Need some help please. I bought a 2010 Komatsu SK820-5 skid steer with pilot control joysticks. It was working fine when I bought it but had a pretty severe oil leak that appeared to be coming from the wheel motor lines. So I ordered and replaced all the wheel motor lines. Marked each line with which port it went to and I also have full factory service manuals. Well 1 line was back ordered for 3 months and I left all the lines unhooked and the hydraulic system basically fully drained. So today I installed all the new lines, primed the pump and followed the recommended bleed & tank pressurization/depressurization proceedures… about 5 times now. So everything works EXCEPT TURNING! I can't pivot or turn going forward or backward?? it travels forward and backward perfectly even in high speed but it WILL NOT TURN??? I'm freaking stumped? I've checked and rechecked the lines and they appear to be correct. I never touched the pilot control lines and the machine was turning fine before this?? When I try to pivot, I can hear the pump pressurizing but the machine just creeps backwards but doesn't pivot left or right. If I go forward or back and try turning, I can hear pressure building but no turn?? Any Ideas? John
Sounds like air trapped somewhere? Losen a line or something on that circuit to get air out?
Thank you. I presume you mean in a pilot line? I can't imagine it would be a wheel motor line since they drive well in both directions so I'm presuming one of the joystick pilot lines is air bound? Ill try that tomorrow. So you think air could have gotten into a pilot line even if they were never loosened?
Maybe blocking it up off the ground so there's less load would help to bleed air out.
I'll try blocking it up also. As my first Pilot control machine... I just don't understand how the pilots work? I feels like the pivot/turn pilots aren't actuating that portion of the pump but i don't know if the pilots can get air bound like a hydraulic clutch master/slave cylinder OR it they have feeds and returns and self bleed? Also- the service manual says the pump must be primed by filling a plug at the very top of the pump. The first time I did this, the pump took about a gallon of oil. After running the machine and seeing that the pivot/turn wasn't working, I rechecked the pump fill and there was again air in the top of the pump ..so I tried refilling it but it seems the pump oil just drains back into the reservoir and it seemed like was over filling the system. I'm going to drain some today and try topping off the pump again. I wish I had a better understanding of how the system works.
Is that Komatsu hydraulic over hydraulic controls? If so, lower pressure and flow hydraulic circuit runs to the joysticks which actuate the larger main valves for each function. It's also possible that some dirt or debris got stuck in the 'balancing valve'. Not sure what they call it exactly, but it's the valve that adjusts flow between left and right drive.
Ok so more info but I'm still struggling. What I did this morning. 1) I blocked the machine up in the air so the tries can spin free. 2) I refilled the hydraulic pump to the very top from the priming port. 3) I ran the machine up on blocks. NO change... forward works great- reverse works great. if I do a turn in forward, it does slow down the inner wheels of both left and right turns but this is up in the air- on the ground the "force" on the slowing wheels doesn't seem to actuall slow them so no turns. 4) in reverse, it also slows down the inner wheels but again, this is in the air - no effect on the ground. 5) if I pivot in the air, one set of wheels spins in reverse but the other set stays stationary but I noticed something interesting. The wheels that spin in reverse are the WRONG wheels given the pivot direction. For example- if I command a spin to the left, I would expect the right side wheels to spin forward and the left side wheels to spin in reverse so it would pivot to the left … BUT when I push the joystick left, the right side wheels spin in reverse and the left side stays stationary!. Same thing if I command right side pivot I'd expect the right side wheels to spin in reverse but it's actually the left side that spins in reverse and the right side stays stationary????? 6) I loosened all 4 pilot lines from the left joystick where they enter the pump. I then started the machine and moved the joystick in all 4 directions. All 4 lines sprayed oil (made a mess!!). Retightened - cleaned up and retried the pivot... SAME THING!!!! UGHHHHH! I'm so frustrated!!! 7) I printed out the hydraulic schematic and traced every line... unfortunately- the schematic labels wheel motor and pump ports alpha numerically BUT- there's no "key" or legend that defines where the ports are on the actual pump or motors and they aren't marked?? Useless info if th ports can't be identified! 8) I printed out the parts book for all the lines that I touched and the parts book labels each line and port... my lines and ports match up with where the lines are supposed to run at least as far as I can tell from the parts book diagrams. 9) to add insult to injury... this whole exercise started because while the machine worked fine, there was a significant hydraulic leak inside the belly of the machine. So... close to one grand in new lines later and a whole lot of AND- the machine no longer turns AND....would you believe- it still freaking leaks!!! I'm really not having a good weekend!!!!. Any help would be appreciated.
