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
i am not the technician,we are the parts supplier for Komatsu excavator.I am not able to answer your questions,hope other ones can help you.
Check your cycle times for the swing and blade. Also check your other cycle times (travel, boom, ect.)? Does the blade or swing seem to drift? What is your pilot pressure at? Komatsu seems to like to put little screens in all their pilot fittings, there should be a screen on the outlet of your pilot pump or at its first valve in, as well as screens in all your pilot control pressure in lines. Theres also usually screens in the pilot lines into the control valve. Does your swing motor have reliefs on it? If the swing motor has reliefs that could be your low swing pressure (the swing pressure is suppose to be lower than main pressure though)
Thanks, Gary for the reply. There is no pilot system on this machine. It's just straight hydraulics with spool valve control. There are two spool valves, a 3 spool and a 6 spool. All of the functions resulting from the 6 spool valve seem to be fine. All of the functions from the 3 spool valve are weak, ie; the blade and swing. I'm trying to determine if I have a pump problem or a valve problem. One stage of the pump (3 stage) feeds the 3 spool valve. The pressure to that valve won't go over 1500 psi. By the book, should be about 3100 psi. Greg
The cycle times for the swing and blade are within the book spec. They just don't have any power. The blade won't lift the machine and the swing will barely move with a load. The swing appears to get worse as the oil heats up. May be dealing with two problems, hydraulic system and swing motor. Greg
Good cycle times suggest a good pump. A bad gear pump will generally still build good pressure, but slow cycle times. Sounds like your safety valve is weak. I dont have a pc50uu-1 book (my books start from -2). Does the swing drift at all? Can you push of the stick and turn the house? Does the blade drift? When you are reading the 1500psi, is it when the swing is stalled or the blade, or either, both dirrections?
Check your pressure on the 6 spool bank,if thats where it should be,try swapping the pressure lines on the 2 valve banks if possible.If the problem switches valve banks,then the pump is bad,if it stays the same,the relief is weak.
The swing doesn't seem to drift at all. The swing feels normal with no load, but slows down as the oil heats up and is weak. The blade does not drift. If I lift the front with the boom, then put the blade down, it will hold the machine up after I've lifted the boom. The 1500 psi reading is when either the blade or the swing is stalled. capnkel, the 3rd stage of the pump that feeds the 3 spool valve is smaller and lower flow than the other two stages. I can't physically swap the hoses without having new hoses made. Is it worth a try even though it's lower flow? thanks guys for the input, I'm not having much luck, yet. Greg
I think its worth a shot swapping lines around,a few adaptors should be easy to adapt the different hose sizes.It would give you a much better idea where the trouble lies.Check the pressures on all 3 pumps before swapping hoses around.The machine does not need to be throttled up just to see how the pressures compare,so the higher flow pump going into the lower flow valve wont hurt a thing.
Hey there I know this problem with the pc50uu-1 was posted 6 months ago I am having the same problem. I've re built the hydraulic motor so I know it's not that, I've worked through the whole machine and now I'm up to the swivel motor I'm wondering if I've got a broken seal which is by passing the hydraulic oil? Can someone please help me cheers
Greg its Tony here I'm having the same problem with my pc50uu-1 how did you solve the issue I'm at my wits end cheers mate.
Hi Tony, I'm still working on it. I just got a set of test hoses made to be able to swap the pump stages between valves. Hope to get a chance to try it this weekend. I'll post if I come up with an answer. Greg
OK, so I finally got a chance to swap the pump stages to the control valves. The stage that normally operates the blade and the swing, I moved to the arm and the right hand drive motor. The problem moved. Previously the blade and swing were very weak, now they're strong as they can be. The blade will pop the machine right up off the ground. The swing is faster and snappier than I've ever seen it. But the arm is weak and the right hand drive motor barely turns the track, so I guess that means one stage of the pump is bad? I can't think of any other cause, there are no electrics or electronics on the pumps or valves, just straight hydraulic. Anybody have any input? Thanks, Greg
Sounds like the pump is bad. Maybe the gears are spinning on the shafts
Sounds like that section of the pump is worn out.You should be able to replace just that section if you can find the parts.You would likely need a new set of gears,gear housing,wear plates and a seal kit.If you happen to be lucky enought to have a pump that the gear section can be flipped in,that will get you back most of you power.Its not a hard job to do at all.A couple pics of the pump might help us identify it.If its a common brand,you may not need to buy from a dealer at their inflated pricing.
