Backhoe Hydraulic repair

bowman316

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So I have a new Holland backhoe that we boiled the hydraulic fluid in. It had a clogged hydraulic filter, that was causing the fluid to overheat; So as a result, all of the hydraulic cylinders were leaking.
I just changed the seals in the front 4 cylinders, but now I need to move the machine. Should I change the old fluid out now, and put new fluid in before hooking up the front cylinders, or should I use the old fluid in the freshly rebuilt cylinders? Will mixing in any of the old, previously boiled fluid hurt the new fluid? How would I ensure the whole system is empty of the old fluid before adding the new stuff in?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I would change the fluid. if your seals started leaking due to temp, you exceeded 250 degrees
 

Grub54891

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I would change the fluid, and filter, twice to get all of the questionable fluid out as much as possible.
 

MTboatguy

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It needs to be purged and changed before moving it, you have already changed the seals, no reason to push the contaminated fluid up against those new seals, fluid is cheap compared to replacing seals with all of the labor involved, keep them clean and they will last a good long while.
 

rbh

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I would be concerned about how much damage to the pump was done by cavitation due to lack of fluid.
If the fluid smells burnt its going to need a flush, you said you are replacing the upper packing and scrappers? how about the rams O-rings? they are probably cooked as well.
Time for a tear down I am thinking,
Its going to be a PITA but you do not want to do a half way job or it will come back to haunt you latter..
 

bowman316

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The seals on the piston ram's all seemed fine, the only place it was leaking was around the gland seal that goes around the rod. And for the wire seals, it was leaking around where the locking wire comes out the side of the cylinder.

I bought the whole seal kit thou, so I changed all of the seals. Why would there ever be fluid past the piston? Seems to me it should just pump the fluid behind the piston, to move it forward and back. Or maybe it pumps fluid on both sides of the piston, depending on which direction you want the rod to go?
 

bowman316

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Do you REALLY have to change the hydraulic fiilter, considering it was just changed a month ago? I guess its worth the extra 80 bucks.
 

rbh

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All fluid and filters should be changed if it got that burnt- (you could send out the fluid to be analyzed if you want)
Does New Holland use the frame as a storage area for fluid??
 

bowman316

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Fluid inside the frame? I don't think so. I know its a 30 Gallon system. Not sure if that means just the tank is 30 gallons, or if that's counting all of the fluid in the cylinders too.

Today I put 5 Gallons of fresh fluid in, just to be able to lift up the rear digger arm, to get it to where I could work on it. Used a tractor to pick up the front bucket to move forward to get out of the barn. Now I have all the rear cylinders off, and have the arm supported with 2 4x4's. I'm a little worried that cranking on the cylinder glands might cause the cribbing to fall out. I am using the rear bucket attachment point as an anchor point to crank on the cylinder glands.
 
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