I purchased this machine a few months ago with these issues so I don't know the history of things leading up to these problems. It is a Mitsubishi mm55 ss. It has weak/slow hydraulic on allmost all functions. The tracks move but it will not zero turn , going up hill is a struggle and it seems like there isn't any power, the engine does not bog down or strain. The boom, crowd, and curl all work but if seam really weak but if you baby it it will dig. Again the engine does not bog down. Swing is slow and weak. Oddly enough the dozer blade seems really strong. It will easily lift up the machine. If you use the boom to lift the machine it struggles but you can get it to lift the machine, then the dozer blade will lift the other end fairly easy.... you can get the whole machine in the air if you try..... Now the oddball things. Someone changed out the electric hand controls for cable drive controls. The factory spools? Had both electric and the connections for cable.... I bet they screwed something up in the conversion..... the previous owner said he started messing with the adjustable ports on the spool valves and made the machine” better” he bought it to dig one job and was dun with the job when I bought it. The machine has 1600 hours a tad of white smoke when starting and its cold. Body isn't beat and undercarriage seems pretty decent so I don't think it had a crazy hard life... So I'm pretty comfortable with most all auto and diesel repairs. Complete engine and tranny rebuilds are under my belt. But I just am a little unfamiliar with hydraulic diagnastics. So please be gentle on me, and over explain what I need to test and what my readings should be. And most importantly where to start for a dummy like me... Thanks in advance for your input...
hey wayne whats the serial #.... and is the blade circuit also cable controlled?
First and one of the easiest to do would put a pressure gauge on one of the weak circuits to view the maximum pressure. If the pressure hits say 3000psi immediately you probably have a control problem with the spools not opening all the way. If it takes awhile and only hits say half that you have a pump problem. Either the pump has major internal leakage (worn out), the swash plates arent stroking (servo piston stuck or damaged) or you have a restriction feeding into the pump
Serial is e1g00525 and yes cable driven now I can't seem to get the center swivel out of the bottom
??? why would you take the swivel out??
I had read on another thread that the center swivel was a common problem and that it was easy to pull apart and reseal. So it was something I was gonna try.... So on my bank of spools, pick a weak circuit, Does it matter what hose I take off? And attach the gauge to the spool output side correct? (replacing the hose with the gauge) Do I have to cap the hose off? So I see the 3 ports coming off the 2 different section of the pump. 2 T's inline with the hose in the first pump section and 1 on the smaller pump. Should I hook up a gauge up there? What psi should I be getting? All the same psi? I dis check some of the small silly things today such as both tank filters. And I did drain off some from the tank. The previous owner stated he had changed the fluids and filters, which were all very clean so it appears he did. Any special fluid I should be getting to top off what I have drained off today? Or just hydraulic fluid
Yes, that is true, but you dont have a problem with just the lower machine. You have a problem with the whole machine. I think the easiest point would be one of the hoses going to one of the cylinders
I was figuring that of course the output hose would be weak... Other wise I should have good power, right? Unless all cylinders and wheel motors are bad.... what about the reliefs on the front and back of the spools? again the previous owner said he had turned them and made it "better" I have to admit I tried turning a set of them in also and it did help a tiny bit. But I stopped since I knew I should be using a gauge.... Is there a " main relief" that may be weak? Thanks for the input.
There maybe a main relief external to the pump. I would put the gauge on one of the boom hoses or what not and go from there
hey wayne... that serial number you gave me is for a plate compactor? If you can look again, it should be at the base of the boom infront of the cab. I dont think there is any need to tee into any hoses... Im pretty sure there is test ports on the main pump to check main relief pressure. (I just looked it up using a random serial#. Looks like there is 3 different main releifs ... main releif #3 is for your boom swing, swing and blade (*on the random serial# im using*)... so if your machine is anything like the one im looking at you know your blade is working "ok" but the rest of the circuits arent... this tells me either your pilot control cables arent proberly adjusted, and or line reileifs are set way to low. Take a look on top of your pump for 3 pressure taps. The one furthest away from the engine is for main reilef #3. Hook a 5000psi gauge up to it... get hyd oil warm. Then stall out your blade circut in both directions. You should see around 3500psi... if you do see 3500psi you know your line reilefs are set and working fine.. then swap one of your blade line releifs with a line releif from another circuit (just pick an easy one to get to). If the fuction you swap it with now works fine you know your problem more then likely is just line reliefs that need set up. If it doesnt fix the problem then you know its more then likely your pilot cables need adjusted. Hope that helps! try and get that serial# for more info!
