Why does the Subaru 5AT transmission fail?
2 Answers
There are three main reasons for Subaru 5AT transmission failures. Aging or damaged oil seals: Transmission oil leakage issues are primarily found in half-shaft leaks, front oil seal leaks, and front differential leaks. Chain and pressure cylinder wear: CVT transmissions are prone to chain and pressure cylinder failures after the vehicle has traveled a certain mileage. Subaru Forester transmissions may exhibit abnormal noises, slipping, shaking, slow acceleration, and even severe consequences like inability to move. Clutch failure: Clutch wear occurs under normal operating conditions. However, when the transmission experiences high internal temperatures, the clutch plates inside the clutch can overheat and burn out, leading to issues such as slipping, shaking, gear disengagement, and failure to accelerate when pressing the accelerator.
I've driven several Subarus, and their 5AT transmission failures are indeed a headache. The most common issues occur with the valve body and solenoids - these small components controlling hydraulic pressure are particularly prone to sticking or wearing out. Especially after 70,000-80,000 kilometers, you can always feel jerking during gear shifts, and sometimes sudden freewheeling occurs. The torque converter's lock-up clutch is another trouble spot, with older vehicles frequently experiencing reduced power transmission efficiency. Electronic control module failures are even more troublesome, as sensor false alarms directly cause shifting logic confusion. The worst case I've seen was burnt clutch plates, mostly caused by owners not changing transmission fluid for five or six years. I recommend fluid testing every 40,000 kilometers, and immediately checking the hydraulic system if shifting becomes rough.
