Lost all hydraulics (loader/hoe/power steering ) the other night while back filling my basement wall. No issues getting a full scoop in the loader, drove over to wall and nothing. No raise, gravity down only. Was able to back away just fine, but I've got nothing from main pump now. Hydraulic fluid is full, no leaks anywhere, 40 hours on rebuilt main pump. I know my next checks are filters and sump screen, and check pressure at main pump test ports. I'm mostly just frustrated because I just dumped $1000 into this machine 40 operating hours ago to replace a bad main pump. And now it's stuck on a jobsite because I can't raise anything off the ground to get it home. At least when I worked on the pump, it was home and in a location it could be easily worked on. Sent from my SCH-I545 using Tapatalk
Pump coupling, not unusual for splines to strip, or the coupler to come apart. Since you have transmission drive, the charge pump is working. Power steering? Could be stroke control valve issue, there is a strainer screen in there that if it plugs will shut the pump down. Pressure control valve could be stuck open also I think, I can't remember exactly how that function between the loader valve and backhoe circuits but I know it dumps to the tranny case at some times.
Update: machine sat on side of jobsite for the past month. Went back to do troubleshooting Saturday and it suddenly had hydraulics. As I was operating, it would lose hydraulics and then slowly gain them back. I'm starting to think I'm suckling air somewhere. Pump coupler is not stripped. I did verify that. Is there a common place that this could suck air from? Sump is full, no visible leaks externally Sent from my SCH-I545 using Tapatalk
I only checked the destroke solenoid as far as making sure it only had power when it was supposed to. I have not checked my priority valve yet. Sent from my SCH-I545 using Tapatalk
It uses the transmission pump to supply the main pump, I would bet anything the sump screen has trash on it. There is a bigger pipe plug under your right foot pedestal that runs left to right, pull that out and screen will be behind it. Gonna need to drain oil first, should be 7-9 gallons. When you start tractor, listen for the pump to hit 2250 psi and it will, move the steering wheel and youll hear it pump again. -Lance
The hydraulic filter is on the left side of the tranny case, not sure on the 310 A if the strainer comes out the right side as 65SIXBANGER says or the left, where the return oil dumps back in. There's a pressure control valve in the hydraulic filter head, the hydraulic oil recirculates and excess flow is dumped back to the tranny case, while you have the suction strainer out and the oil drained, have a look and make sure the spool in the filter head is free to move and the O-ring on the spool is in good shape. If this valve sticks open you lose the charge pressure to the hydraulic pump.
The tractor is running again and I honestly have no idea why. I went out there to test the hydraulic pressure and when I fired the machine up, I grabbed the loader valve and suddenly, the bucket jerked. Reached back, grabbed the boom lever, pulled it back and the boom lifted up slowly, like it was aired up, but reached full stroke. I cycled it a couple times and by the 3rd cycle, it ran perfectly. I cycled all the hydraulics and everything acted like it was aired up. Kept cycling cylinders until they ran smooth and fast again. I've already put 10 hours on the machine and everything is acting just like it did before it quit running. I don't know what went wrong, or what exactly i did to fix it, but it's working and we're all happy again. for now. The sump screen is on the right side of the 310A, behind the auxiliary hydraulic filter. I pulled it already, it was clean.
It kind of helps to have some gauges and a service manual when you get into something intermittent like this. It could be any number of valves getting some little bit of junk stuck in them, or some swollen oring sticking, or whatever. With the gauges you can divide and conquer, you check one pressure and it will tell you to go upstream or downstream so to speak, then you don't go helter skelter around the machine taking stuff apart until it starts working on it's own again and you're no closer to fixing it than before. Of course it's easiest to diagnose when it's not working, so you want to have a gauge ready and know where the first couple of logical places to test are. Or hope it never happens again.
I do have the service manual and have read it extensively since April. After gleaning some knowledge from this forum, I purchased the service manual and was able to use it to diagnose and repair a broken main pump. I am very grateful for a large forum like this where so much information is available to help people diagnose and repair their own equipment. I also bought the pressure gauges to diagnose the system, but it started working the day I was going to test them.