Hello, I am seeking assistance with repairing our LULL. The machine in question is a 2003 1044C-54 Serial 18942 with 3700 hours of use (it was left outside for a period of time). Upon cold start-up, we are experiencing slow and limited hydraulic function. The boom moves up slowly and increasing the engine's RPMS causes the hydraulic pressure to cut out until the engine is idled again. The frame tilt is also very poor, with minimal movement when the lever is engaged. This issue seems to improve as the machine warms up, though it has become more problematic during the winter months. During testing, we observed 460 psi on the pilot circuit, which remains steady whether the engine is idling or revving up. Bottoming out a hydraulic lever results in 2800 lbs of pump pressure. When lifting the boom, the pressure reads around 1600 psi and drops off quickly when the engine is revved. We have checked the high-pressure filter and found no restrictions. The next point in the pilot lines is the selector valve, which directs the fluid to the control manifold. There are 2 coils on the selector valve. We recall a previous post mentioning similar issues and suggesting to check the coils for resistance as they are a common problem. Any suggestions on where to check for pilot pressure next? Should we focus on the selector valve or the control manifold? Any assistance would be greatly appreciated.
It appears that the pump may be experiencing oil starvation due to potential issues such as a clogged screen, collapsed inner liner in a hose, incorrect oil viscosity, or a saturated suction side filter. Is the pump possibly drawing air through the shaft seal?
We thoroughly cleaned the suction and return filters, which resulted in optimal performance throughout the day. Surprisingly, the filters didn't appear too dirty, but even a slight buildup can restrict flow and cause issues. It's important to keep these filters clean to prevent cold-related problems. Thank you for your attention to maintenance!
Answer: Answer: The slow boom movement and poor frame tilt could be due to issues with the hydraulic system, such as low hydraulic pressure, restricted flow, or faulty components like the selector valve or coils.
Answer: Answer: To troubleshoot slow hydraulic function, you can check the pilot circuit pressure, inspect the high-pressure filter for restrictions, and test components like the selector valve and coils for proper functioning and resistance.
Answer: Answer: If hydraulic pressure cuts out when the engine's RPM is increased, it could indicate a problem with the hydraulic system's response to engine speed changes. Checking components like the selector valve and control manifold for issues or restrictions may help diagnose and resolve the problem.
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