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John Deere 4276T engine knoock

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dannyidp
Join Date: Apr 2014
Posts: 6 GA.
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2014-04-10          190017

Hello.

I am new to this forum so take it easy on me lol.I have a jd 410 with a 4276t engine I completely rebuilt the engine about 5 years ago when I rebuilt the engine I didn't replace the gears on the front,{ cam gear crank gear idler gears ect} I did notice that the backlash was max.The engine has run great up until the other day I have baby-ed this engine with oil changes ect it developed a bad knock yesterday so at this point I have pulled the valve cover and adjusted the valves pulled the oil pan and checked the mains and rod bearings they all looked good,I just can't fig out this loud knocking sound it is very pronounced.I was going to pull the head today I thought i would check with you guys and see if you had any ideas? thanks


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John Deere 4276T engine knoock

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2014-04-10          190021

Dannyidp,

If the main and rod bearings have no excess play, it might be a broken piston, or a wrist pin.

Joel ....

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John Deere 4276T engine knoock

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dannyidp
Join Date: Apr 2014
Posts: 6 GA.
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2014-04-11          190025

Thanks You may have hit the nail on the head, I just have never had A piston problem before but there is a first time for everything time will tell. ....

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John Deere 4276T engine knoock

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kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
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2014-04-11          190030

Danny, first welcome to TP.

I would try to locate the knock or isolate it. Try using a stethoscope or infrared thermometer. Also do not rule out contaminated fuel or injector. If you just fueled up before the knocking began I would look at the fuel very carefully.
Did the exhaust color change? kt ....

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dannyidp
Join Date: Apr 2014
Posts: 6 GA.
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2014-04-11          190035

I have pulled the head off everything looks okay i can take my two thumbs and move the pistons back and forth and can hear the piston hit the sleeve it kinda sounds like the noise i was hearing.these pistons don't have but maybe 300 hours on them could it be a piston? the only thing else that i know of would be gears or cam.man I just dont know right off.I am fixing to pull the oil pan off again. ....

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dannyidp
Join Date: Apr 2014
Posts: 6 GA.
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2014-04-11          190036

OH I think I have isolated it toward the front sounded like it was coming from right behind the water pump which lead me to believe it was the #1 piston but after shaking all the pistons are loose and make that clanging noise. ....

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2014-04-11          190037

Danny,

If you can move the piston back and forth.....that is...left to right.....that's no good at all.

Find yourself a bore gauge at your local tool rental store, or purchase one if you do this type of work frequently.

If your engine has replaceable cylinder sleeves, you might be able to have a new set installed. If not, your engine cylinders may have to be bored. You'll then need a set of over-sized pistons and rings.

Click on the video link below.

Hope this helps.

Joel

....


Link:   Measuring the cylinder bore

 
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John Deere 4276T engine knoock

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dannyidp
Join Date: Apr 2014
Posts: 6 GA.
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2014-04-12          190048

Hey,

After I spun the motor over with out the head on I am almost 100% sure it is the pistons.The only thing now that concerns me is how all of a sudden this was.I would have that i could or would have heard the knocking as it gradually got worst but this was all of a sudden.It sounded like a rod was going to come out of the block but of course it was not a rod.

The only thing different is that i had just made a oil change with rotella T synthetic motor oil I have never used synthetic before and it was thinner than i usually use.I guess stranger things have happened. ....

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2014-04-12          190050

Danny,

Before you get too deep into this project, you might want to check to be sure that you don't have a bad oil pump, or a plugged oil filter. Additionally, you'll want to be sure that all of your oil passages (mains, rods, etc.) are clear.

It's entirely possible that switching to synthetic oil could have produced a good engine scrubbing for you, allowing all of that gunk to plug up your lubricating system.

Hope this helps.

Joel ....

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kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
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2014-04-15          190073

I have used synthetic oil in all my engines with good results. Has been a while since switch an engine but you may be right as the oil is thinner it may allow for noise to transmit better. Joel could also be right it could have cleaned out gunk. Or could have a bad filter. kt ....

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Art White
Join Date: Jan 2000
Posts: 6898 Waterville New York
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2014-04-18          190122


The tolerances on older engines is larger then many of the new engines. The 410 in the owners manual will probably show a 30 weight for summer use. That doesn't mean a 0-30 it means straight thirty.

Don't ask me how many times I've seen this! ....

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jdgreen
Join Date: Jul 2003
Posts: 232 Maryland
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2014-05-28          190388

Did you check for excess play in the balancer shaft bushings? Were they replaced at the time of rebuild? This seems more likely than piston slap with only 300 hours unless you had a four corner seize situation. Did the engine ever stall unexpectedly? Just curious, where did you get your engine rebuild parts? Were they JD original or another brand? ....

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