How many hoses did you replace? Did you triple check you put them all back in the same place?
I triple checked and verified all the lines (about 10 of them) against the diagram. Also -if I had hooked them up wrong I would think forward and reverse wouldn’t work as well as it does???? Also- I changed none of the pilot lines. I switched every hydraulic tank return line (6) plus the 4 wheel motor drive lines. And yes- the machine is hydraulic over hydraulic pilots... not EH
well... calling in a pro. Can't get past this. Does anyone here understand the main drive pump? I've been doing a lot of reading and it looks like mine has dual, variable displacement piston pumps with the main ports in each pump variable between suction and discharge via the swash plate. All that makes sense IF one drive motor was plumbed to 1 pump. BUT in my case, it seems 1 port from each motor is going to 1 port of each pump... wouldn't his mean that you could literally send discharge pressure to both ports of 1 drive motor??
You'd better recheck your plumbing. My case and takeuchi, twin pump, machines, are one pump per drive motor. A & B are the propulsion lines, right above each other, in the Sauer pump show below (only one pump of the pair is shown).
I've checked, re-checked, re-re-checked & re-re-re-checked the plumbing about 10X now! I've checked it against my notes. I've checked it against the parts diagram (shown below color coded by me following the a b c d lines) and I've checked against the hydraulic schematic. They all match and they all show the hoses crossing over as shown. The ports on each side of the pump represent 1 port for each pump... there's one "forward" pump closest to the engine, and one "aft" pump away from the engine.
Here's an internal view of the dual pump with the color coded lines. See how each drive motor goes to each pump??? This doesn't make sense to me??? It seems like you could send pressure to both sides of one drive motor??
I would double check that AC and DB are in the right spot on the pumps. The manual may show them reversed visually.
To me that picture is wrong. A & D (yellow/black) should go to one motor. B & C (red/green) should go to the other motor. Basically front pump drives one motor, rear drives the other. They shouldn't cross over.
Phil- I hear you! I thought so too! BUT- I methodically marked the lines when I took them off. I put the lines back on using my notes and when it didn't work...I immediately thought "I screwed up putting them back on". After I rechecked them AND confirmed it matched my notes- I checked them against the parts diagram (picture I posted above). The picture I posted above MATCHES my notes exactly! SO BOTH my notes AND the Komatsu diagram would need to be wrong... in the exact same way???. How likely is that?? Also- I crossed checked all of this against the Hydraulic schematic and while the schematic uses port numbers that I can't match up to anything... it shows the motor line swap?? I wish I understood these systems better but MAN- I can't seem to make sense of this. I'm almost tempted to swap lines d & b but with everything matching up... I don't want to "create" new problems.
Skata- I've checked these so many times and everyday I recheck them thinking... hoping.. I'm missing something. I've considered (and fully expect) that I did something stupid and just haven't figure it out yet. The one saving grace is that of these 4 lines, 3 are the same exact part number BUT 1 is different. 3 of the lines, where they attach to the wheel motors, have a 90 degree elbow BUT 1 line - line b (green) has no elbow. It's a straight fitting on both ends and it can only go on the right side motors bottom port... it won't fit anywhere else. That line has become my sanity check. I even thought at one point that I screwed up my "left and right" notes on the lines thinking that I was referring to left and right as I'm working on the machine from the front (which would reverse left and right). BUT that line was marked " Right drive motor- bottom port" on one end and "Left side pump- rear port" on the other. All the other lines are likewise marked and there are no duplicate ports. If I find out that I screwed up my markings AND the diagram is also likewise wrong... I'm going to flip!
jav ; It may be possible the lines were not connected correctly before you disconnected them. phil314 may very well be right. Change them like phil's drawing shows, you have nothing to lose but some time.
