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  1. #1

    Default Help diagnosing problem with Kohler M20QS

    I have a Bolens tractor with a Kohler M20QS (20 horse) engine. The problem is that the engine has low compression and is low on power. It will also use oil when under a heavy load. I have a 48" deck and it will stall the engine if I mow through grass that is too high.

    I took it to a local dealer and they did their leakdown tests and some other tests that I can't remember and they said the only thing they could find is the tractor is low on compression and has a clicking sound that comes and goes. They don't know why the compression is low.

    They say the next step is to tear it apart and check it out which will cost at least $1000.

    I was wondering if anyone had a second or third opinion before I do anything stupid.

    Thanks,
    Jim

  2. #2
    Elite Member
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    Default Re: Help diagnosing problem with Kohler M20QS

    How are the maintenance items, clean oil, good crankcase vent, is engine sludged up? Did they say what psi the compression actually was, valve clearances, plugged muffler, old age?

  3. #3
    Member armyof1's Avatar
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    Mar 2004
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    Shibaura SP1540

    Default Re: Help diagnosing problem with Kohler M20QS

    jaghobbies,

    I would say if you took it to the dealer and had it tested did they say it might be the rings. Does it smoke when under load more than normal. Did you do a wet compression test on the engine. From my stand point at this time it is the rings. But there is also the heads that need to be checked clicking my be a valve not closing all the way. I would also check other dealer 1000.00 for just tear down is high to me. Valve, head gasget, bad head or rings. http://www.jointsystems.com/kohler_specials.htm

    Check this link a new M20QS is only a 1079.00 at this price I get some local school kid shop class to put in a new engine before I pay 1000.00 just to look at it and tear it down Hope this help. Sam

  4. #4

    Default Re: Help diagnosing problem with Kohler M20QS

    The engine oil has been changed every 25 hours or so. No sludge in the engine. I haven't checked the vent yet. They just said the compression was under spec. I'm going to recheck it when I get it back.

    I was thinking is was probably too much valve clearance. I thought this would cause a clicking and low compression. I'm going to check that out too when I get it back.

    Not sure what tests they performed but they didn't think it was the rings. Didn't really say what they thought it was.

    Thanks for the help,
    Jim

  5. #5
    Member armyof1's Avatar
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    Shibaura SP1540

    Default Re: Help diagnosing problem with Kohler M20QS

    come to think of it I had a race car engine do the same changed the fram oil filter it came backe to life. I do not use fram any more Sam

  6. #6
    Platinum Member Lazy's Avatar
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    ford 1920 w/fel and bh, case 470, allis chalmers B 1937, JD 450 track loader, Case vac, 3 cub cadets ford lgt 125, Kubota 2230/60 inch mower.1948 farmall cub 1953 farmall cub

    Default Re: Help diagnosing problem with Kohler M20QS

    Hi
    you can download a service manual from kohler

    http://www.kohlerengines.com/service_manuals.html

    and check with the folks at this forum, a lot of kohler experts hang out here

    http://www.ihcubcadet.com/forum/mess...tml?1073885406

    Charlie.



  7. #7

    Join Date
    Aug 2002
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    North East CT
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    2003 Kubota BX-22

    Default Re: Help diagnosing problem with Kohler M20QS

    You might have good luck finding an answer at the Kohler Engine Club at Yahoo Groups. There are over 350 members over there that seem to know their Kohler engines.... http://groups.yahoo.com/group/Kohler_Engine_Club/

  8. #8

    Default Re: Help diagnosing problem with Kohler M20QS

    I'll try some of the other forums but here are the results of the tests:

    Compression 75-80 psi
    Manometer reading 20"
    Leakdown - middle of good reading

    Jim

  9. #9
    Veteran Member Rowski's Avatar
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    North Central Vermont, Jay Peak Area
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    2004 New Holland TN70DA with 32LC loader, 2000 New Holland 2120 with Curtis cab, 7309 loader

    Default Re: Help diagnosing problem with Kohler M20QS

    Seems like if they did a leak down test they could find out what general area the leak down is coming from.

    Air hissing in the carb/intake--> intake valve
    Air hissing in the muffler--> exhaust valve
    Air hissing from the crankcase vent--> rings

    Again this just getts you in the general direction.

    Of course the cylinder needs to be at TDC.

    $1000 to find out why a 20hp engine has low compression...I'm in the wrong business [img]/forums/images/graemlins/blush.gif[/img]!

  10. #10

    Join Date
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    2003 Kubota BX-22

    Default Re: Help diagnosing problem with Kohler M20QS

    </font><font color="blue" class="small">( ......................
    They say the next step is to tear it apart and check it out which will cost at least $1000.

    I was wondering if anyone had a second or third opinion before I do anything stupid.

    Thanks,
    Jim )</font>

    I am almost certain that they were referring to tearing it down and rebuilding the engine, not just tearing it down to inspect it. I believe this is a case of the owner of the engine, not comprehending the entire conversation as to costs. This is also a common problem, people saying one thing and the person hearing the words, misses some of the important details. If the shop did in fact, figure $1000 to tear down the engine for inspection, I would say that they were not qualified to do the work, because it would take them too long just to do the inspection. I am assuming that their hourly rate to be about $50 and it won't take 20 hours to tear down that engine. Possibly two hours would be more likely, and I am being generous with that figure. I suggest that you go back to the shop and question them further.

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