It's a Kayaba pump. I got it apart this weekend and it really doesn't look bad at all to me. I took it to my Komatsu dealer this afternoon and he looked at the parts and said "you better look somewhere else for your problem, there's nothing wrong with this pump". The only other thing I can think to check is some kind of restriction on the suction side. Maybe collapsed hose or something. Anybody else got any ideas of things to check? Thanks, Greg
Make sure there is nothing between the pump output and the weak valve section.maybe you missed a valve somewhere?Are there any valves built into that pump?Some have what looks like just a plug,but contain flow or relief valves built into the pump housing.If the problem swiched sides by switching pumps,that pretty much eliminates any issues with the control valve.One thing you could try is putting a spare valve inline hooked to the weak pump section,and see if your pressure is ok right at the pump.Pictures sure would be a big help.
It's pretty much just a "plain Jane" pump, no valves or reliefs. It's fixed displacement gear pump. I'll see if I can figure out the picture thing. The gear is made as all one piece, can't be slipping on the shaft. Thanks, Greg
This should be a link to a copy of the pump parts drawing, showing the third stage that I'm having trouble with. http://komatsupartsbook.com/#t=p&p=/root/25146/6960854/6960969/6960972 Thanks, Greg
to add to the mystery, the Komatsu dealer put the pump on their test stand and all three stages checked out good. I think that's good news, but I sure don't know where to go from here. Thanks, Greg
If the pump is checking out as good,it should build the same pressure 3100 psi ,assuming the relief valves are set the same,when hooked up to either the 6 spool section,or 3 spool section.Id hook it to the 6 spool,check psi,then swap reliefs again and check psi.If everything is pretty close on the psi,and its not going past 1500 psi on the 3 spool valve,there has to be some internal leakage in that section of valves.
OK, so I put it all back together on Saturday and it all runs like a champ. Strong on all functions and full pressure from all stages of the pump. The only thing I did was remove and disassemble the pump, and when I put it back together, I changed the hydraulic suction strainer and filter. I guess it's possible that we "tweaked" something in the pump that was originally assembled incorrectly, but that's a stretch. What I'm thinking was happening was that the suction strainer on the outflow of the hydraulic tank was clogged to the point of not allowing enough oil through for all 3 stages of the pump to see enough flow. The first two stages are larger, therefore higher suction, and the third stage in line (the weak one) must have been starved for oil. All I know for sure is it's sure working well and I'm grateful. Thanks for all the advice and input. Greg
Just to update and thank everyone again for the help, I've used this thing all summer on several good sized projects and everything continues to work great. Still plenty of power. I added a hydraulic thumb. That's the biggest improvement yet. Thanks, Greg
APM how did you add your hydraulic thumb? did you go off of the off set cylinder?
I put a 12 volt diverter valve in the boom offset cylinder circuit. If I flip a toggle switch one way, it powers the boom offset, flip it the other way (default position) it powers the thumb. Works slick. Greg
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?
I'll try to get some pictures in a day or two. I'm not sure about running a breaker, there may not be enough flow for it to run effectively. The Komatsu dealer is technically correct that it was not designed as an auxiliary circuit and won't contain the normal components of a typical auxiliary. But, the boom offset only gets used on my machine once in a blue moon, so why not take advantage of it for a thumb that gets used every time I get on the machine. I did plumb in a crossover relief valve while I was at it. All of the hydraulic components came from Surplus Center, including hoses and fittings. Greg
Thanks. I look forward to seeing your pics. Regarding the flow rate, there are two control valve blocks for the PC50-UU. The flow rate for the offset control valve block is higher than that of the control block that would contain the auxiliary circuit. The Komatsu mechanic said that rather than not being enough, there is a risk of it being too much. I checked into this before and the offset flow rate fit within the specs that my breaker listed. Unfortunately I can't find those specs any more...
