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Turbocharged diesel engines produce an immense amount of torque. That torque makes them great for towing, which is why they are so often used in pulls and heavy hauling. However, whether you have a TDI Volkswagen or a Ford SuperDuty Turbodiesel, turbo diesel runaway is something you need to know about. It can catastrophically destroy a diesel engine, and can be dangerous or even deadly.

What causes diesel runaway?

There are several factors that can contribute to turbo runaway in a diesel, and many of them can be prevented with routine maintenance.

One of the biggest contributors to turbo diesel runaway is a leaking turbocharger or turbo seal. When this happens, engine oil gets past the turbo and enters the combustion chamber in an uncontrolled manner. As such, the driver is no longer in control of how much fuel goes into the engine, as it is now burning the leaking oil.

Another cause of diesel runaway is a leaking fuel injector. Much like a turbocharger leak, a leaking diesel fuel injector allows oil to slip past the injector seals. In a similar way, the engine can now burn the engine oil instead of just diesel fuel. Unfortunately, there is no way to shut it down.

This means that the engine can’t be shut off by simply turning off the key, since it is now burning a fuel that is not controlled by the fuel pump system. It will continue to run, spinning ever faster until it catastrophically fails.

Can you stop a diesel turbo runaway?

Volkswagen TDI diesel Engine
VW Diesel Engine | Volkswagen

Unfortunately, there aren’t many ways to effectively stop a turbo diesel runaway. If your vehicle has a manual transmission, you can slam into gear and try to stall the engine mechanically. This, of course, will likely ruin the transmission, but it can be less dangerous than letting the engine blow itself to pieces.

Another way is to cut off air going to the combustion chamber. Only do this if you have easy access to the intake hose. Of course, you don’t want to be anywhere near the engine when it spins out of control. But if you have an aftermarket intake with open access to the air hose, you can try to block the airflow and choke the engine.

Finally, many modern turbos have an anti-shudder valve, or ASV. This is an electronically-controlled flap that opens when the key is turned on. As such, it automatically shuts off when the key is turned off. If your vehicle has an ASV, simply turning the key off will close it. This will choke the engine and stop the diesel turbo runaway.

Regular maintenance can prevent engine failure

Like any vehicle malfunction, not all turbo runaway conditions are preventable. Sometimes, bad components or freak incidents can cause a runaway, even on a well-kept engine.

However, keeping up with oil changes and diesel fuel additives can help keep your turbo and fuel systems in better condition. By maintaining proper lubrication for your injectors, turbos, and internal engine parts, you can prevent the types of diesel runaways like those described by CarThrottle.

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