Unlikely, but if everything was correct - the machine would work. lol. Here's what I'd do. Swap B & D at the pump. I'm betting the machine will turn just fine then. However, turn right might go left and turn left might go right. If that happens then Swap B & D back and swap A & C. Here's my understanding. You've got a front pump and a rear pump. Flow out one side is forward, Flow out of the other is reverse. So if you swap sides on the same pump the motor will turn the wrong/reverse way. If you swap both hoses front to back, you are swapping which pump controls which motor. In all cases each pump controls only 1 motor. You never have one pump attached to both motors. So no crossed hoses. The fluid has to flow in a circle. If you did, you would only move when operating both pumps at the same time. In that case you could go forward and back but not turn. Hope this helps a bit.
It took three times to get the final drive to shift right on my PC300-5, as both the parts manual and service manual were wrong. And my Takeuchi parts manual has hoses going to the wrong ports on my TB180FR. Just saying.
I'd transpose the green and black and then retry (wheels off ground, of course).
Guys... I'm headed out to try it. It's been my gut feeling to try this but not knowing too much about these, I was afraid to do more damage. If this works i'll be happy and pissed - if that makes sense.
Bad news... seems like I jumped from the frying pan into the fire. So I swapped hoses b & d at the pump. Started the machine and now not even forward /reverse is working. Plus the system sounds very strained and like a pail full of marbles. Clearly this was worse. I immediately swapped the hoses back and now forward and reverse aren't working with the hoses back to to where they were before?. It seems like it could be air but I swapped the new hoses in dry and it never sounded like this and I only lost a little bit oil during the swap. The wheels do spin forward and reverse in low gear- not in high gear ( think I have the high gear solenoid unhooked so I'm not concerned about that) but- even in low- they don't sound smooth like they did before... not sure if its because the wheels are up in the air? UUUUHHHGGGGG. feeling dejected and definitely don't want to do damage to the system. thoughts?
There is sufficient oil in the system, right?
the hydraulic tank is above the full mark. I also tried priming the pump and added about 1 gallon directly into the drive pump so I believe there is sufficient oil.
Could you be driving over the brakes? I dunno what kind of braking system is on there, but, does it have a separate hose and valve for braking? How did you seal the system when hoses were off (did you leave a rag or plug in the system)?
brakes are electronic. Tied directly to lap bar and an e brake switch, Hydraulics can't be activated unless lap bar is down AND e brake switch off. I did not seal the system for the one swap. The fittings were right next to each other and are o-ring face seal fittings so both were loosened, one removed, the other removed and plugged right on to other port and then the first hose swapped to the empty port. Hose fitting face up so hoses stayed full of oil while the pump fittings dripped perhaps 8 ounces of oil during the swap. No plugs or rags used. also during the wheel rotation, it seems like the wheels spin free then encounter resistance. Adding throttle can actually increase resistance. I hope I didn't booger the pump?
What other lines did you replace? You replace any suction lines? Could air be getting in the system?
Thanks for the suggestions guys... got a good nights sleep and have a little clearer mind. Heymccall- you may have been on to something with the brake. In my post 7- item 9, i mentioned that after replacing all the lines, the machine was still leaking. After putting the machine up on blocks to try to work out any air and to try to relieve back pressure for pivots/turn- I was making no headway on that front and decided to look for the leak and I did find one solenoid that was leaking. I pulled that solenoid (which was in a group 4 solenoids and was attached to the manifold with 2 screws) to check the seal. I found that the bottom screw holding that solenoid was broken off in the manifold so the o-ring face seal was leaking at the bottom. I have to pull the whole manifold to drill out the broke screw and re-tap the hole. Not wanting to add another variable to my current woes- I replaced the face seal o-ring with one that was slightly thicker and put the solenoid back (with just the 1 screw) just to seal the hole and left it unhooked (electrically). I thought that solenoid was the high speed solenoid but just looked and it appears it's the brake solenoid... so you appear to be clairvoyant! Now- I re-plugged on the electrical connector and retried forward reverse but it's no different than with it unhooked BUT- I did loose some oil in that circuit when I pulled the solenoid and while it looks to have seated correctly in the manifold, I'm not sure if the thicker Oring is keeping it from "fully " seating. I think it might be possible that an air pocket in the line or manifold is preventing the brake from fully releasing and may actually be causing the high speed solenoid (also in the same group) to not actuate? Certainly if the brake is dragging, High speed may not work at all? it makes sense the brake may not be releasing. Any suggestions on bleeding those circuits? Skata- No. I didn't replace any suction lines. Plus the only thing I changed from when the machine worked forward/reverse but no turn- was the solenoid mentioned above and swapping the b c lines. Nothing else was changed.