If this works, here are some pictures. Greg
OK, in the post above, the first picture shows the SPST toggle switch installed next to the throttle. This actuates the diverter valve in the picture immediately below it to select either the thumb cylinder or the offset cylinder. In the off position it defaults to the thumb cylinder. The original lines to the offset cylinder go to the "in" ports on the diverter valve. From there, new lines run to the offset cylinder and the thumb. In this post you can see a picture of the crossover relief valve intended to keep the thumb from overpowering the bucket. Greg
Could you provide more pics in the areas from the pipes on the boom to the connections on the offset cylinder (the general area shown in the attached pic)? I understand the connections but I'd like to see how you connected your hoses to prevent flow restriction and/or binding/catching during operation. Also, did you have to get any adapters from the original pipes to your hoses or the valves you added (i.e. are the threads different)? I tried posting this earlier but don't seem to have been successful with getting it to post so I'll repost...do you have a parts list of the parts you used for this (including hose lengths)?
I'll try to get the pictures you're looking for. I did use adaptors that changed from Komatsu to "regular" fittings so that I could find hose replacements more easily when in a hurry. Greg
Here's a video of a PC50UU-1 running a breaker. You can clearly see the operator using the foot pedal for the offset boom to run the breaker. http://www.youtube.com/watch?v=MvyJoHKUOe0 Greg
See if these help. I'm not sure what views you're looking for. Greg
Hi!! new member here and new to excavator, I also have a Komatsu pc50uu-1 Blade control lever won't move and blade won't go up or down
Glad I found this thread, I have the same machine and exact same problem, I'm not a mechanic by trade but can generally get stuff to work. I would appreciate it if you could send me some help/pictures/diagrams of how to remove and clean the pump so I can check the suction section on my pump. My symptoms came on slowly and my machine does sit for long periods of time. Many thanks ! Greg
I'll try to get some pictures tonight. Greg
Very much appreciated, hope your machine is still running great !
The machine is running great, Thanks. There are two filters for the hydraulic system. The first picture is the primary filter on the return oil side of the system. It's located up top of the hydraulic oil tank under the large cover with 4 bolts, right next to the fuel filler neck. On my machine that filter is P/N 07063-01054. the second and third pictures are from underneath the machine, looking up at the bottom of the fuel/hydraulic tank. If you swing the machine so that the bucket is off to the right side, you can lay between the tracks and look right at it. The large pipe connected to the 4 bolt flange is the suction oil line going to the pump. Underneath the flange there is another filter that I was totally unaware of initially. Mine was P/N 21E-60-11130. Changing that one cured all of my symptoms. Unfortunately, to change that one requires you drain the tank. You can see in the picture there is a drain plug next to the flange. The ball valve is the fuel drain. Good luck, and let me know if you need any other shots. Greg
Thanks so much, I'll do the filter change first, I too was unaware of the second filter - these are very reliable machines I've found, I expect to do the hydraulic thumb next. Greg
What type of hydraulic oil do you use?
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
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
52 liters, or about 12 gallons for a normal change. Greg
Awesome ! Thanks Again - trying to locate where to buy filters now. Greg
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 ?
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.
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
Picture? Did i miss it from an earlier post?
Post number 39 in this thread, I posted pictures of the filter locations for you. Greg
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?
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
Thanks Greg, engine running or off?
I've always done it running. Greg
Thanks !
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.
