Need a hydraulic guru !

[poconoguy17]

I have been working on my B600DT for a few weeks now and have had a weird air entrapment issue I can't seem to figure out.

I have drained and flushed 5x, the last time I found some dark/oil at the base of the reservoir and suctioned that out and cleaned the screens again.

All hoses replaced with new, all tight and no leaks.

Today I cut off a section from the pump side of the return line from the reservoir as it was chewed/soft/leaking.

Chewed up pump side supply line:

After about 5 mins of running after refilling this is what I see in the fill cap/breather port.

I cycled the loader and bucket quite a bit in hopes of bleeding out any pockets. When drained I had all cylinders extended , drained and retracted to compress and drive out any fluid.

Under lower/moderate RPM it operates smoothly and quiet, but under high RPM it squeels.

 

[hagrid]

Did you replace the entire length of suction line? The remainder can be collapsed and cavitating your pump at higher volume demand.

 

[poconoguy17]

Did you replace the entire length of suction line? The remainder can be collapsed and cavitating your pump at higher volume demand.

I have not , I just cut they gnarly end off and reconnected. Tomorrow I will head to NAPA and see If they have a replacement hose for the entire run.

Short of the line itself still being problematic, I guess the only thing left is the pump itself?

 

[Pau7220]

Definitely replace it. Do not use heater / coolant hose. Anyone who makes hydraulic hoses should have the suction / low pressure hose you need. NAPA etc.
If you strike out, I'm sure Northeast Hydraulics in Dickson City has it. Monday of course.

 

[Russell King]

Did you clean the screen filter that may be installed inside the transmission case? I don’t have a clue if your tractor has one but if you don’t have a spin on filter there is a good chance you have a tube mesh screen that the fluid is sucked through into the pump feed line.
On my old L185 it is opposite side of tractor than the feed line to the pump behind a domed cover with two bolts holding it on. I recall seeing other posts where a similar screen screws into the feed line boss like a big bolt.

 

[poconoguy17]

Definitely replace it. Do not use heater / coolant hose. Anyone who makes hydraulic hoses should have the suction / low pressure hose you need. NAPA etc.
If you strike out, I'm sure Northeast Hydraulics in Dickson City has it. Monday of course.

Thank you for the advice. I will look for it tomorrow!

 

[poconoguy17]

Did you clean the screen filter that may be installed inside the transmission case? I don’t have a clue if your tractor has one but if you don’t have a spin on filter there is a good chance you have a tube mesh screen that the fluid is sucked through into the pump feed line.
On my old L185 it is opposite side of tractor than the feed line to the pump behind a domed cover with two bolts holding it on. I recall seeing other posts where a similar screen screws into the feed line boss like a big bolt.

The loader is self contained and doesn't share anything with the trans. I cleaned the screen-mesh in the loader several times, only the first time was dirty. Thank you for the feedback and help.

 

[redfernclan]

I'm guessing sucking air and cavitating. May have sucked some air because of bad suction line and then took the pump out. I don't know how to check that except disassemble pump and inspect or replace. I have seen bad pumps that are cavitating heat up quick, like after two minutes of idling they are getting warm to the touch. If that is so, I would say you need a new pump.

 

[Pau7220]

like after two minutes of idling they are getting warm to the touch. If that is so, I would say you need a new pump.

I would say if it doesn't get warm to the touch you probably have a broken pump drive or shaft. They're always moving fluid and will get warm. The only ways for air to get in there and foam the fluid is on the suction side, body seals, cracked body, or shaft seals.

 

[North Idaho Wolfman]

What fluid are you running in it?
And what you're describing sounds is a pressure relief valve issue.

 

[poconoguy17]

What fluid are you running in it?
And what you're describing sounds is a pressure relief valve issue.

I was running Kubota UDT but last flush I only had access to Walmart Universal Tractor Fluid , which is what is in there now.

Pressure relief valve issue? Could you explain as to what I should be looking for or adjusting?

 

[poconoguy17]

I would say if it doesn't get warm to the touch you probably have a broken pump drive or shaft. They're always moving fluid and will get warm. The only ways for air to get in there and foam the fluid is on the suction side, body seals, cracked body, or shaft seals.

It def gets warm alright. Not so hot that it burns but warm enough you wouldnt want to keep a hold on it for too long. Also I get squealing at full RPM using the loader but if I back off the RPM a little its smooth and quiet.

 

[poconoguy17]

Replaced the suction line to the pump and used NAPA brand generic hydraulic fluid. Not sure which or both it was but the FEL operates quietly and smoothly now. The viscosity seems thinner and I believe its a 10W fluid, but all operates much much better then it did previously. No foaming out the breather, cavitation or squealing, noises.

 

[hagrid]

Aha!

 

[Pau7220]

It's amazing how much trouble one rotten (literally) little hose can cause.

 

[North Idaho Wolfman]

I was going to ask what fluid you had in it, as I've seen cheap (heavy fluid) do that.
Glad to hear you sot it licked!

 

[poconoguy17]

It's amazing how muck trouble one rotten (literally) little hose can cause.

Agreed. Lots of headaches !

 

[poconoguy17]

I was going to ask what fluid you had in it, as I've seen cheap (heavy fluid) do that.
Glad to hear you sot it licked!

Never would have thought that a UTF that was thicker would cause so much hassle lol. But the loader operates so smoothly now and has (perceived better lift) .

 

[Henro]

Never would have thought that a UTF that was thicker would cause so much hassle lol. But the loader operates so smoothly now and has (perceived better lift) .

Cannot help but ask: learned you lesson yet?

Seems like the message is to get rid of the aftermarket hydraulic fluid and put UDT or SUDT back in there. You don't change it that often. I would do it for the peace of mind if it were me...

 

[Pau7220]

I believe that hose allowing air to be sucked in was more the issue. It was definitely porous and possibly collapsing.