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What's wrong with this Kohler?

Discussion in 'Lawn Mowing' started by Westbrooklawn, Apr 5, 2004.

  1. Westbrooklawn

    Westbrooklawn LawnSite Senior Member
    Messages: 427

    OK - here's the story.....

    I had a problem with overheating, power, missing, etc. with a 20 HP Kohler on my Walker mower. Certified Kohler dealer works on it and finds blown head gasket on one cylinder and blown intake gasket. He replaces those, rebuilds carb, and mower runs fine. After about 100 hours symptoms re-appear......same mechanic replaces gummed up spark plug on cylinder that originally had blown gasket.....can't find anything else wrong. Now about 100 hours later that same cylinder has plug gummed up with oily black carbon to the point it closes the gap on the plug.

    What is causing this? Any ideas???
  2. locutus

    locutus LawnSite Bronze Member
    from NC
    Messages: 1,266

    Sound like you've got oil getting past the rings or valve quides. Does it smoke a lot?
  3. Westbrooklawn

    Westbrooklawn LawnSite Senior Member
    Messages: 427

    It doesn't smoke a lot. It will smoke some times on start up, but it doesn't smoke while running. The motor has 770 hours on it. Would a compression test rule out rings? What would a good pressure reeading be?
  4. Ax Man

    Ax Man LawnSite Senior Member
    Messages: 446

    I think you need to do a leak down test, where you pressurize the cylinder with air and listen for where it is escaping.
    The manual says a standard pressure test won't work because of the compression release built in for starting.
    I did however test mine without knowing that, and got around 100 psi.
  5. barnard

    barnard LawnSite Senior Member
    Messages: 618

    Bad rings/scored or worn cylinder bore are the likely causes of your problem. I 'm sure your using oil,right . It's not the mechanics fault though as he didnt have to tear down that far to replace the gaskets you mentioned. The probable cause is engine overheating be cause of lean air fuel mixture due to intake gasket leaking . As well as unfilter air entering the engine through the intake gasket leak .
  6. Westbrooklawn

    Westbrooklawn LawnSite Senior Member
    Messages: 427

    barnard - I think you have hit the nail on the head. What is the best way to fix this situation..........is an engine rebuild the economical way to go or should I get a new engine with new warranty. The new engine would run around $1300-1400.
  7. GrassFearsMe

    GrassFearsMe LawnSite Senior Member
    Messages: 340

    Well what is the cost of the full rebuild versus a new one, if it is even resonably close go new.
  8. EJK2352

    EJK2352 LawnSite Bronze Member
    Messages: 1,150

    One thing to consider when deciding weather to rebuild or buy new is WARRANTY!!!! Some guy's will give 90 days on a rebuild, some are less and some will offer no warranty at all. If you buy a new complete Kohler Command Pro you will get a full 2 year commercial warranty.
  9. specialtylc

    specialtylc LawnSite Bronze Member
    Messages: 1,656

    Check the E.G.R. system.
  10. Westbrooklawn

    Westbrooklawn LawnSite Senior Member
    Messages: 427

    What is the E. G. R. system?

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