[AT] Kubota M5700 noise

[Mike M]

When you had it apart, did you check all the piston,ring and bearing
clearances?

Mike M


On 4/6/2020 11:35 AM, Dave Maynard wrote:
> No sleeves in this engine. Someone had this engine apart before and #5
> had a new piston and rod and bearings. The seller said it was his
> father's tractor since new and never been apart....he lied! There was
> more RTV on oil pan than you could imagine and obviously that piston
> and rod and bearings had been replaced and I thought they had been
> chasing the noise. Unless there was some other reason, but dont know.
>      My friend and mechanic help has a Jacobson mower he's is
> rebuilding that has a 4 cylinder version of this motor that appears
> identical except the number of cyl's. He found the rod to be the same
> except it a tweak shorter by an almost immeasurable amount, maybe .005
> or .010. Part number is almost the same except last digit and now I'm
> wondering if that could be someone's mistake. Would shorter rod cause
> preignition? By the way, there is no part number on the rods so they
> would have to be accurately measured.
>      It's going to be a bit before I can get this back apart again,
> but hoping to have this fixed in time to plow.
>
> Dave
>
> On Mon, Apr 6, 2020, 9:08 AM Cecil Bearden <crbearden at copper.net
> <mailto:crbearden at copper.net>> wrote:
>
>     That was one of my thoughts, but my experience has been that the
>     liner movement was a double "thud" once on down stroke and once on
>     upstroke.
>     Cecil
>
>     On 4/6/2020 1:12 AM, k7jdj at aol.com <mailto:k7jdj at aol.com> wrote:
>>     Cylinder liner loose.  Don't know if this engine even has
>>     cylinder liners if it does and that liner is moving you would get
>>     click. Did you look carefully at the head when you had it off and
>>     look for any sign of head distress?
>>     I would do a compression check as well.
>>
>>     Gary
>>
>>     Renton, WA.
>>
>>
>>     -----Original Message-----
>>     From: Roger Moffat <rogerkiwi at gmail.com> <mailto:rogerkiwi at gmail.com>
>>     To: Antique Tractor Email Discussion Group
>>     <at at lists.antique-tractor.com> <mailto:at at lists.antique-tractor.com>
>>     Sent: Sun, Apr 5, 2020 7:43 pm
>>     Subject: Re: [AT] Kubota M5700 noise
>>
>>
>>
>>>     On Apr 5, 2020, at 9:59 PM, Dave Maynard
>>>     <dave at themaplehillfarm.com <mailto:dave at themaplehillfarm.com>>
>>>     wrote:
>>>
>>>     Have cracked injector lines one at a time, and it gets quieter on #5
>>
>>     But only on #5?
>>
>>     When you crack the others the engine misses, but the noise remains?
>>
>>     I wonder if something about cylinder 5 is somehow different so
>>     that the compression is higher, and so it’s igniting
>>     (pre-igniting) too much before top dead centre in just that cylinder?
>>
>>     Eg #5 piston slightly higher than the other 4?
>>
>>     Roger
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