Hey everyone I have a question. For the past two weeks I have been tracing leaks testing pressures and haven’t found the issue with the boom up or even an explanation as to why it is the only function to move slow. I tested pump pressures from this machine to a working one and I see the pressure is about 700PSI lower on this machine. It works fine when the two pumps are separated. It acts as if the ahi side for the boom up is not engaging with both pumps merged together. Current boom up time is 26 seconds in high idle. Half idle it is 16 seconds. Originally I followed the steps the book said to follow and haven’t seen anything wrong with the book valves. The only one I haven’t pulled is the Merge/Divide valve. I did test it to make sure it was working. What would the next step be to test?
You should determine if the problem is hydraulic or electrical before going any further. I would suggest going into the monitor panel and checking for fault codes. You can also check all the switches and sensors from the monitor.
There are no electrical fault codes. The pressure switches are reading. The solenoids are showing to be activating through the monitoring screen
What do you have for pilot pressure? How many hours do you have on your machine? Does the boom up speed change if you move one of the tracks at the same time?
Pilot pressures are 500-600PSI depending on the function, hours are 6445, and yes the boom speed increases to normal speed the moment you slightly engage one of the tracks
There is one function I have 0 pilot pressure on and that is the swing left function
I'm not sure on your machine but usually pilot pressures are supposed to be around 300 PSI and I usually see them around 400 when the machine is at full throttle. Have you pulled the return filter or the suction strainer.
Yes I replaced both of them since they were dirty and hadn’t been replaced in about 2000 hours. Give me a few and I will give you the list of pilot pressures per function.
PSI rating for each function Boom Up-550 PSI- Book says 512PSI Boom Lower- 650PSI-Book says Lo-270PSI Hi-469PSI Arm Dig-600PSI- Book says 512PSI Arm Dump- 750PSI- Book says 512PSI Bucket Dig- 600PSI- Book says 512PSI Bucket Dump-600PSI- Book says 512PSI Swing Left-600PSI- Book says 440PSI Swing Right-600PSI- Book says 440PSI
Are those pilot pressure ratings? I've never seen a Komatsu book state a pilot pressure rating for each function before. They gave a standard pilot regulator rating of 425 PSI.
This is what I am going off of. I couldn’t find anywhere where it specifically talks about Pilot Pressure
Control circuit source pressure is stated at 33 kilograms per centimeter squared which comes out to about 470 PSI.
I don't understand where your readings are from?
I was reading them off of the boom, arm, and bucket
Right above it it says boom then next to it it says raise and then it says kgf/cm2 then moves over to 34.81. So I thought with where you test the pilot pressure for the spool caps that’s what it meant
I'm not familiar with those lower readings but I'm guessing those are control pressures between the main control valve and the pump itself. They are not the pressures that move the spools on the main control valve. I'd have to do some studying in the service manual to figure out what they are saying. I'll check and see what I have in my library about Dash 7 systems.
Alright. I really do appreciate the help you are giving me.
What is your serial number? 3 individual shop manuals for the different serial number ranges.
A86369 is the serial
Have you changed your pilot control filter? I had similar problem.
I have not. I didn’t even know it had one. Where would it be located at?
I've never seen on a Komatsu.