Rebuilt engine knocks after getting hot? Please help

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Glen
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Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
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Re: Rebuilt engine knocks after getting hot? Please help

Postby Glen » Sun Aug 21, 2016 9:23 pm

Hi,
Thanks for writing, now we know what the timing is. If it still knocks, then I would check what the other guys wrote. :)

Bustntruckers
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Zip Code: 21904

Re: Rebuilt engine knocks after getting hot? Please help

Postby Bustntruckers » Mon Aug 22, 2016 6:56 am

if you had aluminium pistons installed that could be your problem,,,i had a rebuild done once on a cub block & had 40 over aluminium pistons installed,,,after installed the eengine & fired it up it would run fine,,,the warmer it got the more it slowed down in rpm's & had a knock...i called the shop & raised hell & they came out & tore it down in my garage,,,come to find out the aluminium pistons are a lil bigger then the cast pistion...they didnt mic the piston & didnt bore the cyclinders out to fit...they honed & honed the cyc & put it back together & ran great..the aluminium pistons swell up when they get hot...timinh has nothing to do with a knocking noise unless its so far advanced it wont start when hot...check your clearance,,bet thats the problem,,,if you run it long enough in time they will hone the cyc themself to fit

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Lee_Petrie
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Tractors Owned: 1957 Cub w/fast hitch restored
1948 Cub w/fast hitch (early style depth control) being restored
Location: Joliet, IL.

Re: Rebuilt engine knocks after getting hot? Please help

Postby Lee_Petrie » Mon Aug 22, 2016 9:51 am

GUARANTEED, "if you run it long enough in time they will hone the cyc themself to fit" , that will NEVER work ! The cylinder wall(s) and the piston skirts will just score , the engine will just have to be rebuilt again ! The clearance is done ONLY at the time the engine is rebuilt , you can't imagine what the piston skirt looks after a cast iron to aluminum seizing, long gouges ( deep scratches ) on the higher "cam-ground" larger diameter on the shirt of the aluminum piston ! Your having piston seizing , and you haven't even made the engine work "hard" yet ?
Lee Petrie, Joliet,IL.

Matt Kirsch
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Re: Rebuilt engine knocks after getting hot? Please help

Postby Matt Kirsch » Mon Aug 22, 2016 3:03 pm

When the engine "locked" did you do any of the troubleshooting for the typical jammed starter problem? Such as, rock the tractor back and forth in 3rd, or try to roll the engine over by hand?

If you didn't replace the ring gear and rebuild the starter with a new drive end, all that is suspect. Your engine may not have been locked up at all.

CraigKennedy
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Re: Rebuilt engine knocks after getting hot? Please help

Postby CraigKennedy » Wed Aug 24, 2016 12:08 pm

Update: guys i just parked the loboy. I drove it a total of about 4 miles at high idle and let it set at hight idle for about 20 minutes. All together a hour and a half of running at high idle and the knock has dissappeared!
Hopefully checking the timing has fixed it
Will try again on my next day off to see if it happens to knock again
Will keep you posted.
Thanks again for everybodys help!


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