Hello to all of you, I'm glad to join this forum, I'm a recent owner of a 2.7 ton Komatsu excavator for my personnal use. I'm having good mechanical and electrical skills but I have an issue right now that I can't figure out. I hope someone can help me with it. Here is a short story about my issue: Last fall I bought a PC27R8 excavator model 1997 serial A11472 with about 4000 hours on it. It needed a lot of maintenance and some love (previous owner did not take good care of it) but everything was working properly. I parked it for the winter and did some repairs during spring : replaced 2 leaking hydraulic hoses, adjusted the control levers free play, replaced engine air filter, added some hydraulic oil in the tank, replaced the battery, inspected the console internal wiring in order to find why the BAT lamp was steady "ON" - Found a blown 20A fuse that I replaced and since then the alarm buzzer beeps every 5 seconds so I removed the fuse because I didn't have the proper wiring diagram on hand to find the electrical issue. After all this work, I tried to move it out of it's winter storage location: the engine started and run fine but no hydraulic function is working, it's like if a safety interlock was on. No abnormal noise from pump. I checked the safety levers mecanism and it is linked by a mechanical cable to a control valve lever mounted on top of the main hydraulic body valve and it seems to be working properly and well adjusted. I removed the mechanical cable and moved the control valve lever manually from one end to the other without any change. I tried everything I could to find what is hapenning without success. I really don't know were to start and what to look at since the service manual I found is for newer models starting at serial F31103 and up. The hydraulic and wiring diagrams looks different from what I can see in my excavator, so I cannot really rely on it to help me find the issue. Do you have an idea of what could cause this issue ? Do you know were I could find the right service manual for this old machine ? Any help you could provide will be very much appreciated, I really don't know where to look at. Thank you, Dany
Is there someone in this group having access to a PC27R8 excavator serial A11472 service manual ?
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I had a loader have a similar issue one day, the hydraulic functions weren't working at all and we ended up bleeding air out of the lines going to the pilot controls in several places. That machine usually does it after replacing a line but that time it was out of the blue one day. If you have a way to verify the pump is turning I would start with that to make sure you don't have a coupler issue.
This manual is for a newer model, I already have a copy of it. Thanks
Could have been, but no. I found the issue: I first looked into the oil tank filling cap for oil flow coming back of the oil return line (oil filter unit line): no oil flow at all. Then I knew it was related to the pump. I thought air got trapped into the hydraulic pump so I opened the purge nipple on top of the pump when engine was idling until some oil went out and voilà !! It was alive.
That’s exactly what happened, bleeded the pump and it came back to life. Problem fixed