With many of the Hydramatic transmissions taken in (see pictures), the parts are extensively varnished and difficult to clean without special cleaning equipment. Some transmissions have sat in a barn, field or salvage yard for decades and these can look to be in very poor condition. Some owners think that these units cannot be brought back to life - but I disagree!
Hot Bath Thermal-Cleaning, the cleaning process I use on all transmissions, is different than for cleaning an engine block. With an engine, the block and heads are heated in a flame-oven to burn off debris. With a transmission, which contains aluminum, brass, stainless, and other soft metals, the cleaning process should NEVER be harmful to the components. Classic Hydramatic cleans parts in a special high-temperature high-PH detergent water jet bath that deep cleans the parts but does not harm soft metals. From the washer the parts are hand rinsed and inspected to ensure that your Hydramatic parts are fully clean. Case parts are then painted, sensitive components such as valve bodies and governors are 100% disassembled and hand cleaned and lubricated, and a final inspection is completed on all parts.