Donaldson Air Filter

Discussion in 'Mechanic and Repair' started by Larry Davis, Nov 6, 2005.

  1. Larry Davis

    Larry Davis LawnSite Member
    Messages: 116

    To Restrorob or anyone else with technical knowledge on this:

    I have a Kohler 28 EFI with Donaldson Air Filter. There is a clear plastic "air restriction indicator" that is supposed to take the guess work out of when to change the filter elements. I have been mowing in extremely dusty conditions (mulching leaves) for the past 3 weeks with no rain for over a month. More dust than I've ever seen. So thick that I've been wearing goggles and surgical masks and it still gets into my eyes and lungs. Anyway ..... my question is ........ just how accurate is this restriction indicator? After all of this dust I would have to believe the elements are saturated but the indicator has barely moved! And, there is a warning in the owner's manual that says people cause more damage to the engine by checking the paper elements frequently and not going by what the indicator shows.

    What would you suggest?

    Larry Davis
  2. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Those things are pieces of sh!t man. Just set yourself up a regimine. I change mine every 100 hours. If you think the conditions have been tough, use common cense and change that sucker.
  3. Brianslawn

    Brianslawn LawnSite Silver Member
    Messages: 2,002

    you should be tapping filter a couple times a day in those conditions replace weekly or more. do you have inner foam filter, too?
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I believe what the owners manual is referring too is people taking the element out and putting 120lbs. of compressed air through it cleaning it. That is a big no no, It opens the pours of the paper and no longer filters properly. If you do have the inner pre filter that is even a bigger no no because it is made of a fiber material that a hole can be blown through. I don't really know how accurate the indicators are because I've never had one come in clogged enough to see it move.
    This is what I do, I have a long tip blower and I blow them from the inside out LIGHTLY, Then blow horizontally with the filter length LIGHTLY then once more from the inside LIGHTLY. Same with the pre cleaner, I believe you will see the paper filter all brown and grungy looking and feel the need for a new one long before the indicator shows red. In the conditions you described above I would suggest doing this daily just to prolong the life of the filter, As you know they are not very cheep.
  5. Larry Davis

    Larry Davis LawnSite Member
    Messages: 116

    Thanks for the responses. I'm just trying to do what's right to get the longest life out of my engine. However, here is exactly what the Hustler owner's manual says concerning the Domaldson Filter:
    Overservicing occurs when an air filter element is removed for cleaning or replacement before it is necessary. Each time the filter is removed a small amount of dirt and dust could fall in the intake system. A partially dirty air filter element works better than a new element. Therefore, a dirty filter element is not bad for the engine unless it is excessively restricting the air flow and engine performance is affected. The reason is simple. The media in the filter must be porous to allow air to pass through it. When dirty air passes through the filter, the dirt plugs some of the holes in the media and actually acts as part of the filter media. When the next round of dirt enters, the first dirt helps filter out even smaller particles making the filter even more efficient." Then, in bold face letters: "Do Not Clean Elements. Replace With New Elements Only."

    Any comments?

  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    "Each time the filter is removed a small amount of dirt and dust could fall in the intake system"
    I could see this if the assembly is mounted vertically but highly unlikely mounted horizontally especially with a pre filter. There would be a better chance of it happening if you did leave it in there until it clogged up completely, But still not with a pre cleaner.

    "dirt plugs some of the holes in the media and actually acts as part of the filter media"

    I must be missing something here ;) IMO, If the dirt plugs the media then more dirt on top of that dirt is going to plug the media even more. ???

    I do know manufactures say not to use compressed air to clean filters BUT if done properly can increase the life of the element and reduce fuel usage.

    One last thing ; I Really don't care who says what.....There is NO way I'm leaving the air filter in anything I own until it gets all clogged up.

    I understand wanting to get the most life out of your investment, So now you have my opinion and the ball is in your court as to how you want to service your unit.

    Take Care
  7. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    There is a filter minder on my diesel, at 3100 rpms running 30 lbs of boost with 15000 miles on a dirty filter, the minder POS is only pulled down to HALF!!! That is not even in the red. Those show no indication of how restrictive the filter is.
  8. DEEJ

    DEEJ LawnSite Member
    Messages: 230


    I am constantly surprised at how clean the Donaldson Filter setup stays. I check mine on my 28EFI semi-regularly and it remains very clean. From my experience procedures like opening it twice a day and tapping the dirt off are totally unnecessary. It may be required with lesser systems or more exposed systems, but the Donaldson system on top of the 28 EFI stays very clean, even in dusty dusty conditions. ... just my experience with this setup on a 28EFI and a 26 EFI on two 60" Lazers ...

  9. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    I second that. We get Walkers in with them. Some times they get busted or messed up some how and we just remove them and plug off the hole with a pipe plug. I say most people never read them any way. And like was said blowing them out with compressed air can mess a air filter up big time. It really should not be done at all. If you blow a hole it the filter it is trashed.

    And remember if you are running a Kohler EFI engine use BOTH the big out side filter and the small inside filter.
  10. Jman

    Jman LawnSite Member
    Messages: 217

    I believe the filters showed NEVER be blown out with anything. If they are dirty enough to need cleaning, they should be changed. A filter allows a very large volume of air to pass thru over a very large surface area. No matter how low the pressure is on a hose or adapter used to blow air, especially thru the filter, it is a very concentrated direct amount of air. The paper fibers will open up slightly.

    I like the filter minders. They are designed for the small displacement air cooled engines. The ones for the Kohler hit the red zone when vacuum inside of the filter hits 8 inches H2O of vacuum. This isn't much, it's not like when people messure vacuum in a car engine which 8 inches of mercury vacuum is a ton. The filter minders for large diesel engines don't hit the red zone till 24-30 inches of H2O vacuum. One other word of advice, don't remove the heavy duty air filter and tap it off. Once teh filter is removed it allows the seal on the rubber end to be brocken. The rubber seal is nice and soft when new. As it heats up and cools down on the engine it takes a "set". When you put a used filter back over the plastic housing it doesn't seal as effeciently as it did. Visually inspect, if dirty, replace it.

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