13.4 How to Replace the Fuel Filters

Filters are an integral part of the fuel system. Proper filter selection and maintenance are important to satisfactory engine operation and service life. Filters should be used to maintain a clean system, not to clean up a contaminated system.
An optional fuel/water separator may be installed in place of the standard primary filter.

13.4.1 Replace Main Fuel Filter Element

Change the main fuel filter element as follows:
1.
Open the fuel tank fill cap to release pressure in the fuel system. Replace and tighten the cap.
2.
Clean the outside of the fuel filter housing ( See Figure "Main Fuel Filter" ).
 1. Filter Housing Cap
 2. O-ring
 3. Filter Element
Figure , Main Fuel Filter
3.
Using a 36-mm socket, unscrew the cap on the main fuel filter housing. Remove the cap and lift the filter element a short distance within the filter housing allowing the fuel to drain off the filter.
4.
Remove the filter element from the cap and clean the filter cap. Discard the filter element and the O-ring from the cap.
NOTICE
To prevent damage to the filter housing, do not allow dirt to get into the filter housing.
5.
Clean the filter housing cap.
6.
Replace the O-ring.
7.
Lubricate the rubber seal, on the bottom of the filter element with a light coat of fuel oil and insert it into the filter housing. Push down and rotate the filter element while installing to ensure it is seated properly at the base of the housing.
Note : A properly seated filter element will hold the fuel in the filter housing and prevent it from draining back to the tank. If the fuel does not stay in the housing the element is not seated properly, repeat steps 1 and 2.
8.
Fill fuel filter housing with clean fuel oil.
9.
Install a new O-ring on the filter cap and screw the cap onto the filter housing. Tighten the cap to 25 N·m (18 lb·ft).
10.
Prime the fuel system by working the hand pump until resistance is felt.
Note : There should be a strong resistance in the hand pump, caused by the pressure build-up within the fuel system.
11.
Crank the engine for 30 seconds at a time, but no longer. Before cranking again, wait at least two minutes, then crank again. The engine should start within four 30-second attempts.
12.
Once the engine starts allow it to idle for at least one minute or until idle is smooth before applying the throttle. Check the fuel filter housing for leaks.

13.4.2 Fuel/Water Separator Prefilter Element Cleaning

Clean the prefilter element as follows:
1.
Loosen the bleed screw. See Figure "Fuel/Water Separator" .
2.
Unscrew the drain plug and drain the fuel in the prefilter.
3.
Twist off the sight bowl and remove the filter element from the separator head.
4.
Separate the sight bowl from the filter element. Clean the sight bowl. Discard the old filter element and both O-rings.
5.
Replace the filter element and O-rings.
6.
Assemble the sight bowl and the prefilter element.
6.a
Lubricate one O-ring with a light coating of engine oil and insert it into the sight bowl.
6.b
Screw the prefilter element and sight bowl together.
7.
Assemble the prefilter element and the separator head.
7.a
Lubricate the other O-ring with a light coating of engine oil and insert it into the open end of the prefilter element.
7.b
Screw the prefilter element onto the separator head and tighten firmly, using hands only.
Figure , Fuel/Water Separator
Note : Do not use tools to tighten the prefilter element.
8.
Tighten the drain plug.
9.
Prime the fuel system.
9.a
If equipped with a hand pump on the fuel/water separator, work the hand pump until resistance is felt.
Note : There should be a strong resistance in the hand pump, caused by the pressure build-up within the fuel system.
9.b
Crank the engine for 30 seconds at a time, but no longer. Before cranking the engine again, wait at least two minutes. The engine should start within four 30 second attempts.

