⚙️ Causes of Diesel Runaway Here are the most common causes: 1. Turbocharger oil seal failure • The turbo’s oil seals leak, letting engine oil enter the intake. • The engine starts burning this oil like fuel. • Common in older or high-mileage turbo diesels. 2. Excessive crankcase pressure (blow-by) • Worn piston rings or valve seals allow oil mist and vapors into the intake through the breather system. 3. Overfilled engine oil • Too much oil causes it to foam and enter the intake via the breathe