NX5510 - No hydraulics after filter and fluid change

DieselBound · Jan 29, 2023

I've done a fair number of fluid changes and this is the first time I've encountered this. Loader jerks a few inches and that's it. PTO spins, but it doesn't seem very vigorous. Steering isn't happening (no power).

I'd over-filled a bit so I removed fluid to just under full.

Haven't run for more than a couple of minutes (total) for fear of damaging something. All Kioti filters. No issues changing anything. I am using semi-synthetic fluid, spec'd better than Kioti.

How best to work through this?

K5lwq · Jan 29, 2023

When you started the tractor could hear the fluid start to flow? Normally when I change hydraulic fluid I can hear the air purging. I wait till that clears before cycling the valves.

DieselBound · Jan 29, 2023

Kind of sounded like it was dead-heading: was a bit worried so I checked that my levers were all in the neutral position. That sound diminished (no longer?). I've got the fluid level about midway on the stick.

DieselBound · Jan 29, 2023

I suspect the pump lost prime. Not sure of the correct approach to help it regain prime: what hoses to disconnect etc..

K5lwq · Jan 29, 2023

I think fluid level is fine. It should self purge if you let it run for a bit. Can you see the fluid through the fill port? Should see it moving if it is circulating. You can take the line feeding the loader valve off and see if there is flow.

SPYDERLK · Jan 29, 2023

Maybe the filter seal is faulty and leaking enough air to prevent prime.

It doesnt take a lot to foil the suction side of the hydraulic system.

jjeff · Jan 29, 2023

DieselBound said:
I suspect the pump lost prime. Not sure of the correct approach to help it regain prime: what hoses to disconnect etc..

if it's a vertical filter that screws up to the base fill the filter with hydraulic fluid screw it on solved my hydraulic problems when I change fluids in my Kubotas.

DieselBound · Jan 29, 2023

Ran about 5 minutes. No flow seen in the filler port. I can detect pulsations through the return pipe.

Which filter would be the one most likely causing an issue, the hydraulic filter of the transmission filter? jjeff, unfortunately the filters are horizontal. I've never pre-filled before (not on the tractor OR my Kubota).

jjeff · Jan 29, 2023

DieselBound said:
Ran about 5 minutes. No flow seen in the filler port. I can detect pulsations through the return pipe.

Which filter would be the one most likely causing an issue, the hydraulic filter of the transmission filter? jjeff, unfortunately the filters are horizontal. I've never pre-filled before (not on the tractor OR my Kubota).

I've always had to on my vintage relics or Id experience similar problems you describe

K5lwq · Jan 29, 2023

Wonder if you could use a compressor to put some pressure on the tank to force some fluid to the pump?

DieselBound · Jan 29, 2023

I'd read of folks pressurizing. I've got a radiator kit that I might be able to use (has a conical rubber piece for sealing to openings/holes). I would look to pressurize with the engine running, yes? (seems obvious to me but I don't want to make any assumptions)

Is it the gear pump that air locks? I ask because that's where I seem to feel cavitation (and hear it).

K5lwq · Jan 29, 2023

I would do it running or if you can get the suction hose loose I might would get flow to there then tighten it back up and then start the tractor.

DieselBound · Jan 29, 2023

Sadly, I have no clue as to which is the correct "suction line" to loosen up.

I pressurized via my compressor and no go.

Only other "solution" that I've read about is to just let the system sit for many hours (over night?). And if that doesn't work I've burned a bunch of hours. Did not have time budgeted for this... (still have to change coolant)(

K5lwq · Jan 29, 2023

Wow, I can’t believe this is being so difficult. Hopefully letting it sit for awhile works. Sorry for the issues.

DieselBound · Jan 29, 2023

OK, letting things sit for the evening.

I've read of folks being able to regain prime by loosening up output lines*. How does this result in the pump being able to draw in fluid? Fluid is routed from under the pump in which case there's really no way of filling the line going to the pump. I'll note that nowhere do I see any reference to pre-filling filters: not in the operator's manual or in the service manual. If it were that the pump was pushing on air then I'd think that there ought to be a way of opening up/activating a circuit such that the air would be passed along and dumped to the tank.

* Reference: HELP! Branson 7845C hydraulic and motion nonworking...

It's not all that uncommon for a hydraulic pump to lose it's prime when the suction side is opened up for service, particularly if all the fluid and the filter are removed as well. I don't know Branson tractors or how the hydraulics are configured but MOST similar units have engine driven hydraulic and steering pumps. Some are even combined into one pump assembly with two outlets. I don't know how yours is made, but typically the inlets and outlets are flanges or castings bolted to the pump body and sealed to it with O rings. Sometimes the outlet will have a hose attached you can loosen to help bleed the air, but more often it's all steel line from the pump back to next component. If you can access that connection then loosen the mounting bolts two or three turns. With the three point control in the down position, all other valves in neutral, start the engine and let it run for a few seconds. Sometimes that's all it takes to get things going again.

JimR · Jan 30, 2023

I have not had this issue on my NX4510HST. What I have done is changed out the filters first. Then drained all the oil out of the tractor. I refilled the tractor and started up the engine. I let the motor idle for a few minutes then worked the loader. I do not drain the loader when changing the hydraulic fluid.

DieselBound · Jan 30, 2023

Jim, that's exactly how I've always done it! Maybe I was a little too impatient and tried operating stuff too quickly and now I've got a bunch of trapped air. It's a bit on the cold side so that isn't really helping either: I'm waiting to get back to things today but it's under 25 degrees and my shop isn't heated.

I might look to try and get some fluid into the hydraulic filter to see if that'll help: I am tending to think that pulling the filter won't result in a bunch of fluid pouring out because there isn't any because the pump lost prime?

JimR · Jan 30, 2023

DieselBound said:
Jim, that's exactly how I've always done it! Maybe I was a little too impatient and tried operating stuff too quickly and now I've got a bunch of trapped air. It's a bit on the cold side so that isn't really helping either: I'm waiting to get back to things today but it's under 25 degrees and my shop isn't heated.

I might look to try and get some fluid into the hydraulic filter to see if that'll help: I am tending to think that pulling the filter won't result in a bunch of fluid pouring out because there isn't any because the pump lost prime?

The temperature is your problem. Borrow a kerosene torpedo from somebody and heat that garage up. The oil is too thick to flow easily. You could also back your tractor up on a set of ramps which will help the oil flow downhill into the filter and pump.

DieselBound · Jan 30, 2023

I'm above freezing now (36). No change. Loosened the filter and there's plenty of fluid there (not going to pull it off and try to fill it). HST in which case I cannot back it up (or move it).

Thinking that if I were to loosen one of the output pipes from the pump that that might help with priming. Looks to be two 12mm bolts on each pipe. I think I can get to them. Will need to clean everything up real well first.