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  1. #1
    Platinum Member
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    Ontario

    Default BX engine valve clearance adjustment

    My kubota BX 1800 is overdue for an engine valve clearance adjustment. The manual says take it to a dealer however my dealer moved out of town and I don't want to haul the tractor 50 miles to get it done. I this something I can do myself with some instructins from the wise wrench fairies that inhabit this site or should I haul the tractor. Thanks!

  2. #2
    Veteran Member
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    Nov 2003
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    1,338
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    Tombstone Az
    Tractor
    KIOTI LK30

    Default Re: BX engine valve clearance adjustment

    Personaly if it isin't making some sort of valve noise I would just leave it be. I think you may be fixin sometin that ain't broke.

  3. #3
    Platinum Member Grrrr's Avatar
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    Jul 2007
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    800
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    Devon, UK
    Tractor
    John Deere!

    Default Re: BX engine valve clearance adjustment

    Quote Originally Posted by Botabill
    My kubota BX 1800 is overdue for an engine valve clearance adjustment. The manual says take it to a dealer however my dealer moved out of town and I don't want to haul the tractor 50 miles to get it done. I this something I can do myself with some instructins from the wise wrench fairies that inhabit this site or should I haul the tractor. Thanks!
    How do you know it is overdue for one?

    Does it state it in the manual?
    Jake

  4. #4
    Veteran Member Volfandt's Avatar
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    Sep 2004
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    1,879
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    TN
    Tractor
    2004 Kubota BX23, 1966 WheelHorse 856

    Default Re: BX engine valve clearance adjustment

    Even though it is listed as a scheduled maintenance item, I don't know if I'd worry about it unless there was a reason, i.e. loud tapping and/or a noticeable drop in performance.
    That said, if you want to go ahead and check the gap it's not that complicated to do.
    The attachment is for the D905 engine in a BX23 and it might be the same for the 18hp engine.
    Good luck
    Attached Images Attached Images
    BX23 w/60" MMM & thumb.
    1966 Wheelhorse 856, Gear drive.
    1966 Wheelhorse 876, HST drive.
    w/50"sickle mower, 36" RDM, snow/grader plow, Alternator welder.

  5. #5
    Platinum Member
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    Mar 2005
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    Ontario

    Default Re: BX engine valve clearance adjustment

    Thanks for the picture Wolfant. That will help alot. The dealers mechanic will probably be able to tell me if the 1800 is any different than the 23. The reason I want to do the adjustment is not because it is making noise or losing performance but becasue that is what the maintenance schedule suggests. I try to stick with the schedule as closely as possible. Everyone is probably right that this is not neccessary but half the fun of machines (if you get your head into it) is maintaining them. Heck you eventually run out of work to do with them so this gives me more machine though not seat time. Thanks!

  6. #6
    Platinum Member Killer_B's Avatar
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    Sep 2004
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    578
    Location
    Kalamazoo Michigan
    Tractor
    John Deere 3320

    Default Re: BX engine valve clearance adjustment

    How many hours do you have on that tractor?

    Having done countless valve adjustments on my motorcycles, I have seen that (at least on those engines) the clearances will close up over time. It looks like the BX engine has a screw/locknut arrangement, as opposed to the shim under bucket. That makes this a MUCH easier ordeal.

    If your engine is truly up to the hours that call for an adjustment, I say go for it. Make sure the engine is cold. Remove the valve cover. Check the lash as described in the manual, and first see if any are out of spec. If they are, it's a simple adjustment. Loosen the locknut, turn the screw, re-tighten the locknut.

    The last thing I would recommend is before putting it all back together, roll the engine over a few times and then make one final check with the feeler gauges. On my bikes anyway, I have found that from time to time, and for whatever strange reason, a final adjustment is needed.

