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safety suction valve, arm and boom check valve, Komatsu Pc220Lc-6L
- Thread starter Jon_one
- Start date
Jon_one
Well-Known Member
yes it is .. more updates to the problem , when you slightly pull in the stick the weak track gets all the power in the world ... and u hear the pump stroke up . with the track lever alone on the weak side the pump doesnt stoke up . any one function on that pump and it doesnt stroke up .
when you merge the two pumps machine works almost normal besides the weak track .
i am going to try tracing all lines to make sure all are in correct places and work my way up from there ..
adjusting LS valve on pump or tvc valve on pump creates no change . i believe it is a control valve issue because when i switched the main pump lines and the LS lines that were crossed the problem switched sides ..
when you merge the two pumps machine works almost normal besides the weak track .
i am going to try tracing all lines to make sure all are in correct places and work my way up from there ..
adjusting LS valve on pump or tvc valve on pump creates no change . i believe it is a control valve issue because when i switched the main pump lines and the LS lines that were crossed the problem switched sides ..
Jon_one
Well-Known Member
ok so i dont know if this is related to the problem but a hissing noise is always heard from the control valve .. no matter the position of safety lever . it is loud enough to hear with the machine revving at high idle .. i dont know what is by passing where .. it is hard to pin point but definitely coming from control valve . i thought about the swivel but it does not sound like it is coming from there ..
this sound is heard while evrything is at neutral . i have not checked for the noise whilst operating functions . i will do this tomorrow .
i was thinking that i can try disabling (i am not sure how) the Pilot Pressure control pump to rule out any Pilot pressure issues ..
this sound is heard while evrything is at neutral . i have not checked for the noise whilst operating functions . i will do this tomorrow .
i was thinking that i can try disabling (i am not sure how) the Pilot Pressure control pump to rule out any Pilot pressure issues ..
Hydraumind
Well-Known Member
Hissing noise is normal, it is oil flow being unload to tank. You can check other machines and hear the same
rmllarue91
Senior Member
Second hydraumind work on a pc400 and has always had same hissing. Does this machine have ppc shuttle valve?
Jon_one
Well-Known Member
yes it does
Jon_one
Well-Known Member
so what can cause the track to speed up when the stick is pulled in slightly ? very noticeable speed difference in weak track (front pump) .. and very slight difference in other track (rear pump)
The weak track barely builds pressure , the better track almost reaches relief pressure (260-280kg/cm2)
The weak track barely builds pressure , the better track almost reaches relief pressure (260-280kg/cm2)
Jon_one
Well-Known Member
i will do this today . but i can tell you that the weak track has a cycle time of over a minute ..
but the weak track and arm are on the same circuit .. would this be a merge situation also ? and will the merge affect travel speed ? and if i pull in the lever right in it would not work no other function makes the track spin faster other than just slightly pulling in the arm lever like one inch . if i pull it more than this the track will sort of jerk fast slow fast slow .. any more than this and no change .
but the weak track and arm are on the same circuit .. would this be a merge situation also ? and will the merge affect travel speed ? and if i pull in the lever right in it would not work no other function makes the track spin faster other than just slightly pulling in the arm lever like one inch . if i pull it more than this the track will sort of jerk fast slow fast slow .. any more than this and no change .
John C.
Senior Member
What mode do you have the machine in when you are running these tests? The computer has a logic to it that gives the best operating characteristics depending on the mode selected by the operator. You should be in the GO or HO modes when doing these tests. Are you aware that there is a straight travel valve that allows joined flow between the travel motors when the machine is traveling straight? If your travel is drifting to one side I would suggest checking case drain flow on the slow travel side. If that is good, I would check out out the swivel next.
The other issue is whether or not the weak travel side is sending a load sense signal to the pump to stroke up. Depending on machine mode the arm is a two pump function so using it while engaging the weak travel will cause both pumps to stroke up and the merge valve to open. Is it possible to check the LS Differential pressure for the travel by itself and the arm by itself? That might tell you if enough pressure is felt on the LS line to get the pump to stroke up. I would think you could have compensator leak on the travel is that is the case.
All this points to the reason I got to not like working the Dash 6 line. They are just too complicated a system just to move some dirt around. They are great when they work properly. They are time consuming and expensive to have to fix when something goes wrong and nobody at the factory level will share any information on how to find and fix the problems.
The other issue is whether or not the weak travel side is sending a load sense signal to the pump to stroke up. Depending on machine mode the arm is a two pump function so using it while engaging the weak travel will cause both pumps to stroke up and the merge valve to open. Is it possible to check the LS Differential pressure for the travel by itself and the arm by itself? That might tell you if enough pressure is felt on the LS line to get the pump to stroke up. I would think you could have compensator leak on the travel is that is the case.
All this points to the reason I got to not like working the Dash 6 line. They are just too complicated a system just to move some dirt around. They are great when they work properly. They are time consuming and expensive to have to fix when something goes wrong and nobody at the factory level will share any information on how to find and fix the problems.
