Just bought the machine it came in dead, when I say dead I mean it.... The sticks don't get heavy or anything. The guy I bought it from said the pumps were bad but I've not seen one that just went completely out, normally they just get weaker and weaker. The thoughts I am having right now is, flywheel to pump coupling, or electronic and such as operate lever switch etc. How do I check to see if the machine is to operate ? On one of my old 200-6 units we had a bad compensator/valve and swapped it with aux and it was good to go..... Does anyone have a diagram of the lolipop tree or the actuator bank etc or any troubleshooting guides. I will add that the delivering company broke a few lines lose so they could pick up the boom to get it on trailer, and when I start the machine there is a very small amount of oil that will come out of the lines, it is not much but it is a discernible difference from the machine not running at all The machine is a 2002 pc228uslc-3. Thanks in advance, PJ
If you have fluid leaking while the machine is running it sounds as there is standby pressure. The pilot circuit either comes off a reducing valve or small pump. If you don't have any T fittings or gauges you can pull one of the pilot lines off of the main valve bank and operate the joystick
Sit in seat. Right hand console. At the back of it there's a cover. Pull it off. There's 3 switches pump emergency drive swing release and can't remember the other the top 2 are locking switches the bottom is a momentary, lift and hold switch up that will tell you ifit's eletrrical or hyd issue.
I agree that I think the pump is trying but just not stroking at all. What would the switches indicate? Does it just full stroke the pump ? We still wouldn't know if we had a bad pump or electrical problems ? Does anyone have a blowup of the pump/engine coupler? Is it possible that it stripped splines or broke pump shaft and is just barely turning the pump? Pj
What is the Dash series?
3 Pj
Figured I would post a pic, I know that I am more appt to click on a thread that has pics lol The first one is a dash1 it's a 99 I think and the other one is a 2002 dash 3 Pj
Update, I had a little time today to mess with it and it seems that the pump lines all the way up to the valve stack are getting super hot very quick it's as if the valve stack are not letting fluid out of it. The joysticks have a little resistance to them and at mid throttle if you center joysticks the motor lugs a little and as soon as you operate a function it rev's up a bit...... Also have no travel alarm if that helps Pj
Hi pj Possible stuck main relief valve ? I'd pull return filters and inspect.
Where is it at ?
Should be on main control valve. Not sure how valve is arranged but it should be separate from your line reliefs
It is a closed center load sensing system. It sounds like the hydraulic hoses are hooked up wrong. There was limited computer control on these machines so the hydraulics basically run the pump. I've run into the problem like this years ago when some pilot lines were hooked up wrong. Me and another guy got a book and checked the hookup of every line between the pumps and the main control valve. Found two lines swapped causing the issue. The owner of the machine spent thousands on the dealer who screwed it up the first time. The dealer never paid back a cent so there were no more Komatsu machines in their inventory after that. I checked my stuff and all I have are the code pages for a Dash 1 & 2. Your are welcome to that if you PM me.
I'm not too worried about the error codes as they are only present while the switches on the back of the right armrest are flipped..... However you have me really curious about the hydraulic routing now, any chance anyone has a schematic ? Pj
There appears to be main reliefs in the end caps of the main valve stack, but it would be odd for both of them to be malfunctioning? This is a fairly complex system even without a lot of computer control. If it was me I would have to get a manual first, try to understand what has to happen for everything to join hands and dance. There's electric pilot valves on the pumps, looks like four load sense lines?, Electronic pressure control valves, unloader valves in the main stack... Your comment about the lines getting hot sounds like the pumps are pushing oil somewhere, is the tank getting hot as well, and the suction side of the pump lines?
Yeah I agree that the pumps are pushing the oil someplace we just don't know where the cooler and tank return lines are not warm, there is one line on the bottom of the stack that gets hot like the pressure lines. The large suction line on bottom of pump is hot as well so somehow the fluid is getting back to the tank without running thru the cooler IMO Pj
I'd pull return filters and inspect it might give a lot of insight. possibly could be a tee shirt floating around.
Folow that other line that heats up, where is it going?
Can't rightfully tell I'm going to have to pull the side off the machine I'll get on it tomorrow or monday though Pj
Always good advice, start with filters, suction strainers, inspect inside of hyd tank looking for clues.
Okay Komatsu guys... what do all those solenoid valves on a manifold with an accumulator do? Looks like one each for track two speed and swing brake release? Looks like another one might connect to both end blocks on the main valve stack? I'm working off parts pages here, so I may be wrong.
