An uncontrolled overspeed event in a diesel engine caused by an external hydrocarbon source entering the intake manifold. Because diesel engines control speed by fuel delivery rather than air throttling, ingesting crankcase oil from a blown turbo seal or combustible gases in the atmosphere will cause the engine to accelerate until it destroys itself mechanically or seizes from lack of lubrication.
Heard on the job
Grab a clipboard and block the intake before that runaway diesel throws a rod through the block.
Insider tip
The only way to stop a runaway is to cut off its air supply completely; turning off the ignition key does nothing because the engine is running on its own oil.
Also heard as
- diesel runaway