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720 John Deere Diesel Grinding/Growling Noise

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Foxquads
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PostPosted: Tue May 29, 2007 4:58 pm    Post subject: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Hello All;
Yesterday I was baling hay with my baby: 720 John Deere Diesel, when all of a sudden she started making a terrific, loud grinding/growling noise!!! At first I thought a piece of clutch facing had come off and become lodged somewhere. Today I pulled the clutch completely out and the noise is still there...It does seem as though there was a slight "wobble" to the pulley that I had not noticed before... I pulled the cover off the flywheel and did notice that there is a bit of up and down play to it and there is a bit of an oil leak..
...Have my crank bearings gone? Can I replace the ends (only) without much trouble?
This has the pony starter...
Oil pressure stayed the same as before... This tractor is a later one...
Thanks for your input!!!
Louis

 
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dds-inc
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PostPosted: Tue May 29, 2007 5:58 pm    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

UH OH! I fear that your flywheel has gotten loose. what happens is that the hammering of the diesel engine breaks the flywheel GRADUALLY looser and looser until it knocks. I want you to inspect your flywheel and see if it is moving up and down.

 
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Foxquads
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PostPosted: Tue May 29, 2007 6:45 pm    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Well, the flywheel isn"t loose; other than being able to move it about 1/32" up and down, crankshaft and all...Remember that this noise started all at once...??????? Somewhat like a "stuck starter" but the pony starter drive was not engaged...
Thanks!
Any more suggestions?
Louis


 
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jimtNV
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PostPosted: Tue May 29, 2007 6:57 pm    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

you could have spun the bearings. im not sure if it is the mains or the rods. this looks rather scary.

 
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Foxquads
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PostPosted: Wed May 30, 2007 3:20 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

OUCH!!!!!!!!!!

 
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f-I-T
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PostPosted: Wed May 30, 2007 7:00 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

I don't think that you necessarily have a bearing problem. If a two-cylinder diesel has a bearing start to drag (it was fairly typical of the center bearing on the diesels) the engine generally just drags down to a halt and can't be turned.

Is it noisy engine running, pulley stopped? Noisy engine running, pulley turning, pto lever disengaged?

Could it be a pto related noise? You could have a first reduction or pto gear/bearing problem. Does the noise go away if the pulley is removed and the engione run for just a quick test?

Look the pulley over closely. You might want to remove the driver plate and the facings since I think eventually you'll want to check if the bearing in there decided to gaul up and shake apart, and look the bushing over, too. It will likely need service anyway. At each point that you tear it down, go back and check if you can see if the noise/rattle is gone, reduced, or at least has been located.

Go to the flywheel side and see if you notice any metal dust that can indicate the flywheel splines disintegrating. Check the bolts. It's not uncommon for one or both bolts to stretch and leave the flywheel loose or in a bind. If you have to go in further, I recommend that you replace the bolts on reassembly. Now check for excessive endplay, like .020" or more. Excess endplay will cause them to hammer, and if the fiber washer gets pouned to dust, you can be left with noise from .060" or more play and hammering on the thrust plate. This occurs more freqently on the 70D's and early 720D's.

If you have excessive play, remove the flywheel, then the trust cover and have a look around. At this point with the pulley and the flywheel removed, put a dial indicator on the flywheel top side of the crank, set it to "0" and lift the crank using a pipe over the end, or even with a gentle lift from a floor jack. Check the other end as well and you'll have a pretty good gross check of the bearing clearances, not exact, but you'll be in the ballpark.

By the time you get to this point, you should know if you have to go inside. You might have a bearing problem, so don't forget about the center bearing. But I think you have some work to do before you need to think about crank removal and rework. My two cents.

Frank

 

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DSK
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PostPosted: Wed May 30, 2007 9:02 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

I agree with Frank's post where he mentions a possible PTO and/or first reduction bearing problem, thats where I'd start looking. Drain the oil out of the first reduction housing, if it's a late 720 it will have a rectangular cover fastened with 2 bolts on the bottom of the cover for this purpose. If you have pieces of bearing or any other iron in the oil you've probably found your problem. Even if the oil looks normal I'd still pull the pulley and first reduction cover from the tractor and check things out. Like Frank said it's a good time to clean, lube and replace worn parts in the pulley at this time.