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
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
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
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
Thanks - it was low - but not empty, strange that it has it's own reservoir - but now I know it's there - I can check it. Thanks again for your help ! The hydraulic guru is supposed to come by this afternoon, but then again, he was supposed to come by last week too
the reservoir is for the gear lube. The hydraulics for the motor feed from the same system that everything else does. Greg
Hmm, hopefully the gear lube required is the same 30W non detergent as the rest of the machine
that's what Komatsu's manual specifies. Greg
And the verdict is; All three functions that are weak, are run from 3 different spools, Right track on main spool Left track on 2 port spool Blade on 2 port spool with fast travel foot control All three spools are fed by separate pump sections So - verdict is a new reseal kit for the rotary manifold and a rebuild of the manifold The Hydro mech says he can do that - If I can get the reseal kit so that's the next challenge ! A new day - a New surprise
Hey guys, I also have the same machine (1997 pc50uu-1 with 5200 hours, bought it at 5000hrs rubber tracks). I was wondering if any of you guys can comment on the strength of your final drives? Both of mine have been replaced by aftermarket units. The left replaced by the previous owner and the right was replaced by myself a couple month ago -shaft snapped on the old. The tracks will spin no-matter-what when both are going in a straight line together. But as soon as it gets hot, i have a tough time getting either side to turn individually without stalling the final drive out. I have rebuilt the center swivel. both final drives are new (not remanufactures). And the relief pressures have been set at 3100psi and 3200psi for pump 3 as per manual (however when i set them the machine was not "hot"). All other functions seem to work fine. all of the track idlers are in good order. i even put in top rollers on both sides to replace the original steel rub plates. It has been a great machine so far, but the stalling final drives have me frustrated, especially when in tight places! Please tell me the weak turning ability of this machine was not innate to this model! i'm starting to think i have something faulty in my main relief valves, or spool valves? Any help is really appreciated!
I your blade HYdro OK, ie: can you lift the front of the machine with it? As an off chance - check the spooler the road gear works off. Mine is currently stuck in high gear - and that is routing pressure differently to the drive motors. I know that when in road gear, the steering was affected - as well as the push power.
Hi Ruffles, Mine is very similar to what you describe. I have also replaced a final drive and set relief pressures. Mine turns very well when the oil is cold, but gradually loses turning power as the oil warms up. I was going to look into resealing the swivel joint, but you may have saved me the effort. Although mine is weak when warmed up and trying to steer with one track, I can always turn well by counter rotating the tracks, even when the oil is hot. That always helps in tight spaces. Mine also pushes very strongly in a straight line, using both tracks. I've pretty much just gotten used to the turning and work around it. Mines got 8400 hours now and still runs like a champ. good luck! Greg
5400 hours on mine, got the seals for the swivel rebuild, the Mech will turn up one day to do it I hope as I have neither the space nor the tools. Got my drive motors serviced last year, always hod one track a little more powered than the other - just the characteristics of the machine. Greg
komatsugreg, The front blade seems to work OK, it will pick the machine off the ground no problem. It does tend to gradually go up or down if i'm not paying attention, but not frequently. I think the blade wandering might have more to do with the lever linkages that i tried to tighten up and "rebush" last summer. But if it means anything sometimes my blade will lift when i swing the cab (its pretty infrequent tho??) when you say "spooler" do you mean the spool valve assembly for the final drives? the RH final drive operates off of a 4 spool assembly, and the LH final operates off a separate 2 spool assembly. both fed by different gear pump sections...but i think both spool valve assemblies use the same drain? My high speed seems to work great when both finals are engaged, it will usually bogg the engine down before quitting. but definitely will not turn a final drive individually. Thanks for your response!
