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Discussion Starter · #1 ·
I'm having a little trouble with the "bucket lift" circuit on the loader. The "bucket curl" seems to work fine, with good speed and pressure. I think the problem is with the 2 spool control valve. Sometimes when the valve is in the position to lift the bucket, I can hear the pressure getting bypassed and the bucket drops. Other times the bucket will lift, but no pressure to do any work. My questions:

-Can these old valves be rebuilt or am I better off getting a new replacement?

-Based on my complaints, do you think the valve is the problem? Am I on the right track?

Thanks as always for your suggestions.
 

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Are you sure that the valve linkage is consistently operating the valve. It seems odd that the valve would hold sometimes and not others. I'd check the linkage for wear, bent parts etc. I hope it's something simple!
 

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If the piston ring in one of the lifting cylinders are leaking you will have the problem as you describe.

To check hold the control valve in the lift position for a while (maybe 5 - 10 min) and feel on the cylinders with your hand. If one of the cylinders becomes warm you have a leaking piston ring.

Hope you understand.
 

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Discussion Starter · #5 ·
So far it looks as if you are all correct. I will start with a rebuild of one lift cylinder that I've identified as being weak (with the help of "case closed'). We did as Per suggested and noticed that the left cylinder was not acting right. Couldn't tell if it was warmer because its on the same side as the exhaust.

Valve linkage also needs a tune up. Former owner used a large cotter key at the pivot point for the levers on the control. I'll improve that with the correct size bolt. Case closed just rebuilt his control today with good results and a few dollars worth of seals. He is going to add a filter for the loader hydraulics soon. I may do the same. Sounds like it may be worth the effort.
 

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Make sure you change all 4 o rings in the cylinder. One is hidden and you can't see it until you take the big nut off at the end of the piston.

Ask me how I know. It drove me nuts trying to fix a leak until I talked to someone who rebuilds and sells Johnson Loaders.

I found every size O ring needed at Sears Hardware. Only cost a few bucks for all of them.
 

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Discussion Starter · #7 ·
Thanks NJ Ken. That helps a lot, I am going over to a hydraulic repair shop in the morning. I have the cylinder disassembled (discovering worn out, non pliable seals) and I know just the nut you are referring to. I tried Per's method again and sure enough, if you run the system long enough with the control lever in the lift position (and the bucket not moving) you will notice one cylinder getting noticeably hotter than the other.

How tight should a cylinder with new seals feel? On this one, if you extend the ram all the way out and then hold the cylinder vertically, the ram will immediately fall. No resistance at all. I think with new seals it will be a lot stiffer.
 
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