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automatic compression release

Discussion in 'Lawn Mowing' started by jeffex, Nov 11, 2003.

  1. jeffex

    jeffex LawnSite Bronze Member
    Messages: 1,933

    On my 8 yr old toro 15 hp kohler command all of the sudden it is a bear to pull the recoil. I was able to start the wb and use it all day by just letting it run. I figured if it was seizing up it wouldn't't have run so good and that would be my answer. When I got home I got on the kohler site and in their shop manual it mentions an ACR. Automatic compression release. It releases compression so you can pull start the motor. Anyone have this experience. This sounds like a trip to the shop. This mower has paid for itself many times over and a new kohler command is around $600 so I may just get a new motor. If the fix is $300 or less I may go that route.
  2. SWD

    SWD LawnSite Senior Member
    Messages: 988

    You shouldn't need a new motor. On the Kohlers, at times the release will become inoperable due to accumulation of debris (typically carbon) . Shouldn't cost more than $100 to get in there and fix it.
  3. Doc Pete

    Doc Pete LawnSite Gold Member
    Messages: 3,469

    Check your valve adjustment. Some of the ACR's are done by lifting the valve. If the valves are out, the exhaust is not opening enough to reduce compression..........
  4. jeffex

    jeffex LawnSite Bronze Member
    Messages: 1,933

    I put transmission fluid in my old van once and ran it for 1hr to clean it out. What are your thoughts on this for the mower?
  5. geogunn

    geogunn LawnSite Gold Member
    from TN
    Messages: 3,010

    I think the ACR on my 14 KAW is out but I don't know.

    it has been out for so long I don't remember when it got "hard" to pull.

    but being a KAW it starts on first pull nearly every time.

    if it doesn't start on the second pull there is something wrong.

    and that is a good thing 'cause I can't pull it many more times!

  6. G-father

    G-father LawnSite Member
    Messages: 174

    It sounds like you have a lot of hours on the motor. If I were you I would not spend 300 to get it fixed. I would say fix it for 100 or less or try to find a new one ( i think you can find one for less than 600).
  7. gramps

    gramps LawnSite Member
    Messages: 241

    First cold day,about 38 degs., the exmark acted the same way. Changing the 30 wts. oil fixed it
  8. Doc Pete

    Doc Pete LawnSite Gold Member
    Messages: 3,469

    As I've mentioned, many motors have a "dimple" on the exhaust cam that pops valve open just a tad to relieve pressure for starting. At "speed" this happens so fast you don't see any difference in performance. However, if the valve clearance is too much (which happens as they wear) the valve won't open and act like an ACR.
    Again, take 10 minutes to adjust the valves....... It could be that simple, and very likely is the problem.
  9. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    There shouldn't be any adjustment on the Kohler valves. Kohler engines use hydraulic lifters. Additionally the Kohler ACR is a mechanical device that only operates under 700 rpm.

    10w30 oil is recommended in Kohler singles when operating below 32 degrees up to 100+ degrees. The use of 10w30 oil should fix your problem. I would try it before taking it in for repair.
  10. jeffex

    jeffex LawnSite Bronze Member
    Messages: 1,933

    I'm going to try the simple first and change the oil. I think I will run an engine flush for a short time and change oil and filter. No time today I'll let you know the result. I would like to get it healed and trade it in on a tiger cub. IT IS my backup mower now.

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