I have a Kx057-4 that is sometimes weak swinging with a load. I can keep trying it and it will sometimes seem to get it's power back and operate normally. Without a load it seems to operate fine. I've changed the hydraulic fluid, return filter,etc. Any ideas?
Hey aafadca: I've heard the most common causes of a weak slew (assuming you're working on flat ground) are: 1) clogged internal hydraulic filters, or 2) worn slew motor seals, or 3) low hydraulic pressure...or maybe some combination. I'm wondering how many hours are on your machine? Also, here are some thoughts taken from a troubleshooting guide that applies to our Kubota machines. I've got a similar excavator (Zero turn radius U55-4). Good luck. I hope it's not an expensive repair. Diagnosing a bad swing motor on a Kubota KX057-4 excavator involves distinguishing between hydraulic failure (weakness/slowdown) and mechanical failure (grinding/noise). A failing swing motor often shows reduced power, slow speed, excessive heat, or drift on slopes. Here is a systematic approach to diagnosing the swing motor: 1. Initial Inspection & Symptoms Check for External Leaks: Look for hydraulic fluid around the motor housing, particularly at the case drain line or the shaft seal (where the motor meets the gearbox). Observe Operation: Is the swing slow, jerky, or weak in one direction? Listen for Noise: Grinding or knocking noises often indicate mechanical issues in the gearbox or bearings. Perform a "Drift" Test: On a slight slope, swing the arm, stop, and hold the joystick in neutral. If the upper structure slowly drifts downhill, the motor's internal parking brake or relief valves are likely worn. Feel the Temperature: A failing motor will run excessively hot. 2. Testing Procedure Check Hydraulic Fluid: Check the hydraulic tank for low levels, milky fluid (water contamination), or a burnt smell. Inspect Filter: Remove the hydraulic return filter and check for metallic particles, which indicate internal wear of the motor or gearbox. Case Drain Flow Test (Definitive Motor Test): This test measures internal wear. Disconnect the case drain hose from the swing motor. Direct the hose into a container. Run the machine at idle and swing. If high volume oil comes out of the drain port while under load, it confirms high internal bypass, meaning the motor's internal seals are worn. Check Swing Relief Valve: Low pressure at the motor ports, checked with a pressure gauge while stalling the swing, may indicate a faulty swing relief valve rather than a dead motor. 3. Differentiating Motor vs. Other Components If ALL hydraulic functions are slow: The issue is likely the main pump or main relief valve. If ONLY the swing is slow: The issue is the swing motor, the swing relief valve, or the swing control valve. If the swing jerky or noisy, but has power: Focus on the swing gearbox and bearings. Common Causes of KX057 Swing Failure Internal Wear/Seal Failure: Causes low pressure, leading to slow swing. Contaminated Oil: Damages bearings and pistons. Loose Motor Bolts: Bolts connecting the motor to the gear reduction unit can loosen. Bad Woodruff Key: Play in the motor shaft-to-gear connection causes jerky motion. If the motor case is not overheating, check the hydraulic pump or control valve first, as they are often the source of slow speed.
Thanks for the info! It has about 3570 hours on it. I'll check these symptoms out next time I use it. From what I recall there's no grinding noise, no drift on a hill, it's not slow or weak without a load, it spins great! Just sometimes when im pulling/pushing something with good weight. Thanks again!
Let me know how you make out. I’m curious. My excavator has about 3k hours. I have a good relationship with a very experienced Kubota mechanic too. If you can’t solve your issue I’ll see what he has to say.
Will do. Thanks