Hi, I've got a 2008 Caterpillar 305C-CR with about 4200 hours on it. Got it about 6 months ago. When I started working with it during spring, I was lifting big rocks with no issues. During summer, the boom cylinder has been rebuild (new seals, new rod) by a shop supposedly very very good in this. Since the rebuilt cylinder has been installed, I've noticed a loss of power. The same rocks I lifted like marshmallow before (rocks of about 4,000 lbs) seem out of reach, looks like the relief valve kicks in quickly. What could cause this? Thanks!
The times when I have noticed this it is always the fuel filter. I am not sure if your machine simply wont lift, or the engine sounds like it is bogging down. If the rpms stay constant then I would say the relief had been messed with. Not sure why someone would do that for that type of repair. Perhaps replacing the hyd. filter would be a good place to start assuming the engine is maintaining rpm.
Hi KSSS, Thanks for your reply. I forgot to say a few things. At the same time the boom's cylinder was replace, the guy also replace the fuel filter and the oil filter. The are not genuine Cat part but "will fit". The engine does not bog down when I'm trying to lift a big rock. Engine doesn't blink at all. Also, when we tried to identify/isolate the boom's cylinder problem, the guy swapped the boom relieve's valve with the ones for the undercarriage. But the guy numbered everything and I checked this morning and he did put everything in place. So I guess it leaves me with a dirty hydraulic filter? Thanks,
I would try that. Next would be to see that all the reliefs are set correct.
Hi KSSS, Thanks again for your answer. I'll order a hydraulic oil filter this week from CAT and find instructions on changing it for my machine. Is possible that the relief valves' settings were changed when a swap test was done? I don't know too much about how to set them properly but is it possible that their settings were altered by mistake just by swapping them? Thanks,
I don't know how easy it would be to alter the settings by mistake, but I do know that certain functions require different relief settings. The boom cylinder valve will be set different than say the aux. circuit in its relief setting.