JD310A Hydraulic leak on side of transmission - help please
I have a John Deere 310A backhoe/loader that I am wrestling with. There is a "block" on the side of the transmission that keeps leaking on me no matter what I do. Changed an Oring a while back (#7 in parts diagram) and it stopped, but it started again and I can't seem to fix it.
There are 2 "ports" in this part which mount flush to the side of the transmission - which I believe is the pressure control valve. The issue I am having is one seems to be triangular - but when I look online at the diagram it says it is circular and calls for an O-ring. Does anyone happen to know if the 310A had a special gasket here and later on they changed the part and the new one uses an Oring? Is there a part I can still get for this one - or am I seeing things wrong in this tight spot? Any assistance would be appreciated. I am trying to avoid taking the whole part out as it is a tight spot. The "port in question is #8 on the part diagram and is partially visible in the bottom left on the second picture.
Welcome to GTT
Have you checked pressure control valve housing to be sure that mating surface is flat/level?
The mating service looks flat/level and never appears to have been removed from what I can tell. It's this one port that mounts flush to the side of the transmission with no matching port in the transmission that seems to be leaking. I'm not a tractor mechanic by any means but rebuilt engines for cars and the like and you dont normally see two metal surfaces mounting together with a port without a gasket of some sort. Trying to head out the door now to take another look before it gets dark - but man it gets dark early now.
The second "port" in question is definitely square/triangl-ish, not a circle - and has no recess for an oring or gasket. I am a little baffled. I dont see how a gasket could even go here - but I don't see how two metal mating surfaces would not leak. Also there is no port in the transmission to match - so I imagine that is there for another model or just for the space to "bleed out." This is not the hole with the pressure control part. That is a circle and an Oring fits perfectly. I have tried torquing it down many times in different patterns and it ranges from one thin like of a leak to 2-3 separate lines of fluid leaking out. I had fixed this part leaking before but it didn't last all that long. Maybe a month and started leaking again and all I did was change the one Oring.
At the moment I am just baffled. Any advice is good advice in my book.