Greg, Thanks for the info. sounds like we have the same machine, haha!! Mine also will counter rotate better than just one final operating individually (usually anyways). glad to see your machine at 8400 hours, that means hopefully ive got at least than many hours left in mine! I got the center swivel joint seals aftermarket. it wasn't the easiest job to do, but i did it last winter while the machine was in its downtime in hopes that it would get the RH final drive fixed up, but it didn't do much. The original seals from the dealer were $60/pc and you need 8 of them i think...so i went aftermarket at $40 for the whole kit. In hind site i probably should've known the center swill joint wasn't bad b/c the blow by in any of the swivel "banks" would have caused another hydraulic circuit to move if it were bypassing the final drive "bank"...but it was cheap enough and i had enough freetime to redo for the peace of mind. i'm determined to figure this out, when i do i'll let you guys know too! Thanks again
I got a komatsu style hydraulic tee-fitting a while back that i planned to attach my pressure meter to. Tomorrow i plan on working the machine some more, get it good and hot, then splice into the hydraulic line where it is attached to the RH final drive motor. This will at least tell me if the full 3100psi is getting to the final drive motor or if its bypassing somewhere. I've also heard (it may have been somewhere on here) that if the final drives don't see enough FLOW then they will essentially try to apply the brake and become difficult to spin...however i'm skeptical, b/c throttling the engine down would essentially produce a decrease in flow more so than any wear and tear would reduce it at full throttle... The valve body/main relief valves are the only thing i can think of unless gear pump FLOW is something terrible. I dont have access to a flow meter, and last i checked my cycle times are slower but aren't terrible compared to the specs indicating flow is OK. Hoping someone on here has solved this riddle already. Its a great machine otherwise, i just cant get the tracks to spin like i think they should!!
So the full 3000psi is making it to the RH final drive when hot, and the final drive stalls out. have a call into the final drive supplier, hopefully he can provide some insight. The LH final drive is still going strong. Will let you guys know what i find out.
They'll probably need you to do a case drain test. The procedure is pretty straightforward and spelled out in the manual. Greg
Yes they did have me do a case drain test, very little (hardly anything) was getting by. No real answers yet. They are having me send the final drive back under warranty and will likely send a replacement out once they get back in stock and inspect it. I am letting the supplier lead the way on this, but doing some more reading on where these final drives come from -manufacturers in particular. Originally the pc50uu-1 came with Hy-dash final drives (obvious from they big letter on faceplate i know). That was a gmo5, which i've read was discontinued in 2004? But the aftermarket for final drives seems to be pretty vague about manufacturers and countries of origin. The aftermarket on my left side (the good side) i've been told is a "Nabtesco" unit -model# gm06vn-b-15/26-2 that says "made in Japan"...its pretty strong. Nabtesco is somehow related to hy-dash and Teijin Seiki? "Nachi" is another aftermarket supplier out of Japan that also has a good reputation, but is a competitor to nabtesco...so idk how well that brand would match my good unit. The unit i bought was pretty close on speed, but strength was no comparison. The supplier has been pretty easy to work with so far, just hoping a replacement resolves the low power...will let you guys know how it goes.
I have a similiar issue with my Komatsu PC50UU-2. I still have both Hy-Dash Drives and I have 5500 hours on my machine. Has anyone found an answer to this issue?
OK, my machine is back and running. Problem was the spooler that the road gear pedal connected to. It would not let it back into regular mode. Mech took it apart - cleaned and resealed it and all is well. Turns out I have a set of seals for the swivel joint that I no longer need ! I want to thank all who chimed in with responses to help, much appreciated
WestsideRida, I haven't solved the mystery yet. I just learned to live with it for now. I have pressure tested the hydraulic supply and have 3000psi to the final drives. The only thing mine can be is a flow issue with the pump (its still original with almost 5300 hours) or its a faulty final drive. I've got some projects to finish up before the snow starts falling, but when i put it away for the winter i will go through some more stuff and let you know what the problem is. Another forum i came across a guy that had the same issue, he said a new pump fixed him up. which he said he got from whitehouseproductsltd.com out of england. I ordered one from there at 1/4 the price of my dealer, but it didn't hold the pressure and this was before i replaced the last hydash final drive...the pump ripped the threads out of the mounting flange and all 3 sections separated losing pressure. it was only a a couple weeks old....another project this winter is to get some sort of refund and will likely try to get Parker pump model PGP511 which looks to match all the specs and still about a 1/3 the price of my dealer. I believe Parker is american made, and the specs say it can withstand 3600psi working pressure so it should hold up better. I also went as far as to switch the final drives from one side to the other. it seems the weakness traveled to the other side, but they both seem a little weaker now. So it might be a weak aftermarket final drive unit along with a tired pump. The place i ordered the final drive from agreed to take the final drive back to see if there was anything faulty inside. Just waiting for winter when its in storage to send it back I am slowly restoring this machine, so i will get to the bottom of it and i will let you guys know. Best of luck, hopefully someone solves this before me haha
Hello new to the site,,, was wondering if anyone has a computer for a pc50uu-2 Or a place that might fix mine,,,, supposedly boom tensiometer ground curcuit is shorted to ground in computer. thank you my number is 8704051813
Well the beast is fixed - as far as the hydraulic problem went, but now the glow plugs are not heating up First one quit, then the second, then the last one and now it won't start. Soea anyone have a source of new plugs - and a procedure for making sure it is actually the plugs and not a relay bank or something else that died? Seems like my diagnosis of problems is always in the wrong direction.
