L4400 HST 3PT/Steering hyd. pump rebuild

[CptJera]

Hi, folks. First timer on the forums.
I've killed the hydraulics on my 'Bota L4400H using the BH90 to dig a septic system. I fear I got the system's hydraulics far too hot. The top boom cylinder even got too hot to touch along with the lines. Backhoe stopped suddenly and now I've got a lovely whining/grinding/spinning noise coming from the pump area at engine shut down.
I've got no hydraulics to the front bucket or backhoe at all, even after an overnight cool down. At least the trans is working so after using a winch to get everything up, I was able to get it into the barn.
I've researched my shop service manual (great investment), user manual and used the Kubota.com Illustrated parts site to find both the pump as well as the exploded parts showing all the components. (T1150-36403 pump assy)
I'm here asking for advice on two things:
1. After checking the relief valve settings and everything else I know of that may have accidentally and/or purposely engaged disabling the hydraulics, is there anything else (levers, buttons, knobs, chants, spells, animal sacrifices) that I should look at? The no steering leads me to believe I've truly killed the pump.
2. If I'm to rebuild the pump -barring any galling or breakage inside the housing- are there any known "gotchas" I should be aware of that are not listed within the service manual itself? Any tips or tricks some of you might have?

One last thing, I recently changed the hydraulic fluid (did not do a flush)after a broken line replacement as well as both filters so contamination should not be a factor. Levels were correct so no cavitation that I'm aware of. Heat is my only suspect.

TIA

Cpt. Jera

 

[CptJera]

One other question:
Buying the pump rebuild components from my local Kubota dealer is out of the question. I wouldn't trust them to order a bag of peanuts. I've found a source in Messick's at what seems a reasonable price, but nowhere else. Suggestions, please?
Thanks.

 

[North Idaho Wolfman]

Very rarely do the pumps or drives go out on these, but it does happen.
Double check your fluid levels, as a low fluid level could cause the pump to cavitate.
Also check your filters as a leak on one of the filters could cause it to suck air and cavitate.
Also check the large suction line for a hole in the steel pipe of the rubber hose.
Then loosen the smaller output line and run the tractor if you get fluid right away then it's a cavitation issue.

 

[CptJera]

Very rarely do the pumps or drives go out on these, but it does happen.
Double check your fluid levels, as a low fluid level could cause the pump to cavitate.
Also check your filters as a leak on one of the filters could cause it to suck air and cavitate.
Also check the large suction line for a hole in the steel pipe of the rubber hose.
Then loosen the smaller output line and run the tractor if you get fluid right away then it's a cavitation issue.

Will do, Wolfman. Thanks. Not my levels tho. Pretty anal about that and going through a full tube of grease prior to every session.

 

[CptJera]

Found the problem. Gears don't mesh that well when they're this slick!

 

[100 td]

Well at least you can buy replacement gear/shaft for it.

 

[CptJera]

Ordered the parts today for drop ship to the farm on Friday. $350 and change.
Got off easy, I think.

 

[100 td]

Hopefully reassembly all works well. Digging a hole shouldn't overheat your hydraulics, just in case there was something else besides your stripped shaft, check your oil cooler isn't clogged.

 

[North Idaho Wolfman]

Check your pressures, very rare to see one strip a shaft like that and high pressure relief setting could do that.

 

[CptJera]

Hopefully reassembly all works well. Digging a hole shouldn't overheat your hydraulics, just in case there was something else besides your stripped shaft, check your oil cooler isn't clogged.

When I felt the heat off of those lines, that's the first thing I checked. Maybe it's me but it sure seems that cooler is undersized for the volume of fluid in that machine.

 

[CptJera]

Okay, gang. I got the parts in and rebuilt the pump taking great care to ensure it went back together correctly. I've now got power to the implements but the pressure is nowhere strong enough to move things normally. The power steering won't work unless the front tires are elevated off the ground and then is extremely stiff.
I've followed the service manual for break-in to the letter. I've drained the system, flushed with 10.6 gallons of new fluid, elevated all tires and turned the tranny for 20 minutes in low range, drained and refilled the fluid and changed filters.
I've dissembled the 3rd function valve and checked for shavings and cleaned thoroughly of anything that might cause it to hang, as this has been an issue in the past.
Still, barely enough pressure to move implements and still no power steering.
Suggestions?
TIA

 

[North Idaho Wolfman]

Check the pressure relief valve.

 

[CptJera]

Check the pressure relief valve.

Looks like I'll need to locate the test gauge required to do this. I'll get busy in the AM. Thanks.

 

[200mph]

I'd consider checking any items downstream of the pump to find out where the metal went from the missing splines.

Did you cut apart the old filters to see how much metal was trapped in them?