    As far as "if it aint broke don't fix it," that does not apply to maintenance. As the valve lash closes up, the lifters get QUIETER, not louder. There is a reason that this operation is on the maintenance schedule. When the clearance disappears, the valve tulip no longer contacts the seat, and therefore will not cool. It will then burn up. I have also seen this on my beloved Bavarian motorcycles.

  7. #7
    Veteran Member
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    Sep 2001
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    Kansas
    Tractor
    Kubota L3000DT

    Default Re: BX engine valve clearance adjustment

    Quote Originally Posted by Killer_B
    How many hours do you have on that tractor?

    Having done countless valve adjustments on my motorcycles, I have seen that (at least on those engines) the clearances will close up over time. It looks like the BX engine has a screw/locknut arrangement, as opposed to the shim under bucket. That makes this a MUCH easier ordeal.

    If your engine is truly up to the hours that call for an adjustment, I say go for it. Make sure the engine is cold. Remove the valve cover. Check the lash as described in the manual, and first see if any are out of spec. If they are, it's a simple adjustment. Loosen the locknut, turn the screw, re-tighten the locknut.

    The last thing I would recommend is before putting it all back together, roll the engine over a few times and then make one final check with the feeler gauges. On my bikes anyway, I have found that from time to time, and for whatever strange reason, a final adjustment is needed.

    As far as "if it aint broke don't fix it," that does not apply to maintenance. As the valve lash closes up, the lifters get QUIETER, not louder. There is a reason that this operation is on the maintenance schedule. When the clearance disappears, the valve tulip no longer contacts the seat, and therefore will not cool. It will then burn up. I have also seen this on my beloved Bavarian motorcycles.
    Most of the time, a readjustment is necessary because the lifter was on what is called an acceleration ramp portion of the cam lobe.

    To set valves accurately, you need to have the lifter contacting the cam at a point as nearly opposite the top of the lobe as possible, ie the base circle of the cam. There are various ways to do this but the easiest is this:

    Turn the engine in it's normal direction until the exhaust valve just starts to open. Set the clearance for the intake valve.

    Then rotate the engine, again, in the direction it runs, until the intake valve has just finished closing. Set the clearance for the exhaust valve.

    Repeat for each cylinder.

    This is easy to visualize if you think about the 'mouse ears' silhouette of the intake and exhaust cam lobes as viewed from the end of the cam.
    Meetings: If more than two people are there, at least one's time is being wasted.

  8. #8
    Platinum Member
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    Mar 2005
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    Ontario

    Default Re: BX engine valve clearance adjustment

    More great information. Thanks! To answer Killer's question the tractor has 950 hours on it. The schedule calls for the clearance adjustment at 800 hours. I have been a very bad boy! +

  9. #9
    Veteran Member
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    Sep 2001
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    Kansas
    Tractor
    Kubota L3000DT

    Default Re: BX engine valve clearance adjustment

    Wonder why I have two nearly, but not quite, identical posts in this thread?

    I edited but it saved both copies or something.

    Moderators, feel free to delete one or the other.
    Meetings: If more than two people are there, at least one's time is being wasted.

  10. #10
    Elite Member dfkrug's Avatar
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    NorCal
    Tractor
    05 Kioti CK30HST w/ Prairie Dog backhoe

    Default Re: BX engine valve clearance adjustment

    Quote Originally Posted by Botabill
    More great information. Thanks! To answer Killer's question the tractor has 950 hours on it. The schedule calls for the clearance adjustment at 800 hours. I have been a very bad boy! +
    Your maintenance schedule calls for checking the lash. It will prob
    require no adjustment.

    That said, checking your valve lash is very easy and a good way to
    "bond" with your machine. It is not easy to spin a diesel eng
    to stop precisely at each position called for in your manual. This is
    because there is no easy way to release compression, like in a
    gas engine with spark plugs. So what I do is turn the engine
    with a wrench or the starter motor and check any valves fully
    closed. Then spin or turn again. Repeat until all 6 are marked.
    And heed what cp1969 says about the cam lobe position.

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