Jon_one
Well-Known Member
ok for starters everything associated with that pump with the pumps split is slow . not so weak . tests are always carried out in H/O mode
so i am talking about arm , LH track and swing .. they are all slow . it was the other way around before i switched the LS lines and Pump lines . meaning that everything associated with the rear pump was weak before Boom , RH tack and bucket . so i am thinking that it is something associated with the LS system..
when the pumps are split and i pull in the stick just a little the track spins faster . pumps stay split based on my readings on codes 11 and 12 ...
when the pumps are merged the arm is faster and stronger . and swing is faster . the track remains the same .
The funny thing is both the LS lines and main pump lines were in the wrong places . when i switched them the problem went from one side to the next .. so i dont know if its a pump tvc ls valve issue or control valve issue . what i can probably do is swap the LS lines and see if i get any change ? i am confused here now ..
on your last point about the track sending a ls signal . i doubt very much that any of those functions are sending a LS signal . because the pump never strokes up .. what can i do to check this ? point me in the right direction to check thoroughly the entire LS system . all places to check .. i did change the LS shuttle valves so i may rule those out ...
John C.
Senior Member
You need a differential pressure gauge or two accurate gauges to check the LS differential pressure. Two gauges are installed on the pump outlets and to more gauges are installed on the LS ports on the pumps. When you operate a function the LS pressures should read somewhat less than the pump pressures. That difference was somewhere around 300 PSI as I recall. I has been some years since I've had to check this so I don't recall exactly the procedure but I know it is in the service manual. You can likely just plug into the LS port to see if you get any pressure at all. I would also suggest scoping the book out close and make sure you have all the hoses hooked up in the right place. It is a pain trying to follow the hydraulic schematic and then tracing the hoses from end to end but it sounds to me like that is what you are going to have to do.
Good Luck
Good Luck
Jon_one
Well-Known Member
ok i will do this . just have to make two more hoses and one more gauge
Jon_one
Well-Known Member
ok so i found an error that me and my service manual made .. i have two different service manuals and the two of them have the main pump lines going to control valve marked in different places . it looks like one had an error . so i need to switch my main pump lines back to normal . the LS lines were in the wrong place for sure ..
the two manuals in question was one specifically for my pc220lc-6 (the correct one i think) and the other from pc200-250lc-6
Jon_one
Well-Known Member
if any one can shed some light on this for me because it seems like some are mounted opposite or maybe it is an error . i will try mounting the other way and see if i get any results ?
Maybe this explains why the front pump was not stroking up when it was suppose to .
Maybe this explains why the front pump was not stroking up when it was suppose to .
Jon_one
Well-Known Member
ok so i switched the main pump lines and the problem switched sides . so now all along i thought it was the front pump that was not stroking up when the reality is because the lines were not on correct it is the rear pump that is not stroking as it should ..
tomorrow i am going to do a Differential pressure test . i should have all my fittings etc by then .. the front pump is working good now for arm etc .. the tracking issue switched sides ..
so i guess this problem lies in either the TVC valve or LS system for that side ...
John C.
Senior Member
I think there are different books for a serial number break. My book had PC200LC-6 for serial 80001 and up. There is a serial number break starting at 88000 and up. It has PC220LC-6 for serial number 50001 and up. There is a serial number break at 52000 and up.
What is the serial number of your machine? I am aware of three different hydraulic setups for the PC200-6 models that had different pumps and valves. Early machines had the LS valve cartridge mounted in the valve while later machines mounted the LS valve on the pump itself.
Nice job of following the book and chasing lines out. I would also suggest checked the pilot lines for the straight travel valve as well.
Good Luck
What is the serial number of your machine? I am aware of three different hydraulic setups for the PC200-6 models that had different pumps and valves. Early machines had the LS valve cartridge mounted in the valve while later machines mounted the LS valve on the pump itself.
Nice job of following the book and chasing lines out. I would also suggest checked the pilot lines for the straight travel valve as well.
Good Luck
Jon_one
Well-Known Member
John C.
Senior Member
According to my book you have the earlier version and the L after the 6 in the model number means the machine was built in Lexington, Kentucky. The LS valves for your machine I think are mounted in the valve block and not on the pumps. It has been a long time so I don't remember for sure. My book is the usual Komatsu with lousy illustration about where the cartridges are but I seem to remember having a bunch of trouble on the later machines where the LS cartridges were on the pump.
What I'm thinking about after you confirm all the lines are in the right places is to switch the LS cartridge valves and see if the problem switches pumps. It probably won't matter at that point if they are on the pumps or the valve blocks but I would like to know.
John
What I'm thinking about after you confirm all the lines are in the right places is to switch the LS cartridge valves and see if the problem switches pumps. It probably won't matter at that point if they are on the pumps or the valve blocks but I would like to know.
John
Jon_one
Well-Known Member
based on what i see and also my book , the LS valves are on the same place as the TVC valves which is on the pump mounted as one unit .
i do have two spare units lying somewhere around . i will do a Differential pressure test , try adjusting and if no change i will swap the ls valve on the problem side . i know it is not a control valve issue now because the problem did switch sides when i swapped main pump lines .
i also did try adjusting the LS valve pressure blindly with no gauge a few turns up and a few turns down just to see if i get any change and it made very little difference ..
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