Hi, new to this forum. I’ve got a Komatsu excavator pc58uu-3 2006 The machine will stall the engine when I use any of the boom functions, won’t stall when walking. This doesn’t happen all the time it seems to have almost no power most of the time but when it starts stalling it seems to have heaps of power, starts bucking around and no fine control. I’m suspecting it’s the piston main pump but wanted to know if anyone else has had this problem. I’m pretty sure it’s an issue on the hydraulic side, engine blows a bit of black smoke when it bogs down and stalls indicating fuel supply is good, im just curious why I have good flow and seemingly extra pressure when it’s malfunctioning. Any info would be helpful. Cheers
It sounds like you may have something intermittently hanging up which could possibly be from contamination. You should remove the hydraulic filter/s and inspect them for debris before you do anything else.
Hi Vetech63, I have replaced both main filter and strainer and two lots of hydraulic oil, no sign of anything so far. I spoke with Komatsu here but due to the fact the machine is an import here in Australia no one has had much to do with them. My instinct is saying the swash plate is jambing but I’m hoping someone has had the same symptoms and before I pull pump has had this happen and it was something else
Based on the above symptoms, I think your machine is faulty in the "BOOM INCREASE SPEED VALVE" or another name "BOOM ASSIST VALVE".
I'd be looking at a valve issue not your pump. I'd also check pilot pressure.
Lachau, how did you make those red lines on that drawing? I have not been able to change anything on a PDF and that would be so handy.
Paint program? SIS will do it now with interactive diagrams.
I have used the Adobe Acrobat ProDC software. Of course, you can download the free trial.
I'll definitely look into it today.