One pump per motor. 2 pumps 2 motors. The same lines (high pressure) per pump should go to the same motor, they shouldn't cross over. If you have forward and reverse, as it seems you have...….the steering part of the system is the reversing of the pump swashplate to gain oil movement in the pump and motor flowing the opposite direction. That is controlled by either pilot lines, or electrical signals depending on the type of system you have. I haven't seen very many systems that require "bleeding" of the lines themselves. Once there is movement of the oil from the pump, they will self bleed in most cases I have seen. I am wondering if you are too concentrated on the bleeding and overlooking what the actual issue is. JMO of course!
vetech63- thanks for the input. I'm mostly focused on doing no harm. I'm not super knowledgeable on how these systems work so I'm doing a lot of reading and trying to "understand"... hence my color coded diagrams and frequent reference to the manuals and theory of operation, and asking for help here. I'm also waiting on an experienced tech to come by but every night, I try again- hoping to learn and maybe even have that AHA moment. Unfortunately, the manuals describe the functions of each component and in the case of the dual pump- it explains how 1 pump/swashplate works BUT doesn't explain the interaction of both pumps together to generate turns/ pivots. Also- after reading theory of operation, I come away with the same general understanding as many here- being 1 pump- 1 motor- no cross-over BUT- clearly the diagrams and my notes suggest otherwise. And, in the back of my mind, I don't "think" the cross over is impossible because I would think the drive motor circuits can't be a "close loop"... in other words, there can't just be a supply/return directly from the pump to motors or the oil would eventually overheat... there has to be a bypass to send at least some of that oil to the cooler as well as a pickup to draw fresh cooled/ filtered oil back into the circuit... no? So from that standpoint- not understanding those cross flows leaves me guessing and certainly reluctant to presume the manual... and my notes are BOTH wrong, which is where I am now. Also- not being super confident, I'm trying very hard not to change too much all at once... keeping the variables to a minimum. That solenoid thing is a good example of something I touched without "really" understand the possible impacts it could have. I thought I was just addressing a "leak" when now after at first dismissing Heymccall on the brake thing... his outsider thought process logically made me realize I likely caused the brake problem which means my b c swap test may have been invalid IF the brake circuit was not released! I know its it more likely than not that I caused these problems but for the life of me, I haven't figured out what I did, or failed to do (yet).
Most systems are closed loop but have a charge pump and case drain. The charge pump also replenishes oil lost through the case drain(s). Not sure what your machine has but sounds like you need to get someone more familiar with your machine to come and look at it in person.
Dave- wheels are VERY sluggish and resistant to turning. Thanks for the info on the charge pump and drain... that fills in some gaps. I Did some quick testing at lunch. Brake fuse is good. The brake solenoid is getting warm so I suspect it is getting power although I didn't have time to setup a probing method for the (female shrouded) connector to verify voltage. I cracked the pressure hydraulic hose coming from the brake solenoid output to the motors brake ports and there was no flow or pressure with the e brake switch depressed or released...so it would seem to me the brakes are not getting released hydraulically if they require pressure to release? The next question is... is there no flow at the hydraulic line because the solenoid is not functioning OR because there's no supply pressure to the manifold itself? I just looked up how the brakes release at the wheel motors and how the manifold gets supply pressure and it seems the motor brakes work via hydraulic pressure "RELEASEING" the brakes... they are normally engaged when there is no pressure- so the fact that no fluid is coming out of the line while cracked suggest the brakes are NOT disengaging. On the solenoid group- here again the manual sections are conflicting and incomplete. On the theory of operation section for the valve group, it says the manifold galley gets pressure from pump port "E1" .. and ... When I trace that line on the schematic, it goes to a main pump port shown as "E2" (there is no "E1" on the schematic). Now- on the pump diagram- or on the pump itself, none of the ports are labelled at all so I can't identify either E1 or E2 . looking at the parts manual, the line does not run to the charge pump section but to a port at the top of the dual pump near the priming port. One odd thing about this upper part of pump is that the manual tells you to fill the pump cavity to the top to "prime" the pump. BUT- it seems like there is a return line somewhere that prevent the pump from completely filling up? I fill it till it overflows and it drains right back down to about 2-3" below the top. This port which send pressure to that manifold is right at the top so I could that air pocket be my problem?
