How to Change an Oil Bath Air Filter

Change your oil bath air filter more often in dusty conditions.

Oil bath air filters are still in use on tractors and most two-cycle engines (ATVs, scooters and more). These filters use a foam soaked in oil and a bottom oil reservoir (built inside the filter) to clean the air of dust and debris before it reaches your engine. You can change an oil bath air filter easily and you should do do once a year. Changing the filter is a much easier process then cleaning it, which you should do after every 8 hours of engine use.

Things You'll Need

• Owner's manual
• Socket set
• Oil bath air filter
• Plastic bag
• Oil

Instructions

1. Remove the air intake from your engine. Follow the instructions in your owner's manual to do this as some intakes are bolted onto the air filter housing and some are attached with clips.

2. Unscrew and remove the oil bath air filter retaining bolt. Some models will have a locking wing nut that you can unscrew by hand while others will require a socket wrench to loosen the bolt. After the bolt is loosened pull it out of the center of the oil bath air filter and lay it down on a clean surface.

3. Lift the old oil bath air filter out of the air filter housing by grasping the plastic top and pulling it free.

4. Pour a cup of new oil into a plastic bag (preferably the kind that you can seal at the top).

5. Put your new oil bath air filter into the plastic bag and seal the bag. Work the oil into the filter by rolling the filter in the oil and kneading the oil into the foam through the bag. When the filter is evenly coated, remove it from the bag.

6. Place the filter into the air housing with the plastic housing of the filter facing up (the bottom of the filter is metal).

7. Replace and tighten the retaining bolt and then reinstall the air intake.

Tips & Warnings

• If you don't have an owner's manual that will tell you what type of oil to use on your filter and you cannot find the specifications by searching online, use the same weight of oil as is used to lubricate the engine.

• Do not let dirt or other debris coat the retaining bolt for the oil bath air filter. If the bolt becomes dirty it can introduce the debris into the engine and cause internal damage.

References

• Yesterday's Tractor: Tuning Up Your Tractor: Oil, Oil Filter and Air Breather
• Vintage Tractor Engineer: Oil Bath Air Cleaners for Tractors
• Utilityoffroad.com: Air Filter Maintenance

Resources

• Animated Engines: Two Stroke Engines