Good morning, I'm having a hydraulic issue with my 138-8. All functions slow right down, if i open another valve it will speed up again. Have checked pilot pressures. They are normal until it slows down. Any suggestions on what I should check ? Am guessing it could be something before it goes to the valves because its not just one valve doing this. Machine only has 3800 hours. This problem just started suddenly. Thank you for any help with this matter
Do you know if there are any fault codes in the monitor panel. Do you know how to get into the diagnostics menu for the machine?
Good afternoon, no codes. I've had a mechanic come to see machine and check pressures. He did check the panel. Thinking it could be main control valve. Just wondering if anyone has seen this problem. Thank you
How many hours do you have on the machine?
3700
Sorry I missed that in your original post. Let me restate how I interpret your problem. Operating one thing at a time, each function is slow. Operating any function and then another function and then the speed of both functions are normal. Is that correct? I would probably operate each function one at a time and then add another function one at a time looking to see if a combination of two functions didn't change anything, things were still slow. The other question concerns the function of the travel. Does the problem also happen with operation of one track at a time? Does the machine walk straight in all speed ranges? One other question concerns the auto decal on the engine. Does the engine speed up when operating a function?
Good morning, I've noticed this on all functions including the travel. If the swing slows down and I pull up on the boom it does speed up again until it happens again which is within seconds. Tried in power mode, which also happens but not as bad as attachment default. (Has a thumb). The machine did run low on hydraulic oil. Am guessing that is the cause of this. The engine speed is normal. Auto decal working as it should. Thank you for any help
Are you saying the functions speed up for a few seconds and both slow down or that things work normally for a time after operating the boom up? The latest of the closed center machines I've had hands on were Dash 6 models and I'm not sure what has changed between those and the Dash 8 models. The problems sounds similar to what I experience on the Dash 6 models. There are load sense and separate pressure control valve cartridges on the pump. As I recall one of those has a hose connecting it to the main control valve, usually a #4 fitting connection. I used to tee into that connection to read the load sense pressure that the pump was seeing. It should be somewhere around 300 PSI lower that the main pressure coming out of the pump. If that was correct, I would remove that cartridge from the pump casing and take it apart, clean all the parts with ether and then reassemble it and reinstall it. Sometimes that worked. It does sound like a problem in the load sense part of the hydraulic system.
Great thank you, I'm going to tell the komatsu tech on Monday when he comes by. Hopefully this will get resolved soon.
Dismount the pressure reducing valve, there is a fine mesh strainer mounted on the half, you have to check it is clear from dirt , make sure the reducing valve piston has smooth movement along its stroke, it is sometimes jammed due to dirt I might be wrong , but i encountered many of such symptoms , i deal with alot of komatsu unit dash 5 to 8, If you maintain good regular change in oil and filter, the main control valve or mainpump are usually out of issue until at least ten thousand hours Most of the issue is only clogging strainer on main pump solenoid, or pressure reducing valve malfunction I have the manual, just in case if you need it for reference
Dismount the pressure reducing valve, there is a fine mesh strainer mounted on the half, you have to check it is clear from dirt , make sure the reducing valve piston has smooth movement along its stroke, it is sometimes jammed due to dirt I might be wrong , but i encountered many of such symptoms , i deal with alot of komatsu unit dash 5 to 8, If you maintain good regular change in oil and filter, the main control valve or mainpump are usually out of issue until at least ten thousand hours Most of the issue is only clogging strainer on main pump solenoid, or pressure reducing valve malfunction I have the manual, just in case if you need it for reference
Thank you, I'll tell the komatsu tech this tomorrow morning
hi chris, i have same problem what did this end up being?