Help with Hydraulic Cylinder Repairs

   / Help with Hydraulic Cylinder Repairs #1  

philgreen

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Joined
Apr 13, 2009
Messages
32
New to the forum, this place is great!

I have a JD 855 with a 70A loader. The loader is tired with all the cylinders leaking at various rates. The guy I bought it from had two seal kits for the bucket cylinders, so I jumped in and rebuilt them.

The first cylinder came apart OK, but there was a small burr on it where the snap ring keeps the ram in the cylinder. Not knowing much, I just rebuilt it and carefully pushed it all back together. Big surprise, it started leaking a week later.

So, I took the other cylinder over to a hydraulic repair shop. They took it apart and cleaned away the burr. I also carefully cleaned up the piston that had a bit of a burr on it too. Put it back together and really big surprise, it started leaking about a week later. WTF!!!

Can anybody offer any advice. Seems I might have to redo everything and am not willing to throw good money after bad. I am running low viscosity hydraulic oil from JD. Please help.

Thanks,
Phil
 
   / Help with Hydraulic Cylinder Repairs #3  
philgreen,

Were those the correct kits? Did the repair shop install the kit? Just take it apart and see if you did anything wrong, and again check for burs.

Some of the parts have to go on correctly. The lip on the seals for instance.
 
   / Help with Hydraulic Cylinder Repairs
  • Thread Starter
#5  
Thanks for the replys,

Yes, I wet them down with hydraulic oil prior to assembly and I used the correct parts from the correct kit, per the instructions. The JD instructions were pretty good, with pictures and drawings to make sure things go together the right way and with the right parts.

I know why the first cylinder leaked, I didn't do a good job. What has me stumped is why the second cylinder is leaking? JJ is right, I will have to take them down for a look see. Before I do, I hope somebody else on the forum has been in a similar situation and posts a reply.

P
 
   / Help with Hydraulic Cylinder Repairs #6  
Those JD cylinder bores can be a real bear to get to seal. Check the o-rings when you disassemble it. Tther should be two of them, a round one and a rectangular one. The round one goes towards the fluid. The other one is a back-up and goes away from the fluid. Check the back-up, one side will be curved, the curve goes towards the o-ring. You also might have torn the o-ring when you installed it. Good luck.
Andy
 
   / Help with Hydraulic Cylinder Repairs #7  
Phil,

Did you use it very much after you installed the new set of o-rings. It just might need a little time, to setup and for the o-rings to flex/expand, etc. Some rubber/seals expand in some types of fluid. Is the leak a drop or two, or a stream?
 
   / Help with Hydraulic Cylinder Repairs
  • Thread Starter
#8  
Andy,

I'm pretty sure we installed the rings in the correct order. I had no idea however, that there was a concave orientation to the backup seal. I will check it. One question, if I tear it apart shouldn't I put in all new seals in any case???

JJ,

Very good point. I have not used it to any great degree. I am seeing a couple of drips from both cylinders. (Just enough to piss me off!) I will wait a few weeks to see if it clears up.

I wondered if using low viscosity oil might be giving me trouble? Any comments??

Thanks,
Phil
 
   / Help with Hydraulic Cylinder Repairs #9  
Phil,

Did you have to clean up any burs, rust, etc? If you have to smooth off some things. Do not sand /rub up and down the cyl rod, you will leave scratches that may run past the seale/o-rings.. Sand around the cylinder rod. If the repair is longer that the seal area, you will probably have trouble later on. A drip here and there. Another thing, is it leaking at rest or when in operation/ full pressure.

http://www.maxxhyd.com/hydraulicseals.htm
 
   / Help with Hydraulic Cylinder Repairs #10  
I have seen units develop leaks when switching over to a lower viscosity oil, but these cylinders should seal up regardless. The o-rings should not leak and time won't make them leak less.
I would install new o-rings but the other seals should be fine. The bores may need to be honed. Inspect where the o-rings ride very carefully for anything.
 
 
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