Changing Fuel Filters: Paccar Motor Maintenance Guide

Changing the fuel filter on a Paccar motor can be a challenging task. While the specific process may vary depending on the model and year of the vehicle, there are some general steps and considerations to keep in mind. It is important to locate the fuel filter, which is usually found near the engine, and identify the type of fuel filter your vehicle uses. Before beginning any work, ensure you have the necessary tools and safety equipment, such as gloves and eye protection. It is also crucial to relieve the fuel system pressure and disconnect the battery before proceeding. Once the fuel filter is accessed, carefully drain any remaining fuel and replace the old filter with a new one, ensuring all seals and O-rings are properly lubricated and sealed. Reattach the fuel lines and any other components that were removed, and prime the fuel system by pumping the primer pump until the new filter is full and pressurized. Finally, reconnect the battery and start the engine to ensure the new fuel filter is functioning properly.

Bleeding the fuel system

Step 1: Prepare the Fuel Filters

Before beginning the bleeding process, it is important to fill the fuel filters with fuel. Start by filling the spin-on filter as much as possible before installing it. Then, fill the separator filter as much as you can before tightening it up. This step ensures that the filters are ready to be pressurised.

Step 2: Close the Bleed Ports

Unlike traditional methods of removing air from fuel systems, it is crucial to keep all bleed ports closed during the priming process. This means you should not open the bleeder screw near the primer pump, as some sources suggest.

Step 3: Pump the Primer Pump

Locate the manual primer pump on the main fuel filter. Start pumping it vigorously without opening any bleed ports. Continue pumping until you hear the pressure release valves in the head start clicking. This sound indicates that both the separator filter and the spin-on filter are full and pressurised.

Step 4: Start the Engine

After ensuring that the filters are full and pressurised, you can attempt to start the engine. With the fuel system primed correctly, the engine should fire up smoothly and quickly without any issues.

Troubleshooting:

If you encounter difficulties getting the engine to start or if it loses prime and dies, there are a few additional steps you can try:

• Work the O-ring on the housing containing the large fuel filters back and forth, and then try to crank the engine.
• Apply very low air pressure (5 PSI or less) to one fuel tank with the vents closed on both tanks. Bleed air from the primary filter housing and then from the secondary housing or where the line was connected to the head.
• Loosen one injector nut and add a small amount of starting fluid in the air filter to keep the engine running.

Remember to exercise caution when working on the fuel system, as high pressure is involved. Always refer to the recommended procedures and instructions specific to your Paccar MX13 engine for the most accurate and up-to-date information.

Using a hand primer

To change the fuel filter on a Paccar motor, you'll need to use a hand primer. Here's a step-by-step guide on using a hand primer:

First, locate the hand primer next to the main fuel filter. Unlock it, and the handle will come up. Start pumping the hand primer. Be prepared to pump for a while, as it can take a significant amount of time—even up to 15 minutes in some cases. You'll need to keep pumping until you feel resistance, and it gets hard to pump.

During this process, you may notice that the hand primer button gets sucked back down when the motor is started. This could be due to a blockage on the intake side or a faulty fuel pump. If you encounter this issue, try blowing air back from the filter towards the tank to check for any blockages.

If you're still having trouble, try taking the feed to the injector pump off the filter housing, then prime until the fuel starts coming out. Put the feed back on, and this should help to resolve the issue.

Additionally, ensure that the filter is completely primed before starting the engine. It's important to fill the spin-on filter and separator filter with fuel as much as possible before tightening them up. This will help ensure that the engine fires up smoothly.

Filling the spin-on filter

Firstly, locate the spin-on filter on the Paccar engine. It is usually found near the main fuel filter housing. Before filling the spin-on filter, ensure that you have the correct fuel filter for your Paccar model. Refer to your owner's manual or consult a Paccar technician if you are unsure.

Once you have the correct filter, remove the old spin-on filter by unscrewing it in a counter-clockwise direction. Place a drip pan underneath to catch any residual fuel. Take note of the filter's orientation and markings to ensure proper installation of the new filter.

Clean the area around the filter mounting point to prevent any debris from entering the fuel system. Now, take the new spin-on filter and fill it with fuel. You can use a funnel to avoid spills and ensure the filter is filled to the recommended level. Check your Paccar manual for the specific fuel type and capacity.

After filling the new spin-on filter, carefully screw it into place by hand. Make sure it is tightened securely, but be careful not to overtighten it. Once the new filter is installed, check for any signs of fuel leaks.

Finally, prime the fuel system by pumping the primer pump until it becomes hard or until you hear the pressure release valves clicking. This may take several minutes, so be patient. Refer to the Paccar troubleshooting guide or seek assistance from a qualified technician if you encounter any issues during the priming process.

Lubricating the o-ring with Vaseline

To lubricate the o-ring, first, remove the old fuel filter by unscrewing it from the engine. Once the old filter is removed, you will be able to see the o-ring, which is typically located on the fuel filter housing. Clean the o-ring and the surrounding area with a soft cloth to remove any dirt, grease, or debris.

Before installing the new fuel filter, apply a thin coat of Vaseline to the o-ring. The Vaseline will act as a lubricant, allowing the o-ring to create a tight seal and preventing it from drying out and cracking over time. It is important to use only a small amount of Vaseline, as too much can cause the o-ring to slip out of place.

Once the o-ring is lubricated, carefully screw the new fuel filter into place, taking care not to overtighten it. Make sure that the o-ring is seated properly and is not twisted or pinched, as this can cause leaks. After the new fuel filter is installed, check for any signs of fuel leaks and ensure that the area is clean and free of debris.

By following these steps and properly lubricating the o-ring with Vaseline, you can help ensure a secure and long-lasting seal for your Paccar motor's fuel filter, maintaining the engine's performance and preventing potential issues.

Pumping the primer

To prime the fuel system of a Paccar MX13 engine, you need to locate the hand primer pump on the main fuel filter. Unlock the pump, which will cause the handle to pop up. Then, start pumping the primer. It may take a while, but you should continue pumping until the handle becomes hard to press. Then, lock the pump back into place.

There is also a manual primer pump on the main fuel filter. Pumping this for a long time may help get the truck to fire up.

Another method is to fill the spin-on filter and separator filter with as much fuel as possible before installing and tightening them. Then, start pumping the primer pump without opening any bleed ports. Keep pumping until the separator filter is full and you can hear the pressure release valves in the head clicking.

If you have a see-through filter on the firewall, pull the filter, lubricate the o-ring with Vaseline, and put the cover back on. Then, fill the filter with fuel and pump the primer again. You should see bubbles in the glass.

Frequently asked questions