Why Petrol Destroys a Diesel Engine
To really get your head around why petrol is so catastrophic for a diesel engine, you need to understand that diesel fuel does more than just burn. It’s not just about making the car go; it’s about keeping the engine's delicate mechanics happy. A key property of diesel is its oiliness, and modern diesel engines are designed to rely completely on this quality to survive.
This inherent oiliness is the lifeblood for the high-pressure fuel pump, a true masterpiece of engineering that works under incredible stress. Think of this pump as the heart of your fuel system. It’s built with components machined to tiny fractions of a millimetre, and it needs a constant supply of lubricant to keep going. That lubrication comes directly from the diesel fuel itself.
As the pump tears itself apart, it creates tiny metal filings called swarf. These microscopic shards are then pumped at high pressure through the rest of the fuel system. They act like liquid sandpaper, scouring the fuel injectors and contaminating the fuel lines, filter, and potentially even the engine itself.
When you introduce petrol into this high-compression chamber, it doesn’t wait for the right moment. It ignites far too early and uncontrollably, creating a violent explosion rather than a controlled burn. This is known as detonation or engine 'knocking'.