 

[CptJera]

Haven't cut them open yet. Probably 2nd thing on agenda tomorrow.
I did open up my 3rd function valve looking for chips and found nothing. Since I've had a heavy welding magnet clamped to the HST side filter since the last change, I'm hopeful I'll find all those chips in there.

 

[100 td]

I'd consider checking any items downstream of the pump to find out where the metal went from the missing splines.

The splines should be in the drive housing, they shouldn't be able to get into the hydraulic circuit. Whether they end up in the engine sump would depend on the drive configuration. (This is an engine driven pump I expect?)

 

[100 td]

Sounds like the pump "could" be cavitating and not picking up fluid? Recheck inlet pipes to pump, as mentioned previously by NIW for suction leaks, as well as the fitting/sealing of the hydraulic suction filter and pipes feeding it.
I would disconnect backhoe and reconnect lines in circuit if this is needed on this model, check hydraulic option valve is set to 3pt if it has one to make sure the pump is not dead headed by any chance. If you can, get a look into the rear hydraulic fill hole, you should see fluid flow? Also make sure any/all remotes are fully centered.

 

[CptJera]

Well, folks. I've discovered my 2nd issue's cause. I have only 500psi because I (am a dumbass for not looking at the H20500 exploded pump view closely enough) installed a "side plate" upside down blocking the gears' lube port during the pump rebuild.

Smoked the plate and the rubber double-ring on the face behind it but the gears and housing appear to be fine. Deformed and cracked the plate quite nicely.

So, another plate and ring ordered which will arrive next Wednesday. Should solve my problem. Meanwhile, I bought a 3000psi gauge, hose and T and installed it at my BH hyd. connection at the rear of the tractor. Spent about $65 but I feel it will be insurance and well worth it. (Will try to post a pic of the assy later)

Now if I can find a place to install a temp gauge transducer in the system and mount a gauge in the dash, I'll be set. Want to ensure I don't overheat or overpressure the system in the future. I'll be able to view the gauge from either the driver's seat or the BH90 operator's position.

If anyone has a suggestion on an install point for the transducer, I'd be grateful.

Thanks, everyone.

 

[L4400 H Don]

Well, folks. I've discovered my 2nd issue's cause. I have only 500psi because I (am a dumbass for not looking at the H20500 exploded pump view closely enough) installed a "side plate" upside down blocking the gears' lube port during the pump rebuild.

Smoked the plate and the rubber double-ring on the face behind it but the gears and housing appear to be fine. Deformed and cracked the plate quite nicely.

So, another plate and ring ordered which will arrive next Wednesday. Should solve my problem. Meanwhile, I bought a 3000psi gauge, hose and T and installed it at my BH hyd. connection at the rear of the tractor. Spent about $65 but I feel it will be insurance and well worth it. (Will try to post a pic of the assy later)

Now if I can find a place to install a temp gauge transducer in the system and mount a gauge in the dash, I'll be set. Want to ensure I don't overheat or overpressure the system in the future. I'll be able to view the gauge from either the driver's seat or the BH90 operator's position.

If anyone has a suggestion on an install point for the transducer, I'd be grateful.

Thanks, everyone.

I am getting ready to replace the Hydro pump on my L4400H.
The differences I’m replacing the pump instead of Seems like $250 is rather cheap price to pay in order to get a new pump vs rebuild.
Did you find any debris in any of the valves that you opened?
I did have some shards of metal like that off of the drillbit on my Hydro filter when I pulled it off and swapped it out and of course the smaller particles.
I have not completely drained my oil, and was wondering if that was a necessity rocket just top it off and rely on the filters were remove any other contaminants. And was wondering if that was a necessity rocket just top it off and rely on the filters were remove any other contaminants. Additionally, did you need any? Did you need any?
Did you need any special adapter for your hydraulic pressure pump gauge?

 

[TheOldHokie]

I am getting ready to replace the Hydro pump on my L4400H.
The differences I’m replacing the pump instead of Seems like $250 is rather cheap price to pay in order to get a new pump vs rebuild.
Did you find any debris in any of the valves that you opened?
I did have some shards of metal like that off of the drillbit on my Hydro filter when I pulled it off and swapped it out and of course the smaller particles.
I have not completely drained my oil, and was wondering if that was a necessity rocket just top it off and rely on the filters were remove any other contaminants. And was wondering if that was a necessity rocket just top it off and rely on the filters were remove any other contaminants. Additionally, did you need any? Did you need any?
Did you need any special adapter for your hydraulic pressure pump gauge?

Why are you replacing the pump?

If you are going to attach a gauge to the pump you need to use a loading valve, tee, and return line. If you dont you will.likely smoke your pump just like the OP smoked his.

Dan