Kohler 25 not running well

Discussion in 'Mechanic and Repair' started by BufalinoLand, Jun 22, 2006.

  1. BufalinoLand

    BufalinoLand LawnSite Senior Member
    Messages: 400

    25 kohler air cooled,

    im the original owner, 1250 hours, i maintain it well

    new fuel filter, plugs 20 hours ago, took carb apart cleaned it, because it wasnt running full strength, would not idle either

    ran awsome, but problem is back,

    what should i do any ideas

  2. mike lane lawn care

    mike lane lawn care LawnSite Bronze Member
    Messages: 1,707

    that engine is very tired and used. fuel filter is a possibility, but more likely, is that there is a lot of internal stress and damage to the engine. if the machine is in good condition i would price a new engine.
  3. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    The 25hp Kohler was plauged with problems in the late 90's.

    How old is this unit?
  4. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Messages: 1,164

    Do you have an in-line spark tester, compression gage and leak down tester?
    If not or if you are not sure what any of these tools are I would take it to a good shop and have someone have a look at this engine. It could be something simple but without running these tests first and getting all the readings from each test there is no telling what is causing your issue.
    I have seen Kohlers run (bad) from a spark plug not tightened correctly in the head or an incorrect air gap so anything is possible you may get lucky or you may get bad news.
  5. tallimeca

    tallimeca LawnSite Bronze Member
    Messages: 1,229

    These motors had a ton of issues. Mainly head gaskets, head gaskets, headgaskets.

    With 1250 hours on it, i'd be willing to be it's just tired. If you pulled the heads and measured the bore, i'd bet it out of spec.

    Very common to see on walkers. Usually we see about 1500 hours out of these engines.

    That's all they are rated for by Kohler.
  6. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Check the intake gaskets. Remove the engine shroud and spray some WD-40 around the intake gaskets while the engine is running at either WOT or idle. If they are leaking then you will hear a difference in RPM and engine sound as you spray them.

    Leaking intake gaskets can cause a poor idle and will lean out the engine...Kohler 25's did have lots of headgasket troubles as well though.

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