There are two types of vent caps: The earlier vent cap has thin ridges around the outside edge. This vent cap should be hand tightened. If a collar wrench is used to tighten this type of vent cap, it may damage the vent cap material or the o-ring. The later vent cap is torque-controlled and has a wavy edge. This vent cap should be hand tightened until it "clicks". The vent cap is a serviceable part and will fit covers previously equipped with the "toothed" vent cap. The advantage is that the torque controlled vent cap cannot be over tightened.

1. Follow shop safety rules for service procedures. These may include chocking the wheels.
2. Check the DAVCO filter matrix or the tab on the page to ensure that you have the correct filter.
3. Place a drain pan under the Fuel Pro .
4. Use the DAVCO collar wrench to loosen the vent cap. Remove the vent cap from the clear cover and set it aside. Dispose of the o-ring. With a drain pan under the Fuel Pro or Diesel Pro, open the drain valve and allow the fuel to drain below the filter element. (On the Fuel Pro 382, this level is about an inch below the collar. On the Fuel Pro 482 and the Diesel Pro, this level is about two inches below the collar. Drain enough fuel so the bottom of the fuel can be seated onto the stud inside the Fuel Pro without sitting in fuel.)
5. Close the drain valve.
6. Use the DAVCO collar wrench to loosen the collar. Remove the cover and set them aside. Dispose of the o-ring.
7. Remove the filter by twisting it slightly and lifting it. Check that the grommet on the bottom of the filter is removed. If it remains on the stud, pull it off. Dispose of the filter and the grommet.
8. Use a shop rag to clean the threads and body. Inspect the surface where the cover o-ring rests for signs of wear or damage.
9. Inspect the body threads. If there is debris on the threads that is not easily removed with a shop rag, use a wire brush to clean the threads.
10. Clean and inspect the cover and vent cap. Remove and discard the o-rings. Clean the vent cap and check for any damage. Clean the clear cover and the collar. Inspect the spring and check that the spring is securely attached to the cover.
11. Look for cracks, nicks or damage to the clear cover or the collar.
12. Install the new o-rings on the vent cap and the cover.
13. Seat the filter on the filter stud. Press down on the top of the filter to make sure the grommet is completely seated.
14. Put the cover and collar over the filter. Hand tighten the collar, then use the collar wrench to make sure it is tightened securely.
15. Fill the Fuel Pro with fuel. Hand tighten the vent cap and turn on the engine. When the engine reaches its normal operating temperature, increase the RPM for one minute.
16. Open the vent cap and allow the fuel level to slowly drop below the collar. Hand tighten the vent cap. The fuel level should drop gradually. If the fuel level drops very quickly, this may mean that the one of the o-rings may be missing or that one of the o-rings may not be seated correctly. Check the cover and vent cap o-rings and follow the priming procedure again.

This video demonstrates:

• How to determine when to change the filter
• How to perform a filter change
• How to prime the engine after the filter change

Click on the video to start.