Kohler CH25S Bent Push Rods

Discussion in 'Lawn Mowing' started by Homecutter, Nov 28, 2004.

  1. Homecutter

    Homecutter LawnSite Member
    from Orlando
    Messages: 26

    :help: I recently purchased a used Yazoo Kees Zmax 52" ZTR mower with a Kohler CH25S Spec#68561 to mow my own 1 acre of Floritam more quickly. The engine had 860 hours on it and ran fine for the first 50 hours. I would always check the oil before every use out of paranoia. Well, after about 51 hours of use it started running rough and would spit a little white smoke (not real thick) at start-up. It got to the point where it would no longer idle and would only run at MAX throttle. I continued to run it this way for about 6 more hours when it SUDDENLY started pinging to loosing power BIGTIME. I barely made it back into the garage with the deck OFF. The thing crept along like a turtle.

    I pulled the valve covers and all 4 Push Rods are bent. Two are so bent they match the curve of a banana. I have begun disassembly of the motor. Have yet to open the crankcase. My guess is slipped timing which allowed the pistons to hit the valves?? Might be a broken tooth on the crank or cam shaft? The tops of the piston are evenly coated with black soot and there are no markes in the soot that support the piston hitting a valve. I would have expected to see evidence on a piston if it struck a valve. Not sure though. Anyway this will be my first small engine rebuild experience.

    I have read every post on this forum about the CH25S and saw none with this same problem. Ticking lifters, blown head gaskets and poor oil flow seem to be the main complaints.

    Any suggestion would be appreciated.

  2. Green Care

    Green Care LawnSite Senior Member
    Messages: 530

    I only can tell you that kohler has a great website with trouble shooting guide any everything else you may need.

    Good luck.
  3. burnandreturn

    burnandreturn LawnSite Senior Member
    Male, from Germany
    Messages: 303

    Kohler had a problem with the rocker arm assembly in that motor.
  4. Travis Followell

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

    You can download a repair manual for that engine off of Kohlers website or you can buy one for about $20 but you will definately need one.
  5. Homecutter

    Homecutter LawnSite Member
    from Orlando
    Messages: 26

    Thanks for the replies. I have yet to delve into the teardown. I will post my findings soon. My motivation is currently low due to slow lawn growth and Holiday activities.
  6. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    What weight oil are you using?

  7. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    don't tear it down it has not slipped time if it did it would be blown up
    sounds like you do have some trouble with the rocker arms.it could also be the
    lifters kohler has always had some problems with those they now have 3 that they use on that engine be sure to order by spec# .
    one thing you did not mention is the service on that engine have you? and if so was it done fully.was it power tuned at 500 hr's?10w30 motor oil? all these
    things will play a part in a break down.
    i normally don't have any problems like this anymore years ago kohler engines had many problems with the valve train but that has since been took care of
    one other question how old is it???
  8. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    I agree with the above. Don't tear the engine down. The lifters can absolutely cause the pushrods to bend. Been there, fixed that.

    Replace all 4 lifters and pushrods. Kohler has a new lifter that is supposed to fix these problems. Make sure the salesperson orders the new lifters.

    NAPA also sells a lifter removal tool that makes this job a breeze.
  9. Homecutter

    Homecutter LawnSite Member
    from Orlando
    Messages: 26

    After much delay my hands are quite dirty. Since removing the engine I decided to restore (repaint) my Yazoo Z-Max. I bought all new deck rollers, stickers, grips, belts etc. I'll be using Devoe (ICI) industrial coating Safety Red for paint. Painted my well tanks blue years ago and its tough as nails.

    About the engine... I had decide to buy a new engine to match the restored mower instead of trying to rebuild it myself. I did not want to spend >$400 on parts on an engine with 900 hours. Not to mention I was questioning my skills. However after reading your response I amd going to replace the rockers, lifters and pushrods and see what happens.

    I was running Penzoil 10W-30 when it died.

    "was it power tuned at 500 hr's? Sorry, I don't know what this means.

    I beleive the engine was mfg in 1998.

    You guys like Combat Robots?? Check out my website teamotown.com. I can build robots but I'm not sure I can rebuild a Kohler CH25!
  10. Brianslawn

    Brianslawn LawnSite Silver Member
    Messages: 2,002

    kohler engines are easy to rebuild. i was talking to a rep the other day and bent push rods and some cam problems have been somewhat common. if your valves look good then just try new rods and maybe lifters. torque head bolts do x pattern to 15 ft lbs, then again to 30 ft lbs. rocker arms to 7-9 ft lbs. be careful, the threads in the head for the rocker arm bolts strip out easy on used heads. heli coil can fix if it happens. get the online mannuals from kohler.

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