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Walker 20hp Kohler running on 1 cyl.

Discussion in 'Mechanic and Repair' started by mowmor, May 24, 2004.

  1. mowmor

    mowmor LawnSite Member
    Posts: 5

    My Kohler command 20hp seems to be running on only 1 cylinder. If I disconnect 1 plug wire there is no change in performance. If I disconnect the other plug wire the mower will not start. There is spark on both plugs and I have connected a timing light to both plug wires and am getting what appears to be a good strobe. Is it possible that one of the ignition modules good be bad and still be putting out spark? Any ideas would be appreciated.
  2. fixer67

    fixer67 LawnSite Silver Member
    Posts: 2,100

    First thing forget the timing light. Will the engine running unplug one of the plug wires and see what happens. Then shut the engine off and reconnect the plug wire. again with the engine running unplug the other plug wire and see what happens. A spark from wire to frame does not mean spark at plug. Sometimes is a spark is weak it will not fire under compression. A timing light is too easy to trigger. I can take mine and hook it to a battery and drag the pick-up coil across the work blanket and it will set off the strobe.
  3. ducky1

    ducky1 LawnSite Senior Member
    Posts: 252

    First I would try new plugs. Koher had a few problems with the rocker arms coming loose. Easy to check. Just remove the cover on the head and have a look and see. Could even be a blown head gasket. Good luck!
  4. P&C Lawn Care

    P&C Lawn Care LawnSite Senior Member
    Posts: 373

    If you have spark on both plugs you could have a stuck valve. If it is stuck open you are not getting any compression. How many hours is on this Kohler? I had a Briggs I/C that had a valve stick causing it to break a rod, Had to do the whole lower end with a new crank, wrist pins, and rods. I now use a liitle Marvel Mystery Oil in the gas from time to time to help lube the valves.
  5. VegetiveSteam

    VegetiveSteam LawnSite Senior Member
    Posts: 297

    Checking the rocker arms and push rods would be a good idea. Make sure nothing is broken or bent.

    To eliminate any question about ignition swap the ignition coils from one side to the other. If the problem follows the coil then you have your answer. If the problem stays with the original cylinder you know you have to keep looking.
  6. hc841

    hc841 LawnSite Member
    from oh
    Posts: 10

    you will likely find low compression on one cylinder...if you check
  7. AirCooled

    AirCooled LawnSite Member
    Posts: 30

    I agree with most of the above comments. It takes much more energy to fire a plug under compression than it does to fire one against the block. Thats why we have large gap spark testers. Its not often a coil just gets weak. More often it will start to miss when it warms up until the day it doesn't fire at all. Start with new plugs for sure.
    Other things to look for:
    Rocker arms can pop off but usually make noise. Easy to check.
    Intake gasket may slip out on one side. Usually runs "OK" at high speed but not idle.
    Cam lobe wiped. Unusual failure typically at low hours. Also easy to check.
  8. mowmor

    mowmor LawnSite Member
    Posts: 5

    To all who supplied suggestions on fixing my problem with my 20hp Kohler I would like to say thanks. As it turned out the following things fixed my problem. Replaced the fuel pump and repaired the spark plug lead on the problem cylinder. I would also like to say what a great forum this is for people in the lawn business



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