John Deere 329D Flat face o ring hydraulic fittings

[77Ford]

I've had a couple of the flat face o ring hydraulic fittings fail on my skid steer. The first time it was something easy to get to under the cab. This time is was one of the hoses connecting the 2 speed gear box behind the sprocket. I had to pull the track and fight like crazy to replace this one. How do these fail, assuming the fitting is tight there is no movement between the two pieces. It just baffles me, mainly I'm venting because this last one was a huge PITA to repair. I can't imagine taking that to a shop, 600-800 bucks in labor for a dollar O ring?

 

[mg2361]

Was the O-ring cut, or eroded? If it was cut, it was an assembly error at some point. If it was eroded, then there is a misalignment issue with the tubes to the fitting.

 

[77Ford]

It wasn't cut I only found a small imperfection on it. Eroded may be a good term for it. Those lines are clamped wicked tight if the clamps are holding it out of alignment they're going to be that way forever. Maybe I will get another 3000k hours before it fails again. I guess mainly I was venting but curious how they fail, just don't seem like they should once they are tightened up good.