 
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Foxquads
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PostPosted: Wed May 30, 2007 11:07 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Thanks!
Yes the noise is there anytime the engine is running: pto in/out, clutch in/out, and in gear or out...
I put a prybar under the flywheel and there is quite a bit of "up/down" movement, perhaps .035 to .050 ...
( I'm a tool & diemaker, so I feel comfortable saying this...
I'm in the process of taking the flywheel off...The last person has apparently put it on with JB weld so it has been a pain to say the least...I had to cut the 'stamped nut' off... The flywheel is just about ready to come off - got to get the engine lift hooked up to it now.
As yet I have not seen any 'shavings' etc except a piece of clutch disc or two but after removing the clutch and all the plates from the pulley the noise still exists...
...Please continue to post suggestions and I will let you all know what I find!
Thanks so much!
Louis

 
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Foxquads
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PostPosted: Wed May 30, 2007 11:12 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

If this is the problem would it be noisy anytime the engine is running no matter whether pto is engaged or not (?) If so, I'll stop and look there.
Thanks!
Louis

 
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Foxquads
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PostPosted: Wed May 30, 2007 11:18 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Also when I took the cover off the flywheel there is a bit of oil that has puddled inside and leaked on the floor...No metal or anything unusual though so far...

 
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F-I-T
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PostPosted: Wed May 30, 2007 11:41 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

This can happen over time if the thrust cover oil seal gets old. There should be a little dimple at the bottom of the cover to allow a drizzle of accumulated oil to drip out, but sometimes it gets some dirt or chaff over the hole and that clogs it up, so some oil gets "stored".

No metal dust of chips is a good thing.

Frank

 

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PostPosted: Wed May 30, 2007 11:47 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Yes and no. If it is PTO related and the noise is present engaged or not, it would be the pto gear/bearings that is turned by the crank at all times. If it comes and goes when you engage the pto shift in/out lever (the one next to the clutch pedal, not the live pto clutch lever), it would be the driven gear train from the sliding gear rearward.

 
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F-I-T
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PostPosted: Wed May 30, 2007 12:02 pm    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

>>>the noise is there anytime the engine is running: pto in/out, clutch in/out, and in gear or out...I put a prybar under the flywheel and there is quite a bit of "up/down" movement, perhaps .035 to .050 ...>>>

No matter what it is, that is a lot of bearing play given that it ought to be in the range of .007 or so. Tell me what sort of hours on the tractor since its last major overhaul. Play like that is going to have to be taken care of eventually even if it is not the cause of this noise.

>>>I'm in the process of taking the flywheel off...The last person has apparently put it on with JB weld so it has been a pain to say the least...>>>

THAT really makes me feel good about the condition of your engine. Let's ponder this. "Should I fix it right, or put some epoxy glue on the crank splines so the next guy can deal with it".....If I were you I would not look forward to a quick diagnosis and repair. If you really like this tractor, I bet you will find much more out of service limit problems as you go deeper, based on the previous owner's level of repair. How long have you been running this engine under real work conditions?

>>>I had to cut the 'stamped nut' off...>>>

Those can be a bit pricey (just a warning), so I would have recommended that you heat it with nothing more than propane to soften the goo and grab it with the pipe wrench, or my favorite, my 36" Channel-Lock pliers. They alays come off for me that way. It is only used to push and hold the flyhweel inward until you get the bolts clamped down on to the crank shaft.

>>>the flywheel is just about ready to come off - got to get the engine lift hooked up to it now.
As yet I have not seen any 'shavings' etc except a piece of clutch disc or two but after removing the clutch and all the plates from the pulley the noise still exists...>>>

It could even be something as innocuous as a tin oil shield inside the first reduction cover that is rubbing. Before you go so far as to render the engine inoperable, try a piece of garden hose as a stethoscope to try and figure out which side the noise is coming from. You know there is also a tin shield that is located behind the flywheel to seal the pony area and flywheel cover. No chance that it got bent and is rubbing? That can sound pretty awful.

One last thing, when you say same noise pto in or out, do you mean whether the pto lever is engaged or out? You can only put that in gear when the engine is stopped but you can "kick " them out while they are running for a test. This is different than the live pto clutch lever by the battery box.

What EXACTLY were you doing the moment that the noise began? and that could be "Just driving along, running the baler,minding my own business".....

Frank

 

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Foxquads
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PostPosted: Wed May 30, 2007 5:45 pm    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

Thanks, Frank!!!
All has not been lost even if I find the noise elsewhere as you are correct - part of the felt seal is missing and the seal (rubber one) has seen better days!!!
It has been a 'heckufa' day getting the flywheel off with all that JB weld on it...So much infact that it has actually squeezed into the minute space between the flywheel and the thrust plate...I'm still trying to pick the JB weld out of the splines so I can get the thrust plate off...
Louis

 
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Foxquads
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PostPosted: Thu May 31, 2007 3:15 am    Post subject: Re: 720 John Deere Diesel Grinding/Growling Noise Reply to specific post Reply with quote

"What EXACTLY were you doing the moment that the noise began? and that could be "Just driving along, running the baler,minding my own business".....

Frank "

Good morning Frank;
I was running a square baler...Was running in 1st gear...Had baled over a hundred bales...I shifted into 2nd and "it" happened shortly after that...
...Before that, though, I thought I'd heard a "pop" or "crack" occasionally...I am almost deaf, so I thought it was my imagination; OR that it came from the baler...????
Thanks!
LOuis

 

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