Talking About Auto Maintenance and Service

Understanding The Dangers Of Installing A Diesel Fuel Shut Off Valve Backwards

1 December 2015 by Jason Lopez

If you have a diesel vehicle with a shut off valve attached to the fuel line, then you may need to replace this valve at some point as you own the car. This part is responsible for stopping the fuel from running to the engine. You will likely know that replacement is needed, because the car will likely continue to run when you turn the key to the off position. To fix this problem immediately, you can manually shut off the valve by pressing the small lever on the side of the part or the housing covering it. After doing this, get a new part from your local auto store. If you decide to change the valve, make sure to consider the information below about the dangers of installing the part backwards and how the diesel engine can be shut off if you do install the part backwards for some reason.

Dangers of Installing A Diesel Fuel Shut Off Valve Backwards

If you are familiar with car parts, then you may notice how the shut off valve was situated when you initially removed it. However, if you are a novice, you may forget to consider this. The diesel shut off valve works on a vacuum type of fuel system where the air will be sucked through the fuel lines with natural pressure. Unlike other types of engines that rely on electronic fuel pumps and sparks, the fuel will continue to run to the engine even when the car is shut off. The shut off valve keeps this from happening by pulling on the shift linkage to downshift the car until it turns off. A small lever on the shut off valve will complete this task.

Unfortunately, if you accidentally install the valve improperly, shutting off the car will actually push the lever attached to the shift linkage. This can happen if the device is connected on the wrong side of the linkage attachment. This will cause it to shift upward and the engine will throttle and produce a great deal of power without the vehicle moving. This can cause the engine to quickly overheat, because very little air will be moving through the engine compartment to cool it. If a gasket or the engine block cracks due to the heat, then this may be an extremely expensive fix.

Emergency Shut Off Procedures

If possible, take pictures as you remove the shutoff valve from the shift linkage attachment so you can reference this as you add the new device. Also, keep in mind that you can shut off the engine fairly quickly in an emergency if there is a need. You can do this by cutting off the air to the engine. Fuel and air is mixed together while an engine is running. Without enough air, the engine will stop. Before you start your car after replacing the shutoff valve, remove the air filter from the engine air intake. This will allow you to plug the intake with a rag for a few minutes if your car throttles uncontrollably when you turn it on. Also, some vehicles will come with an emergency air intake shutoff valve for this reason. Search for one of these valves around the air filter. Do not panic and force your hand over the intake though. Suction is strong and this may cause a hand injury.

Also, some diesel cars will come with an emergency shut off lever or button in the engine compartment that you can activate to turn off the car. This device is usually red and says stop on the side or top of it. Generally, a lever will be included that you will have to push or pull to force the shift linkage to downshift. You may need to activate the lever with a bit of pressure if you need to use it, because the improperly installed fuel shut off valve will still be trying to force the linkage to shift upward.

You may find yourself with a fuel shutoff valve that needs replacement if you have a diesel powered car. You will need to understand that it can be dangerous to install the part backwards. If you feel that the resulting issue is a scary one to deal with in an accidental situation, then think about speaking with your local mechanic about replacing the part for you. You can also check out a company like Diesel Tech Industries for more information on shut off valves.

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