Second stage relief, pilot lockout, merge-divide, travel junction to name a few more, Have you confirmed pilot pressure? 3-4 Mpa. Pump standby pressure? 3.6 mpa. What does gauge show for hyd temp? Hot by touch is very subjective, machine can be at 60 degrees C (140 f) which would feel hot, but is normal operating temps. Theese machine have an unloader valve and a main releif. In neutral when destroked all oil should be flowing out unloaded valve at standby pressure.
tell me more about the unloader and relief, where they at whats the troubleshoot etc. thanks for the input guys pj
Wild guess, it sounds like maybe one or both pumps are actually on stroke, but the unloaders never shift so all the oil is flowing around in a circle making heat. Odd though, unless I'm missing something all the return oil from the valve stack should flow through the cooler. Any chance this machine has a fast warmup feature or option? Just rambling, sorry.
The PC228 is a closed loop system and doesn't have an unload valve. Go back to the basics and start from the beginning: are the pumps turning? Crack a line on the pump while its running and see if oil comes out. Once you're sure the pumps are turning, check the pilot pressure. The self pressure reducing valve is a common failure on PC's. At the back of the control valve, near the top close to where the lines come in from the pump, you should see a smaller square block (approx. 4inx4in) held on with 4 allen head bolts. On the side of this block there should be a pressure tap pointing straight out the side. You should see about 30kg, this is the self-pressure reducing valve reading or basic pressure or pilot pressure, whatever you want to call it, and it feeds the solenoid bank. With out it, you've got nothing.
Hey PJ With this being a DOA machine should check suction stainers and return filters before trouble shooting. Oil starvation and contamination could be occuring during diagnosis causing effects on diagnosis and the check book. Lol good luck
Actually this is not a closed loop system at all. It is a closed center load sensing system. There is a load sensing valve which senses pressure going out to an implement when a valve is stroked. That pressure is felt at the controls on the pump which increase flow from the pump until there is approximately 300 PSI more pressure at the pump outlet that at the implement. Older systems also have a main relief valve operated when traveling or the power up button on the left control handle in the cab is pushed. In newer systems the load sense and main relief were incorporated in one cartridge. Basically you need a book and plenty of study to understand the system. I have been thing about this some at times though and I wonder if the out lethoses from the pumps are hooked to the wrong valves. Get a book or schematic and follow them out. Crossed hoses would mess up load sense function.
well that makes since why my older 228 sometimes has track power sometimes it does not the travel alarm sometimes works as well......they are probably both either working or not at the same time and i've never realized it,,,,,,, is that a poss ?? also on that old machine the left button is jacked up and the 2speed switch doesnt work, they have bypassed the electronic throttle..... i have had it for years never got around to straightening it out. pj
How is the electric throttle bypassed? Pull cable? If so, I bet it's a dog, there's no way for the engine to respond to pump load and it will bogg down.
Ya it's got a pull cable, it's got tons of power not a dog at all
When in neutral, When the pump is at minimum angle, ie little displacement, the pump still puts out roughly 10% of capacity for cooling and standby oil. This standby oil is relieved to an unset able 36 kg/cm2 out the unloader valve. When an LS signal is sensed, it acts with the 36 kg/cm2 spring so pressure can now build in the control valve. If you have an LS leak, the signal can become low. Example; 250 kg/cm2 needed for moving rock 200 kg/cm2 LS signal because of major LS leak. 36 kg/cm2 spring. 200+36 > 250 Pump pressure can crack that unloader valve and dump to tank rather than actuator. This is all really useless information if you don't have pilot pressure. The self pressure reducing valve likes to seize in these. There's a little coin filter in it that blows or plugs and sends shards into the spool. It's the thing that looks like a pack of cigarettes bolted to the control vale with 3 8mm hex bolts. Without pilot oil, your pumps won't stroke right and your joysticks are useless.
I just went back and re read this thread after working on the machine again today and it's got me confused again lol. Any new ideas ? I'm affraid we might have a bad pump, I pulled the epc valves and found traces of metal, the pump closest to the motor has a lot of pressure (not sure how much I didn't have my gauges hooked up) the pump farthest away has very little psi, infact I was able to hold my thumb over the test port with engine running Something else I thought was really interesting is that we took the bucket off of it yesterday and the boom and stick stayed in place, I hit the key fired right up and let the boom down nice and slow but it will not even come close to picking it back up, (that means we have electronics and pilot circut operating correctly right??) I then took the top off the filter housing and we have absolutely NO oil getting ran back thru it there is also no traces of any trash in the catch basket on the filter. New thoughts ? Thank you Pj
Being able to let the boom/stick down we have to have a good pressure reducing valve and pilot circuit ? If the main pump is bad why wouldn't one side of the pump at least try to operate some function ? Merge valve problem ?