What Causes Exhaust Brake Failure?
3 Answers
Exhaust brake failure can be attributed to hardware damage in the EVB exhaust pipe, such as broken bracket plates, fractured cylinder push rods, detached bracket plate connecting bolts, broken bracket shafts, or loosened cylinder fixing nuts. Other causes include vehicle air pressure dropping below 0.8MPa, air leaks at the cylinder intake joints or pipelines, air supply failures leading to no air delivery to the cylinder, stuck butterfly valves preventing normal closure, air leaks in the EVB exhaust pipe cylinder, or wobbling EVB exhaust pipe butterfly valves. Causes of pipeline air leaks: Aging and damage to pipelines, corrosion from microbial chemicals. Causes of EVB exhaust pipe hardware damage: Humid environments, poor ventilation conditions.
Exhaust brake failure can occur due to several reasons. The most common issue is a stuck butterfly valve. When carbon deposits accumulate or cause sticking in the exhaust valve, the butterfly valve can't close properly, resulting in insufficient backpressure and ineffective braking. The last tractor I drove had this exact problem—when we opened it up, the valve was almost completely clogged with black carbon deposits. Another possibility is the exhaust brake cylinder not functioning, which could be due to air hose leaks or cylinder wear. If the air escapes, there's no braking force left. Many modern vehicles use electromagnetic control, and sudden failures can happen if the coil burns out or a fuse blows. In such cases, using a multimeter to check the circuit is necessary to pinpoint the issue accurately.
When driving heavy trucks in mountainous areas, the most dreaded issue is exhaust brake failure. From my experience, pneumatic system problems are the most common. The system won't activate when the air tank pressure drops below 7 kg. In such cases, check if the air compressor belt is loose or if the tank drain valve is frozen and clogged. Rust in the transmission mechanism is another major concern, especially for vehicles frequently making short trips hauling seafood – moisture can cause the rocker arms and connecting rods to rust solid. Some newer truck models' ECUs require engine speed signals; if the speed sensor fails, the system won't function properly. I recommend having mechanics spray rust inhibitor on valve stems and connecting rods during every maintenance – this small precaution can prevent major headaches.
