60 lbs compression on kohler with 150 hrs!

Discussion in 'Mechanic and Repair' started by amarino, Apr 9, 2007.

  1. amarino

    amarino LawnSite Member
    from MA
    Posts: 25

    I bought a scag 48" walk behind last spring. Mower is approx 10 yrs old, but had new engine with 10 hrs on it when I bought it. Kohler command pro 15. Now, with approx 100 hrs on it, it takes forever to start (pull start) and has low compression of 60 lbs. Stated smoking a little while running also. Could it be a valve problem, or more likely a piston ring? Dont yell at me, but I didn't change the oil until 80 hrs, and being a new engine I probably should have changed it much sooner. I have read about other kohlers with low hrs having similar problems.

    -Thanks, AL
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    Is the choke fully closed when applied? After you get it running does the engine pull OK?
     
  3. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Considering the engine had 10 hours on it when you bought the mower, I would assume that more than likely it was due it's break-in oil change at that time.

    So the break-in oil was probably ran in it a full 80 hours.
    VERY BAD NEWS THERE!

    All the break-in metals mixed into whatever the break-in oil was spells disaster when ran to 80 hours. I'm surprised it lived to this point. It's likely all chewed up inside from cirulating all those metal shavings in it that long.

    On a new engine, I always change my oil and filter at 5-10 hours, then again at 25, then again at 50, then again at 75, then again at 100. Sometimes at a tighter interval in the early hours if I see a need. After 100 I resume whatever I deem a normal interval for that engine.
     
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    Do you have a Kohler service manual for this engine? Kohler single cylinder engines have a compression release that lowers cylinder pressure by roughly 50% under 700 RPM. That would put your effective pressure up around 120 psi.

    From the Kohler Manual:

    These engines are equipped with an automatic compression release (ACR) mechanism. Because of the ACR mechanism, it is difficult to obtain an accurate compression reading.

    To check the condition of the combustion chamber and related mechanisms, physical inspection and a crankcase vacuum test are recommended.


    Before I would tear into the engine I would drain all of the gas and put fresh gas in it. Then I would pull the bowl off of the carburator and make sure there isn't any water or trash in it. I would also put a new spark plug in it.
     
  5. amarino

    amarino LawnSite Member
    from MA
    Posts: 25

    Thanks for the replies. When it starts, the engine seems to have plenty of power, and runs good except for a little smoke at high rpm. I checked the choke and it looks like its closing fully, but I will check again. Anyone know where I can get the service manual? Its a CV15T engine. Worst case, where can I get a new motor? I cant afford much, so the cheeper the better :)
    Also, when I first got it, it had plenty of compression when starting.
     
  6. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    I don't think you have anything more than a hard start problem. You said it runs good after you get it started so compression is not the issue. Why buy a new engine? How much oil do you add per day/hour?
     
  7. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    I agree with khouse. Before you start looking for a new engine try to find out what is worng, if anything, with your old engine. Those single cylinder Kohlers are tough engines and they last a long time even when abused. What kind and weight oil are you putting in it?

    The service manual can be downloaded from www.kohlerengines.com.
     
  8. amarino

    amarino LawnSite Member
    from MA
    Posts: 25

    Usses about 1 quart per week (15-20 hrs).
     
  9. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    That's a good bit of oil.
    It's getting by somewhere.

    More than likely eat-up internal parts.

    But there is one more simple possiblity.
    The block breather valve

    I don't know if that's an issue with the Kohler 15 or not.
    But I do know a lot of oil can go through just that.
    While the engine is running, it sucks right out and into the airbox/carb.

    Check the airbox/carb for signs of engine oil pulling through.
     
  10. amarino

    amarino LawnSite Member
    from MA
    Posts: 25

    Cleaned the bowl...lots of dirt there! Starts good now but still confussed on the 60lbs of compression.
     

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