How to Change Primary & Secondary Fuel Filters on a Semi Tractor

Replacing the fuel filters in your tractor trailer is a quick and simple task. You will need to determine what type of diesel motor you are replacing the filters in. When you have determined the type of diesel, you will want to buy the filters from that distributor. Caterpillar filters will work best when used on Caterpillar motors. Call your local truck dealer and they will be able to provide the best filter for your diesel motor.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Fuel filter wrench
• Two gallons of diesel fuel
• Two new filters

Replacing the Fuel Filters

1. Open the hood of the truck by unsnapping the straps and pulling the hood toward you. You will notice two large filters on the driver's side of the motor.

2. Remove the primary filter with a fuel filter wrench. Clamp the filter with the wrench and turn to the left. You can use a pair of large channel locks if the filter wrench is unavailable.

3. Remove the smaller filter behind it. Be sure to remember which filter went to the front.

4. Fill the new filters with diesel fuel. The filters need to be filled with diesel as the motor will not run till the filters are full.

5. Lubricate the gasket of the filter with a dab of engine oil. Rub the oil around the gasket till the whole gasket is moist.

6. Attach the new filters to the fuel assembly. Tighten till the filters are snug. The gasket will seal when tight.

7. Crank up the truck. Let the truck run long enough to circulate the fuel through the lines. Run the engine for at least five to 10 minutes.

Tips & Warnings

• In the instance the primary filter is a fuel-water separator unit, you will need to disassemble the housing by twisting the black cap around the middle of the assembly. The filter can be removed from the housing by twisting the filter counterclockwise.

References

• Fleetguard Training Manual on Fuel Systems and Filters