Oiled Air Pre-Filters

Discussion in 'Mechanic and Repair' started by khutch, Apr 3, 2005.

  1. khutch

    khutch LawnSite Senior Member
    Messages: 495

    Some oiled, some not, of course by mfg.
    Would seem like oiled filters would do a better job...What is the theory here?
  2. lawnandplow42

    lawnandplow42 LawnSite Senior Member
    Messages: 508

    You're talking about the foam filter around the paper one right?
  3. Travis Followell

    Travis Followell LawnSite Silver Member
    from KY
    Messages: 2,206

    Thats the one he's talking about. The pre cleaner. One thats oiled should do a better job because the oil will trap the dirt and a lot of particles would go right through an element thats not oiled. I don't know why a mfg wouldn't recommend oiling the foam pre cleaner. Maybe to just get you to buy more air filters because they will get dirty quicker.
  4. lawnandplow42

    lawnandplow42 LawnSite Senior Member
    Messages: 508

    not sure, but i always lightly oil mine
  5. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    Is Kawasaki the one not recommending oiling the prefilter?
  6. Drew Gemma

    Drew Gemma LawnSite Bronze Member
    Messages: 1,508

    you are not supposed to oil the prefilter as far as I know. But the oil is a better idea it actually collects the dirt keeping it from getting sucked in. Then it also helps create a vacum. Look at the k&n filter system same principle but in one filter.
  7. spoolinaround

    spoolinaround LawnSite Senior Member
    Messages: 331

    the only concern I have is the oil residue could contaminate the paper element and load it up and cause airflow issues
  8. khutch

    khutch LawnSite Senior Member
    Messages: 495

    I've got two Kawi's, a 12.5 and a 17. Smaller one Kawi recommends oiled pre-filter, on the 17 they don't (???)......I think I like the idea of the oiled pre-filter, but just not sure why a mfg. would do it on some and not others. Doesn't have anything to do with selling you a filter because they are not consistant......
    Also by lightly oiling the pre-filter (as recommended) oil residue never really gets on the paper. I'm sure if you over oil it, you will get a clogged paper filter that will restrict air flow.
  9. Teiman

    Teiman LawnSite Member
    Messages: 103

    From what I've gathered by reading many posts
    on Kawis. They now walk a fine line (because of emissions)
    and their engines are more and more sensitive to air flow
    issues. Read some of the post about surging etc......

    I am looking into an aftermarket setup. Although the Kits
    offered by Enginaire and others don't seem to be EPA certified
    (someone correct me if I am wrong) sometimes they include new
    jets and even different carbs.

    Government mandated Emissions policy never takes into account things
    like the environmental cost of early engine failure. I figure its a wash
    environmentally if my engine last twice as long, requires fewer oil changes and puts out a little more smog.
  10. Mikes Machines

    Mikes Machines LawnSite Member
    Messages: 112

    Unless something has changed in the last couple years ALL pre filters that are foam need oil. Without the oil they are not doing their job. It is the oil that catches the dirt not the foam. As far as the theory that no oil on the filter is for emissions, dont believe it, the carb jetting is set to run epa lean with oil on the pre filter. With no oil on the filter the engine runs leaner yet. This can shorten engine life. If you dont believe me try it, run a few tanks through on a new spark plug with no oil on the filter then check the plug. It will be white, then run it with oil on the filter and recheck, it will be just a hair darker, if it was rich it would be black.

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