You might have heard of some diesel truck or pickup truck whose engine "ran" and only stopped when the diesel was gone. It can be no exaggeration, no mechanic story (the gearhead version of fisherman's story, you realize ...). That kind of thing comes about. The engine starts to accelerate abruptly and doesn't quit anymore. Once a Detroit Diesel engine currently being turned on just after 30 years stopped.
Scary, is not really it? It is actually as if it have been a monster that awakens furiously from its sleep, prepared to destroy individuals who dared to bother him.
The gasoline engine makes use of a throttle managed throttle valve to manage the volume of air and therefore the volume of fuel to regulate the engine velocity. In diesel engines the principle is somewhat various: there isn't any butterfly valve, plus the engine pace is controlled from the variation of fuel injected to the cylinders. The diesel engine accelerator acts on an injection pump that regulates the volume of diesel to get sent on the engine.
Diesel won't use spark plugs for combustion - its ignition is by injecting the fuel into the compressed air and heating the cylinders. Hence, when the diesel begins to get injected to the cylinders without the need of pressure or volume regulation, the engine can accelerate uncontrollably. This involuntary and uncontrolled acceleration is named "diesel runaway", also called "engine fired" in Brazil. But how does this come about? In many different ways, as we shall see under. For more data pay a visit to mecanica diesel
From the first situation, in far more worn engines, the place there is clearance between the pistons and the cylinder walls, the combustion gases can pass by the sides with the pistons and in to the crankcase and carry oil mist in to the inlet. Since the lubricating oil has combustion properties similar to that of diesel, the engine accelerates with this particular extra fuel injection. The higher the engine velocity, the higher the volume of oil mist forced by the crankcase breather, causing an engine power cycle that could lead to the total consumption in the lubricating oil and consequent breakage - typically an explosion like this:
This cyclic lubricating oil feed also can happen should you put too much lubricating oil in the engine - that's why the manuals are emphatic: never ever include a lot more oil than encouraged. This is because in lieu of steam or mist of oil, who can climb via the breather may be the lubricating oil itself, which can cause precisely the same "firing" on the engine.
Probably the most frequent circumstance, on the other hand, is what we see within the video above: a failure or misadjustment of your injection pump or even the accelerator. In the video situation, the guy was apparently adjusting the injection pump level when some thing went incorrect plus the fuel flow was no longer controlled from the component, feeding the engine as if the throttle was fully depressed. Increasing the engine velocity triggers the oil to begin to rise through the vents, trying to keep the engine operating as in other cases. For extra details stop by curso de mecanica automotiva
When realizing that his Detroit Diesel fired, the guy takes a brave as dangerous attitude. He picks up a piece of rubber or tarp and tries to manage the only issue that may be inside attain: the intake of engine air, leading to the machine to drown. During the approach he could have misplaced his fingers, but the good news is he just broke the blades with the turbine.
Should you be questioning why he did not get into the cockpit and turned off the engine, that is why diesel engines, as we've said prior to, have no spark to ignite. The engine is shut down by the fuel shut-off. Because the component responsible for cutting the fuel had broken in his hand, the sole answer was to drown the engine. Even so the method is risky: the engine can literally explode depending within the speed and amount of fuel, and you also do not have to utilize your imagination to understand what comes about when an engine filled with oil and scorching iron explodes.
Today, with electronically managed diesel engines this is often harder to come by, specially considering that modern engines have security systems for closing the consumption, which causes engine drowning. This also demonstrates the importance of doing the correct maintenance procedures and checking the issue from the components just before trying to commission them.