I have a 2005 New Holland LB75B backhoe. I have a continuing hydraulic leak from the hose that attaches to the output of the hydraulic pump. It utilizes an o-ring to seal pressure. I have replaced the o-ring and there is no leakage. However after about 4 hours of operation, the hose at the fitting will leak profusely. When I remove the fitting, the o-ring is distorted, cut and sometimes split through the horizontal plane. One time the o-ring must have extruded from the recess area because the o-ring had a small "pinched" surface on the outer diameter. I have purchased a new hose and have ensured all sealing surfaces are clean and smooth. The o-ring per the parts manual is 0.625" x 0.070", nitrile with a Duro value of 90. When you order the o-ring from New Holland it is specified as 0.614" x 0.070", nitrile and Duro value of 90. The replacement o-ring fits securely in the recess area of the fitting. I try to not turn the hose when tightening the hose coupling nut. I thought possibly the hose was moving after contacting the o-ring during tightening the coupling nut and the movement was destructive to the o-ring. Last replacement I greatly tightened the coupling nut and made note of the hose position. Same result and the hose did not appear to move. Excessive leaking from the top and bottom of the coupling nut. I also tried to just apply a snug tight torque on the coupling nut and it only lasted a few minutes before leaking. This leak has me puzzled and I am out of ideas. I still believe the problem is from the o-ring and crush (compression) orientation.
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