13.4.3 Replace Davco 382 Fuel Pro®Fuel/Water Separator Element

Replace the fuel/water separator element as follows:
Figure , Davco 382 Fuel Pro®Fuel/Water Separator
1.
Remove the vent cap, open the drain valve and drain fuel into approved container, until level is below the collar. See Figure "Davco 382 Fuel Pro®Fuel/Water Separator" .
2.
Using a collar wrench remove collar and cover.
3.
Remove the filter element from the separator head and discard filter cover seal and vent seal. Dispose of filter properly.
4.
Clean the cover and the mounting surface on the body.
5.
Install the filter element with bottom grommet and new cover seal. Install the cover and collar. Hand tighten only.
6.
Fill cover completely with clean fuel through the vent cap opening.
7.
Replace seal on the vent cap and install in cover. Hand tighten only.
Note : Do not use tools to tighten the collar or vent cap.
8.
Tighten the drain plug.
9.
Crank the engine for 30 seconds at a time, but no longer. Before cranking the engine again, wait at least two minutes. The engine should start within four, 30 second attempts.
10.
Start the engine and raise the rpm for one minute to purge the air. After the air is purged stop the engine, loosen the vent cap until the fuel level lowers to just above the collar. Tighten the vent cap by hand. Check for leaks.

13.4.4 Replace Davco 382/382E Fuel Pro® Fuel Filter Element

The Davco 382/323E Fuel Pro diesel fuel filter system consists of a permanently mounted fuel processor, a replaceable filter element and sealing grommet assembly, a filter spring, a see-thru cover and seal, a cover collar, and a vent cap and seal. See Figure " Davco 382E Fuel Pro Fuel Processor Assembly" .
Figure , Davco 382E Fuel Pro Fuel Processor Assembly
The system also includes a fuel heater element, thermostatic switch and wiring harness.
Replace the element as follows:
1.
Shut down the engine and allow it to cool.
2.
With the engine at ambient temperature and cool to the touch, place a suitable container under the filter.
3.
A fuel shutoff valve may be installed on the discharge side of the fuel filter. If installed, turn the handle on the shutoff valve to the closed position (perpendicular to the valve).
4.
Open the drain valve at the base of the fuel processor and drain the fuel until it is below the bottom of the filter in the see-thru cover. Close the drain valve. The fuel may be returned to the tank.
5.
Using filter collar/vent cap wrench Davco part number 382002 or equivalent, remove the collar by turning counterclockwise. Remove the cover, filter spring and cover seal ring by lifting straight up and over the filter element.
6.
Remove the element from the center stud (fuel outlet pipe) by pulling upward and twisting slightly.
Note : Current filter elements include an integral sealing grommet. If a former element is replaced, make sure the separate sealing grommet is removed from the center stud before installing the new element.
7.
Dispose of the used element and grommet in an environmentally responsible manner, according to federal (EPA) and/or state recommendations.
8.
Check to make sure the sealing grommet is included in the base of the replacement filter element, then install the element onto the center stud by pushing down and twisting slightly.
9.
Check to make sure the spring is installed at the top of the cover. If missing, this spring must be replaced to insure proper filter operation. Wipe the cover lip and cover seal clean.
NOTICE
Do not use a wrench of any kind to tighten the collar, since this may lead to overtightening, which can damage the collar and/or the cover.
10.
After making sure the seal is properly positioned at the base of the cover, install the cover and collar onto the fuel processor. Tighten the collar by hand until secure.
11.
Using filter collar/vent cap wrench 382002 or equivalent, remove the vent cap from the top of the cover by turning the cap counterclockwise. Fill the cover full of clean fuel. After making sure the O-ring seal is installed on the vent cap, reinstall the cap and tighten by hand .
NOTICE
To avoid cover or vent cap damage, do not use tools to tighten the vent cap.
12.
Open the fuel shutoff valve (if installed) and start the engine. When the lubrication system reaches its normal operating pressure, increase engine speed to high idle for 2 to 3 minutes.
NOTICE
Do not allow the fuel level in the see-thru cover to fall below the top of the collar, since this may lead to interruption of the fuel flow and engine stalling.
13.
After the air is purged and with the engine still running, loosen the vent cap. The fuel level in the cover will start falling. When the fuel level falls to the top of the collar, tighten the vent cap quickly by hand .
14.
Shut down the engine and tighten the collar again by hand . Restart the engine and check for leaks.
Note : The filter cover will not fill completely during engine operation. It will gradually fill over time, and the fuel level will rise as the filter medium becomes clogged. The filter element does nor require changing until the fuel level has risen to the top of the element, or after one year of service, whichever comes first.