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Discussion Starter #1
Hello Forum,

Thank all of you for the welcomes. I hope to not wear them out. 2006 4120 PowerReverser open station with 228 hours. Original new purchase... mostly used to finish mow church ball fields and uproot small trees. Ran fine when parked, then bucket began to buck and became sluggish. Changed the spin on filter, cleaned the sump screen, 10 gal of Low-Vis and it ran all functions for about 30 seconds. Inline steering filter was clean. Stopped moving, no bucket, no rockshaft, no PTO and steering is ~binding. Most info says fluid/filters will fix this problem. I did lift the front end to burp steering and prime the system. Normal hydraulic service interval is 400 hours. NO metal in the screen, just aged fluid.

The real clue here is that the hose coupling at the pump manifold partially collapses upon starting the tractor. The 1- 1/2" pipe is clear, the sump is clean, if the filter was clogged the bypass would allow fluid to the pump -- it was free and pops off at 7 PSI resistance and JD parts provided me a replacement filter in case the first was defective.... same thing. Obviously, the pump is not defective since it is asking for more fluid -- evidenced by the collapsing coupling. I did add additional clamps to the hose, but if it was cavitation (sucking air), it would not collapse: it would whine. I know someone in here has heard of or encountered this phantom trouble... I did work the SCV and lift to exhaust all old fluid before change.

Is it possible that the PTO relief valve could vent more fluid than the pump can provide, or am I a victim of airlock and heading the wrong direction? Anyone know of a step-wise bleeding system in this situation? I thought this was self priming and BTW, the case vent is open - no dirt dobbers... I appreciate any input as I am dead-in-the-water where it sits and desperately need before winter.

Thanx in advance - FF
 

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The system should be self bleeding as you suggested, but you can try to turn the PTO on to help get things going if it's electrically operated-that trick works on the little compacts.

Is it part #16 that is collapsing?
 

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Discussion Starter #3
Yes, Kenny,
The hose coupling just below the pump manifold. It will close up as much as the two pipes will let it. There might be an 1" +/- between the two pipes and it will collapse to almost half the diameter. By all rights, it should only be the 2 filters, but it is venting off somewhere or not going somewhere. NO activity at the PTO and I am scared of burning the wet clutch without any pressure back there. That is why I keep thinking that it is dumping faster than the pump can supply. I have a replacement hose but it is just as supple as the one on there. I thought of pulling the manifold, changing the hose while there, and priming the the pipe and the pump and trying again. Someone mentioned that the hose should have a steel coil in it like a lower radiator hose but it does not. I have ordered a 5000 PSI gauge, but that is useless until I get pressure somewhere...
Thx-FF
BTW, I am Bob.
 

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Bob,
My only other thought is the sump screen is in backwards blocking the flow...if thats even possible. I looked in JDParts but only saw the screw on filter-couldn't find a screen (or what typically looks like a screen anyway.
 
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What Changed Since It worked Last?

I wonder if the NEW filter might be suspect? A collapsed hose on the suction side. If the filter were assembled incorrectly or there is something blocking it's inlet would cause the hose to collapse.
The fact that they put a tell-tale viewing port there might make you think it's happened before a lot.
Keep us posted on your progress.
 

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I wonder if the NEW filter might be suspect? A collapsed hose on the suction side. If the filter were assembled incorrectly or there is something blocking it's inlet would cause the hose to collapse.
The fact that they put a tell-tale viewing port there might make you think it's happened before a lot.
Keep us posted on your progress.
He wrote the he tried a second filter:

...it was free and pops off at 7 PSI resistance and JD parts provided me a replacement filter in case the first was defective...
 

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Yes, Kenny,
The hose coupling just below the pump manifold. It will close up as much as the two pipes will let it. There might be an 1" +/- between the two pipes and it will collapse to almost half the diameter. By all rights, it should only be the 2 filters, but it is venting off somewhere or not going somewhere. NO activity at the PTO and I am scared of burning the wet clutch without any pressure back there. That is why I keep thinking that it is dumping faster than the pump can supply. I have a replacement hose but it is just as supple as the one on there. I thought of pulling the manifold, changing the hose while there, and priming the the pipe and the pump and trying again. Someone mentioned that the hose should have a steel coil in it like a lower radiator hose but it does not. I have ordered a 5000 PSI gauge, but that is useless until I get pressure somewhere...
Thx-FF
BTW, I am Bob.
I would not worry about burning up the PTO clutch. It is "living" in oil, and slips until the piston receives hydraulic pressure to squeeze the drive and driven plates together to power the PTO shaft. If it does not get any pressure, it will act as if the PTO has not been engaged.
 

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I would be tempted to try with the sump strainer removed to rule it out.
 

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Discussion Starter #9
Thanks for the reply, Zebrafive,

The screen (stainless mesh) was washed in diesel and blown dry.
There was no metal - only a little gunk - didn't seem enough to
clog the filter. The third filter (steering to PowerReverser) was
clean. Remember 228 hours gentle use.

Also, RE: Kennyd, the screen is symmetrical as seen in the
attachment. There is a flange on each end-- one to the
suction elbow and one to a blank (on my 4120) with a plug
on the other side of the case which fits into a machined hole
in the case. I assume this is for an additional aux attachment.
It comes from the same filtered side.

Lots of rain here the past days. Should clear tomorrow.