Serial # E1G00523. OOPS
Made good headway today. So all 3 ports off the pumps instantly jump to a little over 3000 psi instantly. Then over 4000 psi. Near instantly. So that seems all good and I process.... Then I pull off one of the weak circuits hoses and hook a gauge to the spool and cap the loose hose end,,,, it shows 3000 when you hit that lever.... so I thought that was odd and didn't make much sense.... So we started Marking all the lines and tracing all the lines going to the spool bank. And there was one that came from the main pump to the middle of the spool bank. this line had a relief valve in its spool block and as we were tracing the line it just made sense that something was off in the circuit... so I pulled that relief out and took a closer look. No debris, but the Allen screw was only in about 1/2 a turn from making contact with the spring..... so I tightened the Allen in 2 full turns. Then I put the relief back in and fired her up........ and she has tons more power on the hydraulics... sweet... We took it for a quick trial run and the track have tons of power. It Will zero turn in mud and pavement. You can use the boom and drag the tracks on the machine with the dozer blade up. All good Now it still needs tweaking, the curl has power but seems slow..... the house swing is still a little weak and you can hear it bypassing in a squealing noise. So that needs adjusting.... So now I want to go through and adjust and properly set every relief valve on the spool bank.. cause I know the previous owner messed with some of them, and others are obviously wrong.... what's the best way of doing that? What is the target psi? Should I be hearing the "squealing" when the relief bypasses? Getting closer Thanks
I think the squeeling is the line relief valves, they are usually more than the main and shouldn't blow when using the circuits, they should only blow off in hold when something hits the machine and forces a cyl. They are to prevent machine dammage from external forces. When you find the spec's adjust the main higher than the spec and then set them by loading the circuits with throttle at low idle. This will work if you can't get the procedure from the manual. Later Bob
Is the main relief on the bank of spoils? Just the one without a circuit? I think so but not really sure...
I think so, the line relief's are by each spool valve, onr on top one on bottom. Later Bob
Engine compartment (1) Pressure tap (P1) (2) Pressure tap (P2) (3) Pressure tap (P3) Open the engine hood in order to access the pressure taps for the main relief valves. Connect a 40000 kPa (5800 psi) pressure gauge to pressure tap (1) . Connect a 40000 kPa (5800 psi) pressure gauge to pressure tap (2) . Connect a 40000 kPa (5800 psi) pressure gauge to pressure tap (3) . Start the engine. Increase the engine speed to high idle. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F). To check the main relief valve pressure setting at pressure tap (1), move the joystick for the bucket until the bucket is at the full BUCKET CLOSE position (full extension of bucket cylinder). Hold the joystick for the bucket in this position. Check the pressure on the pressure gauge at pressure tap (1) . The pressure should be 24500 +1500/(-0) kPa (3553 +218/(-0) psi). If the pressure is not within the specification, refer to "Adjustment (P1)" for the adjustment procedure. To check the main relief valve pressure setting at pressure tap (2), move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of the stick cylinder). Hold the joystick for the stick in this position. Check the pressure on the pressure gauge at pressure tap (2) . The pressure should be 24500 +1500/(-0) kPa (3553 +218/(-0) psi). If the pressure is not within the specification, refer to "Adjustment (P2)" for the adjustment procedure. To check the main relief valve pressure setting at pressure tap (3), move the boom swing control to the SWING LEFT position and hold. Make a note of the reading on the gauge attached to pressure tap (3) . The pressure should be 24500 +1500/(-0) kPa (3553 +218/(-0) psi). If the pressure is not within the specification, refer to "Adjustment (P3)" for the adjustment procedure. Return the engine to low idle. Stop the engine.
hey wayne... that serial number is still wrong, the 5 numbers at the end are not as important as the first 3 letters? the 3 letters (prefix) you gave me is for a plate compactor? Anyways there is the proper way to check all 3 of your main releifs using a DSA prefix, and i still dont know if yours has 3 or just 1 or whatever (until we get the right serial#)... turning that releif screw in 2 full turns is kind of sketchy... you really have no idea how much your pump is putting out now? you may be putting out 5000psi!! things will break!!! like bob has said... your line releifs only work to protect a circut from overload...they really never do anything, your main releifs do all the work. (for example a pit loader is digging into a big undercut bank, the bank caves and all the dirt falls/drops into the bucket of the loader, the bucket curl circuit would probably go into *line releif*, to protect from exploding the cyl/lines ect.....that being said, your line releifs are set higher then your mains. you should probably get your mains set up first to be safe that your not putting out exessive pressure right now. then to set your line releifs you actually set your mains higher then your line reliefs.(so your going over line releif instead of main) then check them buy stalling out each circut. adjust them accordingly to spec. they are usually set just a couple hundred psi higher then main. I will post the procedure for setting the line releifs. Just keep in mind that this is a random serial# i am using for a 305c excavtor..
