ShockerPASS Support

A diesel engine is considered a ‘runaway diesel’ when the engine’s RPM rises rapidly above rated RPM redline. This typically means that the diesel is running uncontrollably and will not stop until the engine either turns red hot and seizes (causing expensive damage to your engine) or there is some kind of explosion. When a diesel ‘runs away’ the only way to stop it is to shut off the ambient air supply with a positive air shut off valve.

Yes, all diesel engines, no matter how new and powerful, have the capacity to run away if the engine starts taking in fuel from the ambient air.

Diesel engine runaway is caused when the engine ingests unburnt hydrocarbons within the engine air intake supply. This means that rather than burning just the diesel fuel within the tank, the diesel engine starts to take in other fuel sources from the ambient air (such as natural gas, propane, gasoline fumes, etc.). This causes the engine to run faster and faster until the engine seizes and fails or leads to a much more catastrophic explosion.

The only way to stop a diesel engine runaway is by closing off the air supply to the engine. This will remove the engine’s ability to continue taking in air and fuel and stop the engine entirely. The ShockerPASS is a positive air shut off valve, so when a diesel engine starts to run away and the engine’s RPM exceeds the red line, the ShockerPASS will activate and immediately close off the engine’s air supply. Another way to stop a diesel engine runaway is a preventative shut off whenever there are hydrocarbons in the air. To learn more about preventing diesel runaway before it happens, check out our ShockerEDGE!

Resetting your positive air shut off system is entirely dependent on your individual installation. When you purchase a positive air shut off system and install it in your diesel engine, you’ll be informed if it’s an automatic reset or manual reset. If your system is a manual reset, it will require the operator to turn a knob or lever back to the run/open position. If your positive air shut off is an automatic reset, it will return to the run/open setting after a set period of time. If you are unsure what reset system is right for you, we recommend an automatic reset as there is less room for user error!

Positive air shut offs need to be installed within your diesel engine so they are safely and effectively close the intake valve and stop your diesel engine from running. The ShockerPASS valve is installed in the air intake air piping as close to the intake manifold as possible for optimal effectiveness. You can check out our installation manuals to know how to install a ShockerPASS specific to your engine, or have one of our expert team members perform the installation.

Positive air shut offs work by activating the valve and closing off the air supply to the engine. Shut offs can be activated either manually or automatically, meaning either an operator needs to flip a switch or press a button to activate the shut off valve, or the shut off is connected to your engine’s RPM source and will automatically activate once it hits a certain RPM. At Headwind Solutions, we would recommend a positive air shut off valve that has both automatic and manual capabilities, ensuring that you can prevent diesel runaway manually if needed, but there is an automatic shut off to prevent the risk of user error.

The average diesel engine truck does not need a positive air shut off valve. If you work in the energy sector, typically a positive air shut off valve will be required to bring your truck on site. Many workplaces will require diesel engines to have shut off valves, and if you work in areas that have a risk of gas leaks and hydrocarbons in the air, having a positive air shut off valve is the safest option!

No, gas engines don’t need positive air shut off valves as they don’t run the risk of ‘running away’ like a diesel engine does. That doesn’t necessarily mean that gas engines are safer, though. Because of the composition of a gas engine, they are far more likely to act as an ignition source, which is why diesel engines with positive air shut off valves are the preferred industry engine.