-FF

P.S. 30+ years in automotive automatic/standard transmissions,
fuel injection, computer control... now retired medical. Someone
must have had this same issue... I believe my technique solid.
 

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Discussion Starter #11
The FIX !!

Gentlemen, after some bad days, I am back in the saddle again!

Longer story is that about 3 years ago, the caps on the SCV rusted through and sprayed out. Of course, JD only serviced the entire valve. I found caps for the dampers on top but they were not hollow to receive the spring. In a bind, I put the relief valves in and capped without the springs. FEL worked fine - no bucks or jerks. The story here is that I installed 2 gal of the hi-vis to replace the loss. In Florida, operating and ambient temps get well over 100* so I topped off with the hi-vis to compensate. JD says the fluids are miscible, BUT DON'T BELIEVE IT !!

After years of transmission work, I just knew that the suction line collapse had to be filter related, but knowing that I had just changed the spin-on, cleaned the sump screen, and checked the in-line that it should move more than 50 feet/30 seconds. I refused to believe what I had just done did not make the repair and it had to be something else. So seeing consensus in the replies, the unit was re-drained, the suction screen removed and it was clogged again! ... after 30 seconds of running on the fluid change.

I dropped the cover plate on the final drive and there it was... handfuls of goop. It is evident that pouring the 10 gals of lo-vis directly on the crud washed more into the screen. Cleaned the sump and case rear and forward to the screen chamber with fashioned tool and rags down to the bare casting, re-cleaned the screen, filtered and loaded the fluid and it busted off like it should. What a relief - for a moment. We worked it for about 3 hours total pulling 4" - 8" trees and the water pump locked up. I quit asking "what else can go wrong?" when I saw that the curl seals were weeping. NO rest for the weary.

I want to thank everyone for pushing me back to the solution and wish to offer an answer to questions I've seen regarding the elbow at the suction screen. The entire path is rigid and a pain in the a**. I had ordered a replacement suction side hose and installed it on the lower pipe section near the elbow. I measured the pipe with the hose toward the filter head and cut with a sawzall 1/2" behind it and then cut a 1" section off of the pipe on the elbow. This will allow the hose to be pushed forward toward the filter and the elbow removed post haste. Lubing the hose with a film of Vaseline allows it to slide forward after loosening the double clamps on each pipe.
Pictures attached.
These things are engineered for ease of assembly - NOT service and I don't mind the alteration if it saves time and hassle. Next fluid change (likely soon to catch any muck hiding, still) will be a breeze. Hose JD LVU15518 and 4 1-1/2" clamps and a few minutes with the sawzall and a rasp is all it takes. Of course, some purists might balk at this modification, but it saved me a lot of trouble the second time around.

THANX again to all respondents and I will keep an open mind from here on out. My last tractor was a 1942 IH Super C w/live PTO and it was a different animal. So, I hope to live and learn on the GTT forum and hope my "fix" for the stubborn elbow helps someone.

Best to you all-
-Bob
 

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Wow.

Are you sure the "goop" wasn't algae growing in the hydro oil? Mixing low vis and regular Hy-Gard should not be an issue!
 

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Discussion Starter #14
It didn't seem organic. It's like someone squirted a handful of Lithium grease in the case.
It would mush in hand and absorb into a rag without any trace of grit but just discolored.
It was just coagulated and dark, like grease. I know it should mix, but that's what I saw.
Nothing floating in the oil, just the thick muck on the axle pan. Is algae an issue in hydro?
I know in diesel, but oil? 230+ hours. I know these need worked more...
-B
 

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Algae can absolutely grow in hydro oils, do a google search. It seams to start with water/moisture issue though, you may have that from condensation if you don't get your machine up to temp when using it.
 

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I have found Hydraulic Brake Fluid turned to jell inside the master cylinder of s old 70s Dodge Pick up trying to find out why the brakes did not work. Took a while to flush that system!
 

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Discussion Starter #17
Thanks, Kenny.
I had no indication of H2O infiltration.
No white, no foam, no pancake batter.
Initial fluid drain was clear of anything.
I do believe, as painful as it is, that I
should flush the system again just to
flush any crud. Hate that $200 fluid
and the $60 filter- if for nothing. Have
mouths to feed so gotta watch costs.
I still want to contend that something
didn't mesh with the two fluids... there
again, don't pour motor oil into trans
fluid... Type F doesn't mix with Dexron...
I have seen stuff in old diesel, but not
in hydraulic fluid - to date..
 

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Drain all of it out into a White Clean Bucket and let it sit over night and just see what may have settled down or floated. In poorer times I have been known to do this to fluids pouring it thru cloth ect. If it looks like it did when you put it in pour it back in a top off what you did not like. Some times you just have to do what you can afford too do. Radiator fluid is a good one for this suspending a lot of crap while circulating in the engine when you drain it and let it sit overnight. I won't do this to my new JD4044M in fact I tend to change oil more often then needed cause it is cheap to do.


Here is a good article of re/using, cleaning ect about Hydraulic Fluid.https://fluidpowerjournal.com/hydraulic-clean/
 

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Discussion Starter #19
Great article, JD4044M,
Unfortunately, I don't have access to an ISO lab, but what you suggested is exactly what I did.
2- 5 gal white food buckets sat covered overnight and then decanted off all but the very last.
Ran it through funnel/paint filter/cheese cloth back into the leftover new fluid sealed spout pails.
I appreciate your input.
-Bob
 
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