How to Detect a Diesel Fuel Leak

Updated February 21, 2017

You can test for diesel leaks at home, and do not need to spend the time and money required to bring your vehicle to a local shop. By adding a basic detection dye to your fuel tank, you can perform a quick diagnostic test in order to decide if your vehicle will need further maintenance to repair a leak. You can purchase the detection dye from places like Surf-Prep, a dealer in Kentucky. The price of the dye ranges from £14-$96 and contains enough dye to treat 1,000 gallons of fuel.

Pour leak detection dye into the fuel tank of the vehicle that you're testing, adding one ounce of dye for every 10 gallons of diesel fuel.

Let the engine run for two to three minutes so that the dye will be distributed throughout the fuel system.

Turn off the engine.

Check for leaks in every area of the engine using a black light. If there is a leak, the detection dye will glow green or pink under the light (depending on the brand of dye used). If you do detect a leak, bring the vehicle to your local repair shop immediately. This is not something that you can fix yourself.


Do not spill and leak detection dye on the engine, which may result in a false positive.


Diesel fuel, like all fuels, can cause a serious safety risk when there is a leak from an engine. Just a small leak can lead to a fire or an explosion. Make sure that you are working in an area where there are no flames present and the engine is off while you are looking for leaks.

Things You'll Need

  • Fuel leak trace dye
  • Ultraviolet light (black light)
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About the Author

Joshua Black is a business writer, copywriter and blogger who began his professional writing career in 2000. He has written numerous eBooks and has articles published on various websites and ezines on topics in small business, marketing, sales and sports. He holds a Bachelor of Science in industrial design from Western Michigan University.