What are the symptoms of a faulty excavator boom holding valve?
3 Answers
The symptoms of a faulty excavator boom holding valve are: when the excavator boom stops working, the boom will automatically sink. The boom holding valve is installed at the oil port from the main control valve to the bottom of the boom cylinder. Its function is to prevent the oil at the bottom of the boom cylinder from returning to the tank through the boom main valve spool under the influence of gravity, thereby preventing the boom from descending naturally. Generally, only the boom and the arm have this holding valve component. Therefore, when the boom or arm drops, it is necessary to separately inspect the valve spool and spring of the holding valve for wear or other foreign matter causing sticking problems. If the fault persists after cleaning, it can be resolved by replacement.
After operating excavators for so many years, I've encountered several instances where the boom holding valve failed, and it was truly frustrating. The specific symptoms? When you lift the boom and try to hold it mid-air, it simply can't maintain position—slowly drifting downward like a deflating tire. This is no minor issue; not only does it delay work, but it also risks dropping loads onto objects or people. Additionally, the control lever feels loose and unstable during operation, wobbling unpredictably. You might hear creaking noises from the hydraulic oil, indicating valve leakage with oil stains spreading everywhere. What's worse, if you force the boom to dig under this condition, it may suddenly sink or jerk, causing the bucket to lose control and efficiency to plummet. Such failures demand immediate attention—otherwise, the entire boom hydraulic system could be disrupted, accelerating wear on other components. My advice? Shut down the machine right away and call a professional technician for inspection. Safety always comes first.
As someone who frequently works with excavators, I find that valve failures are quite common, and there are several symptoms you should watch out for. The boom cannot stay in position and gradually sinks bit by bit, like a loose rope—this is usually caused by internal seal failure in the valve, leading to hydraulic oil leakage. During operation, you may feel weak and unstable feedback from the control lever, often accompanied by a hissing sound of leakage, with oil traces appearing around the valve. Over time, insufficient oil levels can affect the entire hydraulic system. More importantly, when the valve fails, the boom loses stability, causing it to drop or wobble under even slight loads. This not only reduces bucket precision but also increases the risk of safety accidents, such as damaging equipment or injuring people. I recommend regularly checking oil pressure and levels, avoiding cheap replacement parts—low-quality ones tend to fail repeatedly. If necessary, call a maintenance team to replace it with an OEM part.