You can test the glow plugs with an ohm meter. A good plug will show some resistance through it. A bad plug will be shorted through, ohm meter will show zero resistance, or open circuit, ohm meter will not move. You can test them in place and use the engine block for ground for the test.
Thanks very much I'll give that a go, If they have to be replaced, do you know of a supplier? I'm thinking FridayParts may have them but am always open to different channels.
Found the problem(s) The glow plugs are connected by a tin bar that runs across their heads and are held in place by nuts. There were no lock washers on the nuts and they vibrated lose - just enough to cause a resistance from corrosion and prevent the plugs from getting full current,
Glad to hear it. Another quick test to see a short plug is that the bar will be discolored just ahead of the shorted plug. I usually throw the lock washers away. They don't do anything but give you the type of problems you just found. Nice Work!
Sorry to hijack this thread. But it appears to be the only active PC50uu-1 group out there. I've very recently picked one up, about 3500hrs, steel track with full cab (blown out front windscreen and homemade bent up door). Everything seems strong so far. The left joystick controls are non-ISO and would like to switch the existing stick-swing control set-up around to ISO. Left hand left = Swing left. Left hand right = Swing right. left hand forward = Stick Boom (Dipper) away. Left hand back = Stick Boom (Dipper) close. Currently it is. Left Hand left = Stick away Left hand right = Stick in Left hand forward = Swing right Left hand back = Swing left. Have any of you switched to ISO controls and if so how? It doesn't appear to be as easy as I had though it would be once pulling the covers and looking at the array of push rod/bell cranks and two separate spool valve packs. Maybe just get use to existing controls. I'm looking for PDF service/shop manuals, but the sites offering them look dodgy, anyone had success with any of them for their service manuals? Sounds like the hydraulic oil is 30w non-detergent as well as the swing motor gear case but how about the final drives? Heavy gear oil or the same 30w as everything else? I'd really like to do a fluids change before (especially final drives) before working machine. Big thanks to everyone who has posted there. Greg your pic's for the thumb install and plumbing plus the part numbers for the hydraulic filters is perfect, Thanks again.
I've never seen a Komatsu spec show 30w non-detergent oil for the hydraulic system. What I have used in all the Komatsu excavators I have worked on was an AWS 46 hydraulic oil. All the gear train stuff in the past was 30 wt. engine oil. In my experience it isn't very easy to find non-detergent oils now days. Your description of the controls sounds like you have a manual controlled machine and not a pilot operated one. Some photos of the cab and linkages would be helpful. If it has manual controls it is a lot of work with cutting linkages and repositioning bell cranks to make the change. If it is a pilot operated machine it just involves swapping some pilot hoses.
The Komatsu manual for the PC50UU-1 does in fact specify 30W non detergent for virtually the entire system, including the final drives. From memory, it seems like there were mechanical provisions for changing patterns. It is not a pilot system. I will go through the manual and see if I can find what I think I'm remembering. I did download a manual from one of those sites, it worked well. I can try to email you the PDF if you like.
I'm thinking it must be an old gray market machine then. Any idea of what year it is?