Well gents...the saga continues. Thanks for all the great insight and I'm actually feeling much more comfortable that I somewhat understand the system and I'm pretty sure my no turn problem is related to the motors crossing over between pumps... which means the manual and my note are wrong BUT before I can prove that, I have confirmed that the brakes are NOT disengaging by; confirming that the brake solenoid is getting power.. but no oil pressure or flow is getting to the brake release ports on the motors. I pulled the solenoid, cleaned it, bench tested it and it worked.. meaning the spool moved when the coil was powered up. I re-installed it, tried it again and still no flow . Thea solenoid continued to get hot & leak through the case so I figured- bad solenoid. I called Komatsu to get a new one... and they said the part number in my parts book is invalid, it may not be available and they said they would research it but they never called back. SO I pulled the MFG part number off my "bad" one and after much research, I found a very similar one locally at a supply house. By very similar I mean -same manufacturer, same base part number, same body, same dimensions, same function (3 way - 2 position) same voltage, same connector... but the komatsu version has a diode in the coil and this one does not and there is something "proprietary" about my exact part number that belongs to Komatsu and they would't tell me what it was BUT... as far as the MFG was concerned, the alternate I found "should" function exactly the same but for a possible voltage spike back fed to the wiring when the coil de-energizes. I bought it and installed it... no change... still gets hot - still not output pressure. SO- I got out my pressure tester, fashioned the appropriate adapters and tested pressure out of the pump into this 3 valve manifold. 375 PSI which was in spec. Reconnected the line and tested pressure out of the solenoid output port. 0 PSI energized or de-energized... no output. so I pull the solenoid and as soon as the screw thread releases, the solenoid shot out under pressure (there is an accumulater on the manifold block). SO -I pull the output line at the brake motor and using compressed air, blew it back towards the manifold (with the solenoid removed) and the line is clear. I started the engine and oil shoots out the solenoid hole.... thats clear. I put the new solenoid back in, tighten it up and retry the output test and again- no output pressure. I re-verify voltage... it's 14V. SO it would appear the solenoid is NOT opening??? BTW- i confirmed the solenoid is rated to work unto 650 PSI. on ports 2 & 3 (work, pump) and 50 psi on port 1 (return). I suppose there could be something structurally wrong inside the manifolds solenoid bore but *** am I missing? Tomorrow i may check if perhaps the tank return is getting pressurized above 50 psi? there is no manual override on the solenoid or would have tried that. thoughts?
Solenoid is on but no flow you say? How about when you attempt to move the machine?
well i don't think the solenoid spool is moving to the on position but there is 14V at the solenoid connecter AND there is 375psi at the manifolds pressure port but there is no flow or pressure at the solenoid output port. For some reason the solenoid is NOT directing the pressurized oil out to the output port when its energized. Last nite I had the thought that perhaps the connecter has voltage but maybe when I plug it onto the solenoid, the connectors female contacts aren't effectively transferring the voltage onto the solenoid male pins? While I think that would be possible- I do feel the relay body heating up when it's energized so It is my belief that this heat is from the electrical energy and not from hot oil since because I usually try this right after startup so the oil probably wouldn't get that hot that quick?? But I'm trying to think of anything and everything to explain whats going on? Todays plan- confirm with the Hydraflow (the manufacturer) that the solenoid does for sure have the 12vdc coil (which they said it did yesterday but like everything else- i take nothing for granted) and... I'm going to machine up a spool to put in place of the solenoid that will temporarily connect the manifolds pressure port to the brake output port so I can confirm that when the brakes get hydraulic pressure, they release and that the motors spin in forward/reverse freely...getting back to where i was about 5 days ago.
