
  • Being suitable for low sulphur fuel and fuel with moisture present
  • Minimising engine wear & tear with the lubricity agent
  • Containing de-polarising agents and high-performance corrosion inhibitor
  • Dissipating moisture to reduce risk of injector tip damage
  • Product treat rate is 1part DFC : 500 parts diesel fuel (1L treats 500L fuel)
  • Use regularly for best results – residual effect offered over a typical treatment interval of 5000km



How do you know if there is water in your fuel system?


Here is a list of some symptoms you may experience if your diesel fuel is contaminated with water:


  • A loss of RPM and power
  • Slimy, clogged filters
  • Hazy, cloudy fuel
  • A build up of sludge in the fuel tank
  • Excessive smoke
  • Foul odour
  • Corroded injectors


If you don’t have much knowledge of cars, the loss of power and RPM will probably be one of the first things you notice. Checking your fuel should be the next thing on your list; if it is hazy or cloudy your diesel fuel is most definitely or likely contaminated with water.


What should you do if you have suspicion of water in your fuel?


Do not start the vehicle, if possible drain the tank and fill with fresh fuel and bleed the fuel system, if you are confident that all the water has been removed start the vehicle and continue on your way.  If this is not possible, or you are still concerned, have an experienced diesel pump room specialist look at the vehicles fuel system for confirmation.


Visit your local TJM store to view the range of Dometic products and find your perfect cooler.