Top view of main control valve (4) Line relief valve (bucket cylinder head end) (5) Line relief valve (boom cylinder rod end) (6) Line relief valve (boom head) (7) Line relief valve (stick cylinder head end) (8) Line relief valve (stick cylinder rod end) Relief Valve (Line) - Test and Adjust Test Procedure Before you perform these procedures, refer to Testing and Adjusting, "Machine Preparation" for the proper procedure to prepare the machine. Note: The following tests require operating the engine at high idle. Refer to Testing and Adjusting, "Engine Performance - Test". Note: A temporary setting of the main relief valve is required before any line relief valve can be tested. Temporarily adjust main relief valve (P1) in order to test the boom line relief valves and the bucket line relief valve. Temporarily adjust main relief valve (P2) in order to test the stick line relief valves. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust". Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the proper procedure. Engine compartment (1) Pressure tap (P1) (2) Pressure tap (P2) (3) Pressure tap (P3) Open the engine hood in order to access the pressure taps for the main relief valves. Connect a 40000 kPa (5800 psi) pressure gauge to pressure tap (1) . Connect a 40000 kPa (5800 psi) pressure gauge to pressure tap (2) . Start the engine. Be sure that the engine is at high idle. Move the bucket's control lever to the CLOSE position and hold. Make a note of the reading on the gauge attached to pressure tap (1) . The pressure should be 27900 ± 1500 kPa (4050 ± 220 psi). Move the boom's control lever forward to the LOWER position and hold. Make a note of the reading on the gauge attached to the pressure tap (1) . The pressure should be 27900 ± 1500 kPa (4050 ± 220 psi). Move the stick's control lever forward to the OUT position and hold. Make a note of the reading on the gauge attached to pressure tap (2) . The pressure should be 27900 ± 1500 kPa (4050 ± 220 psi). Move the stick's control lever backward to the IN position and hold. Make a note of the reading on the gauge attached to the pressure tap (2) . The pressure should be 27900 ± 1500 kPa (4050 ± 220 psi). If any of the pressure readings are not set to the correct specifications, adjustment of that line relief valve is necessary. Refer to the "Adjustment Procedure". Note: Always make final pressure adjustment on pressure rise. Note: Adjust the main relief valve to the specifications. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".
hope that helps wayne!.... be careful and good luck!
Jake, I will check it again. My ID plate is really pitted and smashed up from rock damage and being banged around. That info defiantly gets me going on the proper procedure to set things up. Yeah I know that turning it in 2 turns is a horrible way to adjust things, I was just really happy to identify the problem (I think at least). A huge Thanks for all your input and info. I will be able to mess with it tomorrow hopefully and will report back with my findings.
Ok looks like the serial is DSA. Just a 305. I had to order some parts and this prefix got me what I needed... Jake I started going through the procedure and mine is a little different than what you posted earlier but it is close. The instructions you posted say to "refer to testing and adjusting procedure" relief valve, main etc... Can you post that as well? Just so I can make sure I'm doing it right? I think I'm little cloudy on some of the details. I get the 3 main ports in the engine comp. But when I'm doing the line reliefs off the spools does it matter which line of the circuit I tap? Do just un hook a line say "boom" put my gauge on the spool side where I just unhooked my line then put a plug in my loose hyd hose and run my lever on that function fully til I get my reading? This is my first time setting any psi up like this and I just want to make sure I'm doing it right.... Thanks again
Ok, I have ran through the main relief pressure and got them set. Nothing was too crazy. But on the smaller pump line#3 that runs blade, house swing, boom offset . The psi is set fine for me but it makes a loud squalling noise....(it always has made a noise on me) only these circuits do this.... It will even make the noise in motion, for example if I offset the boom it makes a squalling noise while the boom is moving, then when it goes to full stroke the squalling gets louder. So something is up with this "circuit". Also my spool is a little different set up than the one posted. Where #3 comes in there is a relief on the front and back of that block. The front one controls the psi at the port #3 at the smaller pump in the engine bay. The back one doesn't seem to affect the psi...... What am I missing? Help
Hey wayne does the noise sound like its coming from the pump or control valve? Try cutting your hyd filters and checking for debris....to get you the right info I need the correct serial number for your machine... See if you can get the serial number off the engine, I should be able to get it that way...
The sound/vibration seems like is coming from the spools right where the #3pump line comes in.. but not at the #3pump in the engine bay... . I swapped the relief from #2 same noise... There is another relief on the back side of this spool also? It is different than the other 3.. it is a square rather than the 1 1/16 wrench to get it out... the line below this "relief" goes directly to the tank and Not through the cooler and filter side like the other returns.... I don't understand what this one does.... I have looked and looked. And I can not find any other serial numbers nothing on the valve cover that I can find.... can you please post a couple more random serial # setups on the spool valve set up and flow chart? They looked up a cat 305 DSA serial # to get me the correct engine injectors, I messed with this thing all day today and no luck. I am really banging my head . Thanks