Check the coil on your solenoid. It may be getting power but not working. The easiest way to tell is to remove the nut holding the coil on the valve stem, then make sure it has power to it. It should feel magnetized to the stem if working properly when it is under power and grounded properly..
Vetech- this is the solenoid... it's not the typical stem cartridge with removable coil. I did confirm the coil resistance at 7.6 ohms (same as my other one) and I can feel that the Housing is getting warm. Also- power and ground are applied at the connector so the body doesn't need to be grounded for it to work.
I'm just waiting for you to find something stupid as to the cause, like maybe an unplugged connector or something...
LOL- me too! I highly doubt it though... I have voltage and pressure at the stop solenoid and I can cycle the voltage on and off with the switch so electrically, I think it's working.
Well good news finally! The machine is fixed and I did it myself because the Pro just couldn't make time for me. First- Yup- I screwed up marking the hoses AND the Komatsu manual is wrong in the same way that I marked the hoses wrong. I now know what I did but it wasn't apparent AND it wasn't the only problem... just 1 of 3. The second problem was an aluminum block that houses the stop, 2 speed and servo enable solenoids , rotted away on the bottom. What I thought were broken screws and solenoid leaks were not. The entire lower aluminum block literally disintegrated away and was very likely the source of all my leaks. I had to machine the block and weld in a new section to fix the leaks and drill and tap new fastening holes to properly secure the solenoids . Lastly- the brake solenoid connector, which is a europulg style, had a broken wire inside the rubber waterproof shield. depending on how you held the connector, it would or would not make contact... which explains why the coil was heating up , showed voltage when probed but didn't always work when plugged onto the solnoid. Because the brakes were intermittently not releasing, it caused me to believe my hose b/d swap test made things worse when in actuality, it should have shown that it fixed my pivot issue but -was pivoting in the wrong direction... the problem was actually a hose a/c swap- which is on the right side of the machine. The reason i marked those wrong is because I had removed hoses b & d one at a time and marked each one as i took it off. On the right side of the machine -that wasn't possible because there were 4 other hoses in the way that had to be removed before i could get hoses a/c off. In roving those hoses I had a mess going with oil everywhere and I'm pretty sure i removed both a & c hoses, put them down and then reconnected the other 4 hoses to minimize oil loss. I changed gloves to put on the labels so they wouldn't get oily and fall off. I must have screwed up sticking the labels on after both hoses were removed and on the floor The fact that the Komatsu manuals showed the exact same error as my marking error made me trust my mistake even more. In the end- at least on my machine- each pump needs to feed 1 motor and there should NOT be a cross over as shown in the manual . I'm glad this is over and I learned a lot! Thanks to all who chimed in and helped and put up with my frustrations... I really appreciate the education.
Hey that's good to hear . But how did an aluminum block disintegrate? Solid aluminum?
Solid aluminum... and the machine is a 2010. My best guess, the machine was used near the ocean and for snow removal. My guess is salt got into the dirt and debris that was caked in the belly of the machine. The bottom of that block was sitting in that brine and just corroded. Heres a couple of pics
It looks like it has been sitting in wet fertilizer for years. Normal debris and wetness doesn't do that to aluminum that I have seen...…..but there is always a 1st!
I'm just glad to have fixed it... this thing was kicking my butt!! Also- that block is no longer available from Komatsu. Luckily I have a machine shop in my garage and can weld aluminum. I checked this morning and so far- no leaks and everything works up on blocks. I'll lower the machine tonite, re-install the floor and see how she runs on the ground.
Did Komatsu change the material or something that it's no longer available? I wonder if being wet like that somehow contributed to extreme galvanic corrosion between different metals. If they use lots of salt in the winter would certainly accelerate it. I know on aluminum body F150, you have to insulate the body from contact with steel even for simple things like installing mud flaps.
the block is mounted to steel studs … it's a possibility. I don't think Komatsu changed the material but the did stop making skid steers so I presume it's juts a part they no longer support?
Put the machine on the ground last night. Works like a champ... even better than before since it seems the hydraulic system makes less noise? Perhaps the leaks were allowing air in? Sounds really good now. Also- got up this morning, and everything is dry. All is right in the world.