Troubleshooting hydraulic leak on Deere CT322

[ColdBlackWind]

While changing tracks on the machine I developed a catastrophic leak in the hyd system. We were bumping the left drive to aid in getting new track over front idler pulley. I heard a pop and the hyd oil flooded out from underneath the machine. After raising the cab and removing sheet metal to expose pump, foot valves and hoses I have yet to find the source of the leak. I was going to put a couple of gallons of oil in the system and bump the motor over with a remote start button but I am not sure about how the park brake and permissives work. Under normal conditions after starting all controls are locked out until park brake is released. Is that a bypass in the pump? No controls were being operated when it emptied the system. What would be under constant pressure with everything in “neutral” to allow it to pump out all the hyd oil?

 

[mg2361]

The whole hydraulic and hydrostatic system is under pressure (charge pressure, roughly 300 psi) when the engine is running and all functions are in neutral.

 

[ColdBlackWind]

mg2361 I appreciate your answers to my posts. I thought cranking the motor with cab up was my best bet to find leak. The machine is in the woods and it is muddy where it sits. We have had record rain for August. I can’t see a clear path to getting it off the ground so I was heeding your warning about cranking it to try and find the leak. That seemed like the best way to find it. I pulled the guards for the drive motors so I could see the hoses and fittings there. My back up plan was to lower cab, start and stop engine then raise the cab as quickly as possible to see if I can tell where it is coming from.

 

[ColdBlackWind]

Ok. After weeks of head scratching and monsoons I am now really confused. I tried putting low air pressure in the hydraulic reservoir hoping to hear a leak. Nothing. I put 3 gallons of hyd oil back in it and tried the air again. Nothing. I decided to lower the cab back down and start it momentarily then raise it back up to try and find leak. I started it. It built up pressure. No leaks so I raised the boom all the way up. No leaks. I am getting ready to adjust track I just installed and move the machine to the barn. Wondering if 3 gallons is enough so if there is a leak related to drive motors it won’t puke the full 5 gallon capacity out? Also, is there any type of high pressure relief that could open under system over pressure??

 

[ColdBlackWind]

Ok. Found it. Left side drive motor hose. I couldn’t feel it as it is in a loop and the hole was on the bottom of the hose where it sits against the pan. It is pressed against the pan fairly hard and I am sure the failure mode was chafing. Not an easy fix but I am happy to be able to get on with the repair.

 

[ColdBlackWind]

Thought I would share this. Got the hose off this morning. No problem actually. Had a new hose made up locally. I told the folks there what my problem was around the hose bearing against the steel floor pan. They sold me some neat hose guards to try. The hose was also showing signs of wear where it lays between the two other hoses that run to the drive motor. We put a sleeve on it to help that. I have attached pics of old hose and new hardware.