broken spool valve

   / broken spool valve #1  

dirt clod

Gold Member
Joined
Jul 21, 2006
Messages
332
Location
panama city and altha florida
Tractor
Kubota L3300, m5700, case 580se
a few days ago the fel bucket would not curl it felt like it was stuck. Being the quick thinking idiot I decided to try to see if it would move by lowering the bucket to the ground and curling the bucket as I backed up. Thats when the fluid came out of the valve. after this I got off the tractor to check the valve and noticed one of the hoses for the fel had come loose at the quick disconect, I guess this is what the original problem was. Anyhow the spool valve has a small crack on the side and leaks fluid only when curling up. of course I cant buy just the spool houseing I have to by as a complete kit which is pretty pricey. Could this crack be welded? would jb weld work?
 
   / broken spool valve #2  
The valve is probably some type of casting. It may or may not be able to be welded. I would try the JB Weld first. Clean the crack first. If the JB Weld doesn't hold then go to a good welding shop and see what they can do. If they can't help then your only option left is to replace the valve block assembly. I would not attempt this repair myself unless you are an experienced welder who is familiar with the various types of welding including TIG.
 
   / broken spool valve #4  
Actually, depending on the metal composition, spray welding might be the best option. This technique is used by many auto engine repair shops to repair valve seats and other engine block internal problems and by hydraulic repair shops to repair valves, cylinders, rams, pump shafts and couplers.

What hapens is that a special torch heats the base metal then sprays fine metal dust onto the heated area that then melts to form a joint. The weld then can be machined as necessary. My hydraulic repair shop used this technique to rebuild my dozer's hydraulic pump PTO shaft coupler.

Spray welding requires someone who has the equipment and knows what they are doing (it's all technique). You would also have to completely disassemble the valve block.

The first picture is the coupler before and the second picture is the coupler after spray welding and machining. it's better than new.
 

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   / broken spool valve
  • Thread Starter
#5  
I never thought about that. I had no idea a splined shaft could be rebult that way. Did they heat treat that or does the welding itself do that? How much does something like that cost?
 
   / broken spool valve #7  
dirt clod said:
I never thought about that. I had no idea a splined shaft could be rebult that way. Did they heat treat that or does the welding itself do that? How much does something like that cost?
That coupling was never heat treated. It fits into a hardened PTO shaft that is connected directly to the engine. It is intentionally left unhardened so that it will deform and cushion the shock from the snap torque when the engine bogs then revs back up. This is a very common setup on heavy equipment.

A new coupling would have cost me $354 from Komatsu/IH. I paid a lot less to have this one spray welded and re-machined.
 
   / broken spool valve #8  
dirt clod said:
That hose coming off was most likely what coused the problem, right?
Probably.
 
   / broken spool valve
  • Thread Starter
#9  
Thats interesting on the shaft,never would have thought it would be made to shear to protect other parts. Sounds like a exspensive shear pin but i guess it is all relative considering the cost of your machine.

I've gotta say the local dealer is some of the best people to deal with.
The only way they kubota offers the houseing is in a complete valve asem.
But the parts guy told me he just sold a complete kit to a guy that the part that I was needing was not bad on his. He called the guy and told him what I needed and asked if it would be ok to give me his number. He agreed. I called him he was really nice and even offered part for free, I told him I didnt feel right about that. I should be able to pickup part tomorrw for the agreed price of $50. I was looking at $400+.

I still feel pretty stupid that I didnt check for a loose line. I had to clear out some vines the last time I used it was very easy work but I guess one of the vines or small saplings hooked on to the quick release and disconected it.
 
   / broken spool valve #10  
hydraulic valve spools are an extremely close fit, usualy they are fitted at the factory to the housing and thats why they are sold as a unit not individual parts usualy. now thats not to say they wont interchange like you want to do, but i wouldnt place much money on it! for 50 bucks tho i myself would take the gamble and hope for the best, if its too snug and stiff some carefull work with a hone, like a wheel cylinder hone, may make it ok, if its too loose then it will still work but might be a bit leaky, not like pouring out most likely but a nuisance leak that attracts dust and such. like i said, for 50 bucks i would try it before i spent 400.
 
 
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