Komatsu PC50uu-1 hydraulic problem

[apm]

Hello, I am brand new to the site and a new owner of 2 Komatsu PC50uu-1 excavators. Both have been sitting for years. One runs and the other needs some help and possibly parts if the previous owner doesn't find everything. May end up being a parts machine, but I'd like to get both going! I was hoping to get some general info regarding these machines.

1st, Would someone be willing to share the PDF manuals discussed earlier in this post?
2nd, Any help regarding where you have had luck getting parts. Local, foreign, online. Are dealers helpful with these grey market machines? Any scrap yards parting them out?

Hopefully I am not hijacking this thread, but it seems to be a general thread for PC50uu's

Thanks

They are fairly simple machines to work on. No electronics, fixed displacement (three stage) gear pumps, Komatsu engines. Dealer can find most parts, but John's right, very expensive. Ebay has some parts. Final drives may not be available as exact replacements, the -1 used Hy-Dash drives. Tracks readily available. Hoses use Komatsu spec fittings, not available at some hydraulic shops but available to order.
Pretty good, solid workhorses, but slow compared to more modern machines.

Greg

 

[jeeperjake]

A few more PC50uu-1 questions. I need to order a manual, but want to make sure I get the right one. Anyone have a link to the one(s) that are known to be good?

I also want to go pick up all of the filters needed, but don't have the numbers and would rather not take all of mine off to take to NAPA. Anyone know the part numbers for engine oil, hydraulic oil, fuel, and air filters? Any others than I missed?

Thanks

 

[John C.]

I would suggest you contact your dealer for ID, price and availability before spending a lot of time chasing through the internet. You might be surprised at what they can do for you.

 

[Michaelnashville]

OK, I tried this post in the main excavator forum and got no response. Maybe it should be here, instead?

I've got a 1993 Komatsu PC50UU-1 gray market machine. I've got the pdf manual for it. It's got a hydraulic problem that I've been unable to figure out.

This machine is a direct hydraulic machine, no electronics, solenoids, etc. in the hydraulic circuit. I believe it uses a gear pump. The pump is 3 stage and is supposedly brand new (installed by the previous owner). There are two control valves that operate all of the functions. One is a 6 spool valve and one is a 3 spool valve. The first two stages of the pump feed the 6 spool valve, and all functions seem to work as they should. The third stage of the pump feeds the 3 spool valve. this valve controls the blade, the swing motor and the rapid travel function. The blade is weak as well as the swing (slow). The rapid travel functions. I hooked a hydraulic gauge into the line from the pump to the 3 spool valve. There is a test plug there for that purpose. When operating the blade or the swing against the stop pin, the pressure never gets over 1500 psi. Relief is supposed to be about 3100 psi.

I assume I'm bypassing oil either in the pump or the 3 spool valve. The pump is supposed to be brand new. I can hold a function open or against the stop until pressure comes up to 1500 and I'd expect heat to build if I was bypassing oil somewhere. The pump does not seem to get overly hot, nor the valve.

I've swapped out the relief valve from the 6 spool valve (same part number) into the 3 spool valve, and it made no difference. I've had the 3 spool valve out of the machine and totally disassembled and cleaned it. I found nothing wrong, nothing broken, no excessive clearances, etc. There is also a suction and safety valve on the 3 spool that I disassembled and cleaned. It appeared to be fine but I've got no way of testing or swapping that one.

What would you try next?

Thanks,
Greg

Check your fast travel pedal adjustment.my machine will creap left and blade work very close and travel unevenly if the fast travel pedal is not seated all the way .my machine sets alot so the controls have seized up numerous times.sintge rods get bent and throw off the stroke.

 

[Michaelnashville]

A few more PC50uu-1 questions. I need to order a manual, but want to make sure I get the right one. Anyone have a link to the one(s) that are known to be good?

I also want to go pick up all of the filters needed, but don't have the numbers and would rather not take all of mine off to take to NAPA. Anyone know the part numbers for engine oil, hydraulic oil, fuel, and air filters? Any others than I missed?

Thanks

I'll look and see,I use napa proselect filters..so much cheaper than the oem.

 

[obas2070]

Hi Greg,
I tried to get my local Komatsu dealer to do the same thing for me but they weren't willing to, basically saying, "It wasn't designed for this kind of setup and we don't want to take responsiblity for ruining ". Could you post photos of your hose/pipe setup and give details on the diverter valve (manufacturer, part number, etc)? Do you know if you can run a breaker using your setup?

 

[obas2070]

Just bought this PC50UU-1, company buys them in Japan, ships them to Vietnam, where they’re allegedly disassembled and rebuilt and shipped to the west coast. Can’t pic up a log with the thumb, guessing hydraulic issue as discussed here.

It’s gorgeous on the outside, still going through internals, confirming what was and wasn’t rebuilt. Compression test in the motor produced 425, 350 & 380, a deviation of 22%, well over the 10% ideal range. It’s going back for a fresh motor or my money back and probably some hydraulic work if the thumbs any indication.

 

[apm]

I'm very sorry, I sold the machine a couple of years ago.

Greg