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2005 John Deere 3120/ 447 Backhoe, 5' Woods reverse tine tiller, Post hole digger
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Discussion Starter · #1 ·
I tracked everything down to one control valve. The Boom will raise, But when I lower it has no power. I had hydraulic cylinder rebuilt, so I know it is not bypassing seals. I swapped hoses with other control valve and it worked perfect so, I now know it has got to be the 1 control valve. I check the mechanical linkage and all that was fine. Is there a seal kit for control valve? I can not find diagram or video on how to remove the valve. Plus can' find the part or parts, I need to buy. Also how hard is it to replace?

Any help pointing in the right direction would be greatly appreciated.
Chris
 

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Chris, A kit is available from JD, LVA11783 for $42.69.
Do a search for "https://partscatalog.deere.com/" Go there, create an account...free!... and enter your local dealer. Put 447 in model search box and look through results. When you get to your 447 parts list, scroll down to "Valve Section (Boom)" and you'll have a complete breakdown of what's inside.

Looking at parts, I'd think seal kit will only correct external leaks from the spool! Possibly (??) linkage pivots are worn and valve spool simply isn't moving far enough in one direction to give you down pressure. That's about all I can help with! Bob
 

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2005 John Deere 3120/ 447 Backhoe, 5' Woods reverse tine tiller, Post hole digger
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Discussion Starter · #3 ·
Thanks Bob,
I made a call to local John Deere dealer today, They could not even tell me what parts I needed. I asked to speak to mechanic who would be the one who would be working on my tractor if I took it in for repairs. He said he would make sure somebody called me back, Of coarse it is late evening and I have not received a phone call. I will try again tomorrow. I did make one mistake earlier, Its not the boom it is the dipper stick, but the parts should be the same inside. There are not any external leaks. it got to be bypassing inside control valve. I don't mind replacing all the seals inside.

I took the linkage pivots apart pushed and pulled with my hand as far as it would go and it still had problem plus you can adjust the linkage at the locking nut at the top. The guy said I could just buy a new control valve for @ $1, 500, I said no thank you, I just want buy the seals and what ever metal parts I need. It has got to be repairable without replacing the whole thing.
 

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Chris, From parts catalog:

780901

You'll see that item #13 Seal Kit contains item numbers 11 & 12, and simply seals the ends of the spool. With no external leaks, I'd say they're OK as is. The relief valve, Item #1, will be monitoring pressure into the valve and doesn't care about the position of the spool, so i'd say that's OK as is also! Item #2 is a poppet valve. I'm not 100% sure of what it does, but I'm guessing it rides against the spool and the spool activates the poppet. It's possible (???) a groove is worn in the side of the spool and the poppet is not being activated in one direction... and that's a wild possibility/guess! You may be able to rotate your spool 180º and everything will be fine, but I don't know this as fact! Last would be the items under the cap 5, which would be 7,8,9, and 10. They're calling item #9 a cap screw and possibly that's loose? I'm thinking, but not knowing for certain, that this assembly centers your spool when you release the control lever.

Personally, I wouldn't waste the time & $$ to replace #13...no external leaks, it's OK. I'd remove end cap #5 and inspect parts under/inside. Something may (??) be very evident... worn, loose, broken. Last, I would attempt to rotate spool 1/2 turn. Disconnect leakage, move valve slightly back & forth and gently try to rotate spool... do NOT force it! Not knowing EXACTLY how that poppet valve works or where it seals, do NOT remove spool! This may allow poppet to fall into spool bore and entire valve assembly will need to be removed from "stack" in order to get poppet valve back where it belongs.

As a quick note, JD and my dealer wants $3,348 for that complete valve! Talk with your dealer/repairman and see if they can determine the cause...cuz I can't help any more! Bob
 

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2005 John Deere 3120/ 447 Backhoe, 5' Woods reverse tine tiller, Post hole digger
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Discussion Starter · #5 · (Edited)
Bob,
I believe your right, makes sense. I looked at some drawings yesterday, one of those match up with yours. I did find the serial # on the backhoe to make sure. I will try to get some parts ordered and get started with repair soon. So much going on right now with spring arriving.

Sometimes, I get the chance to dig up plants for free around here, when they are going to demo houses.
I had to use my front loader to try and dig yesterday, it was not fun. I miss my backhoe! We have a bunch rock and sticky red clay here. It was bad timming for my backhoe to go down on me.
It took me 6 or 7 hours and a shovel with front loader to dig up some azaleas. It should of taken 1 hour with backhoe. The azaleas have been there for 40 plus years intertwined with other tree roots and up close to the house foundation. The house is being bulldozed down on Wednesday, so It was time sensitive, I get them out of there.

I did score 8 azalea bushes , @ 100 daffodils, @ 100 Irises and @100 sq ft. of Dwarf Mondo Grass. I have been amending the soil at my house for 15 years, so it should not be to hard to replant. It made me sick to think there were going to just destroy the plants, so I decided,I was going to give them a new home.

I will let you know how things turned out when finished. Thanks again for your help.
 

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Hmm, too late now, the (present!) job is done! If you REALLY NEED the backhoe, swap hoses around so "bad" side of valve controls uncurl/dump bucket. You'll seldom, not always, but seldom, need pressure to dump bucket. It may make you crazy until you get used to the new lever arrangement, but, geeze, 6-7 hrs. vs 1 !!!

I'm in Tenn and know all too much about sticky red clay! Yes, please keep me, and others, informed of what you do or find and the final solution. If you look at your original post, you'll see that 116 people have viewed it, so there IS interest! Bob
 

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2005 John Deere 3120/ 447 Backhoe, 5' Woods reverse tine tiller, Post hole digger
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Discussion Starter · #7 ·
I haven't got a chance to try and take care of the backhoe yet. Too many things going on right now. I will post the outcome later when I get around to fixing the repair. Thanks for everybody's help.
 
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