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Komatsu PC50uu-1 hydraulic problem

apm

Well-Known Member
Joined
Apr 1, 2011
Messages
171
Location
Northeast Tennessee
Straight 30W non detergent motor oil. That's per the manual. There's been a lot of debate about that, but that is the book's instructions.

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
That's what I thought - I've long since lost my manual - do you recall the quantity? My sight glass was painted over by the Previous Owner and even after scraping the paint off, I can't read it.

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Just wondering about what to use for the hydraulic fluid. I know the manual calls for 30 WT Non detergent, but it seems there have been a lot of changes in the formula for oils since the machine was made back in the 90's. I have some Bobcat Hydraulic/Hydrostatic (40 litres) left over from when I had that machine and I wonder if that would be suitable ?
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Got the oil, filters arrive today - even got a service manual on CD - only problem now is how to take off the cover so I can get at the top filter. :)
 

apm

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Joined
Apr 1, 2011
Messages
171
Location
Northeast Tennessee
It's pretty straight forward. Remove four bolts to take off the sheet metal door, then four bolts in the cover itself. The picture shows it.

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Replaced filters and oil - makes a small difference by noticeable. One further question, I filled the oil level up to the line in the sight glass, without the machine running. When it's running it pulls that level down to the bottom of the glass. Is the proper measurement to be at the line when operating, or when engine is off?
 

apm

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Joined
Apr 1, 2011
Messages
171
Location
Northeast Tennessee
I keep mine at the line with stick extended and boom down all of the way. I don't know if that's right or wrong, but it has always worked for me. The manual doesn't state how to check it that I can find.

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Ok, filters changed, oil level is correct - depending if the machine is pointing uphill or down, boom and buckets work good, turning unloaded is OK, forward and back is good if both steering levers are operated in same direction, can't turn using one lever or by operating turning levers opposite to each other. Putting blade down won't lift the machine, and trying to push anything almost stalls out the engine. I'm guessing something to do with the controls called the spool? that control those functions. My biggest problem - I have no gauges to measure pressure, nor any experience with hydraulics. I do have the service manual on disk, text and diagrams are good, pictures are unreadable.
Maybe it's time to call in the pros - except we don't have any in the little town where I live. :(
 

apm

Well-Known Member
Joined
Apr 1, 2011
Messages
171
Location
Northeast Tennessee
You've got a number of possibilities to check. The tracks and blade are both operated through the swivel joint. You can look it up in your manual. Basically, it's the thing that let's fluid get to all of the operating gear below the house, so that you can swing continuously without wrapping up a bunch of hoses. If it leaks to another section, you won't see any evidence of oil leakage externally, but you won't deliver flow at pressure to your intended system.
If pushing tries to stall the engine, you may have fuel delivery problems in the engine itself and not a hydraulic problem. If you push against an immovable object, it should either spin the tracks, or open the track relief valve. It should not stall the engine.

Look in your manual for the procedure to test leak by in the swivel and see if that's something you feel comfortable with. Otherwise, you may have to find a "traveling" professional.

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Thanks for the info, I've contacted the local Hydraulic guru to come by next week, and we'll use your advice to go forward with over 5K hours I suspect the engine could use a rebuild ! I know a heater broke off in one of the cylinders last year - so I would not be surprised at that Probably a combination of problems

Thanks again !

Greg
 

komatsugreg

Member
Joined
Jul 20, 2017
Messages
24
Location
Creston BC
Finally got the old seat out - need to recover it, this is what I found
The yellow filler tube was a surprise, I don't know what reservoir it fills, I do know there was no oil on the dip stick.
The steering controls go to the 2 valve spooler, the blade control go to the rear one valve spooler, seems like these machine
are like Kinder Chocolates - a different surprise every day. Some weeping around both those spoolers - but not big leaks.
Is the big pump looking thing that sits above the floor - actually the pump?

greg
 

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apm

Well-Known Member
Joined
Apr 1, 2011
Messages
171
Location
Northeast Tennessee
That's your swing gear motor, and the dipstick is for the gear case. It's a hydraulic motor that operates the swing function through a gear reduction. You want to make sure it's got lube.

Greg
 
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