Changing Fuel Filter Water Separators: Step-By-Step Guide

Changing the fuel filter water separator on your boat or RV is a relatively straightforward process, but it requires careful handling of fuel and attention to safety. Before starting, ensure you have the necessary tools and safety equipment, including rags, a catch pan or bucket, and safety gloves and goggles. Begin by locating the fuel filter water separator and draining the fuel from it, if possible. Some separators have a drain valve or a bottom drain that can be opened to release the fuel. If your separator is mounted higher than the fuel tank, you may not need to worry about fuel gushing out during the process. However, it is always a good idea to clamp the fuel line as a precaution. Once the fuel is drained, remove the old filter. This typically involves unscrewing it, but be cautious as some filters may be tightly secured. Using a filter wrench or long-neck adjustable pliers can help, but be careful not to damage plastic components. When installing the new filter, it is recommended to coat the gasket with a small amount of oil and tighten it by hand, being careful not to over-tighten. Finally, prime the system and test for leaks. It is also a good idea to inspect the fuel in the old filter for any water or contaminants.

Unscrewing the fuel/water separator

To unscrew the fuel/water separator, you will need a truck filter wrench. Before you begin, place a catch pan under the filter housing and open the drain at the bottom of the filter to release any remaining fuel. Once the filter is drained, you can start to unscrew it.

It is important not to over-tighten the new filter when screwing it back on. Smear a little oil on the rubber gasket, then tighten it by hand. Once the gasket makes contact, turn it by three-quarters to one turn more, and it should be secure.

If you are having trouble removing the filter, try using a rubber strap-type pipe wrench. You could also try using a standard pipe wrench, but be careful not to apply too much force, as this could damage the filter housing. If the filter is really stuck, you might need to use a tool like Freeze-Off to help loosen the rubber seal.

Using oil on the new filter/gasket

When installing a new fuel water separator, it is important to use oil on the new filter or gasket. This is a crucial step to ensure the longevity and performance of your engine. Here are some detailed instructions on using oil on the new filter or gasket during the installation process:

Before installing the new filter, it is essential to clean the area where the gasket will make contact with the engine. Use a degreaser to thoroughly clean the surface, removing any dirt, grime, or old gasket material that may be stuck to the mounting surface. This step ensures that the new gasket forms a tight seal with the engine.

Once the surface is clean, it is now time to apply the oil to the new gasket. Take a small amount of fresh, clean oil and use your finger to spread a thin coat onto the gasket. This step will help the gasket to not stick to the engine and make it easier to remove in the future. It also ensures that the gasket does not bunch up or bind when tightening the filter.

Some people prefer to use silicone grease or spray lubricants like WD-40 on the gasket instead of oil. This is also an acceptable practice and can make the installation process a bit cleaner. However, if you do not have silicone grease or WD-40 readily available, using a small amount of oil will work just fine.

After applying the oil to the gasket, carefully install the new filter, ensuring that the gasket is properly seated and snug in the filter baseplate. Be careful not to over-tighten the filter, as this can crush the gasket and cause leaks. Hand-tightening the filter and then giving it a quarter-turn is usually sufficient.

Finally, once the new filter is installed, it is important to check for leaks. Start the engine and let it idle at a fast speed, then take it for a short test drive close to home, monitoring for any signs of leaks. If leaks are detected, tighten the filter slightly and re-check. If leaks persist, consult a mechanic to ensure the filter is installed correctly.

Draining the fuel filter

To drain the fuel filter, first, make sure all electricity is turned off. Place a catch pan under the filter housing and open the drain at the bottom of the filter. If there is no drain, you will need to loosen the plug or tap on the filter. You may also need to release the vent valve at the top of the filter housing to allow for easier drainage. If you cannot find a vent valve, carefully unscrew the uppermost fuel pipe union connected to the filter casing.

Once the filter is open, the fuel and water should begin to flow out. Let the fluid drain until only clean, pure diesel fuel is flowing out. Then, close the plug or tap and retighten the vent valve or fuel pipe. Check the water that has drained out and consider obtaining diesel fuel from a different source if it is particularly dirty or contains a large amount of water.

It is recommended that you check your water separator weekly to understand how quickly it fills up under normal driving conditions. This will help you identify any issues with your fuel source and prevent engine damage.

Using a wrench to remove the filter

To remove the filter using a wrench, you'll first need to ensure you have the correct size and type of wrench for your specific fuel filter. If you're dealing with a tight space, consider using a specialised filter removal tool designed for this purpose. Before attempting to remove the filter, it's important to relieve the pressure in the fuel system. You can do this by opening a valve on the fuel line near the filter, or by briefly starting the engine and letting it run until it stalls.

Now, locate the fuel shut-off valve and turn it to the "off" position to prevent fuel flow. Then, use your wrench to loosen and remove the filter bowl, turning it counter-clockwise. Be careful not to damage the housing. Once the bowl is removed, drain any accumulated water from it.

If your fuel filter has an air stem similar to a car tyre, you can use a valve stem tool or a small screwdriver to slowly and carefully open the valve. This will release any trapped air or pressure in the fuel system, reducing the risk of fuel spray during the filter replacement process. Remember to always wear safety goggles and have a cloth or rag nearby to catch any escaping fuel.

Clamping the fuel line

Before you begin, ensure you have the necessary tools and supplies, including a fuel water separator kit, fuel system-grade thread sealer, marine-grade silicone sealant, proper diameter hose clamps, a universal wrench kit, and a scrap of plywood if a mounting plate is needed.

Now, let's get started with clamping the fuel line:

• Open all hatches to ensure proper ventilation. It is important to work in a well-ventilated area when dealing with fuel systems.
• Cut the supply hose at the mounting location. You may need to use a hose cutter or a similar tool for this step.
• Drain the contents of the supply hose. Place a container or a pan underneath the hose to collect the drained fuel.
• Plug the line by inserting a bolt and securing it with a hose clamp. This will prevent fuel leakage during the installation process.
• Install the new fuel filter water separator according to the manufacturer's instructions. Make sure to follow the correct installation procedure for your specific model.
• Double-check that the hoses are properly connected to the fuel filter's ports. Ensure they are firmly clamped without pinching the hoses. You may need to use new hose clamps for a secure connection.
• Once the new fuel filter water separator is installed, you can now unclamp the fuel line. Loosen the hose clamp that you previously tightened to secure the bolt.
• Remove the bolt that you inserted earlier.
• Reconnect the supply hose to the new fuel filter water separator. Ensure that the hose is securely clamped and there are no leaks.
• Start the engine and check for any leaks. Perform a test run to ensure that the new fuel filter water separator is functioning properly.

Remember to always exercise caution when working with fuel systems. It is important to work in a well-ventilated area and to avoid any potential sources of ignition. Follow the specific instructions provided by the manufacturer of your fuel filter water separator for the best results.

Frequently asked questions