Thanks for the reply's. Yes it is an old gray market. Not sure the year but it's serial 5840, guessing late 80's early 90's. I received this morning, a PDF Shop Manual emailed on to me by another member on the forum here tool_king. Huge shout out to him for that, trying to figure out how to buy him a beer from across the border. I'll pour over it and see what I can find for swapping controls over. I did find on another equipment forum a member mention he swapped his controls over on his old pc50uu-1 by swapping the lines coming off the spool valves ... and he didn't have any issues with hydraulic flow. That said, I could see that potentially being a problem and have been advised that I really want to swap at the linkages (mechanical) not the spool valves and there should be a way. I'll post back with what I find and how it works out. Sure appreciate your thoughts.
Alright, figured it out. This version of the pc50uu-1 has a square bolt with one side shaped to an (indicator) arrow, at the base of the left hand pedestal. Inside of pedestal it was a simple lever pointed into the bell crank cluster. Of course with it at floor level any markings were obliterated and looking down on it from inspection plate removed on side of pedestal I assumed it was some kind of manual control lock out that had been disconnected (turns out the actual control lock out has been completely cut away), as it wasn't nested into a slide plate which sits on top of bell crank cluster. The clue I missed was that there were two push rods coming off the fore/aft of the left joystick; one actuated a bell crank connected to spool valve (at this time the swing) and the other was hooked up to a non-functional bell crank on the oppose side of the shaft the bell cranks pivot on. I assumed the non-functioning one was some kind of mass balance or stabilizer. Well after tearing pedestal apart and getting my hand under the "slide plate" realized there were tabs on the top of two of the bell cranks that the slide would flip 90degree to engage or disengage adjacent bell cranks; thereby changing controls from old school Japanese to ISO controls. Kind of ingenious but as the control selector wasn't hooked up to the bell crank slide I would of had to tear it apart anyways. And be forewarned, I had a heck of time getting the pedestal back over the push rod cluster, in the end I had to leave the fore/aft push rods attached to the main joystick knuckle, the side to side push rod disconnected at the push rod turn buckle. Dropped the pedestal onto the joystick, attached the fore/aft knuckle to pedestal then dropped the side to side upper pushrod with knuckle down into the main knuckle from above and pined it in place while reattaching at the turnbuckle. I'm assuming it was do to the lack of space and difficultly in reinstalling pedestal that a previous owner cut the control lock out off. Pics show the slide plate on top of the bell crank cluster, tabs to "flip' between different bell cranks located under it. And the mystery indicator/selector at base of pedestal.
Congratulations for sticking with it and figuring it out. It is supposed to be a simple mechanical changeover, then. It sounds like you were able to accomplish your goal even if it was more than you initially intended to get into. Now you'll be able to point the next guy in the right direction! Greg
Wildfire Glad it worked out for you .It is always great when you can get you machine back up and running.
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
I don't recall that a lot of those came into the country back then. All the mini Komatsu excavators were a little bit different than the larger ones. Most that I have had the occasion to work on had Yanmar engines in them. The pumps were gear or maybe one gear pump and a piston pump. The valves all worked differently. Maybe a photo or two might help jog a memory or two.
I know those are not very good pictures, but maybe you'll get the idea. I don't even have the yellow (running) one home yet.
Those are articulating boom units. I don't see the potentiometers for the stick or boom so you might be OK to run them here. I see a lot of hoses capped off on the green machine. I've never had the "pleasure" of working on one of those. You should be able to get any parts you need from the Komatsu dealer. Just give them a serial number.
The green machine has the swing motor and gearbox removed, so there are lines unhooked just laying there. The idea was to get a machine with a parts machine and hopefully be able to keep one good machine with an extra of eveerything, but if I can get both running for a reasonable price, then I may do that.
What general area of Washington are you in?
Just north of Portland on I5.
I only get through that area once in awhile. You might have to settle on making one machine out of two. You are right about the parts and maybe you can find a machine knocked in the head for more parts to get the second one running. New parts will be very expensive.
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
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 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.
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.
I'll look and see,I use napa proselect filters..so much cheaper than the oem.
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.
I'm very sorry, I sold the machine a couple of years ago. Greg