Mitsubishi R4A51

Transmission general data

The 4-speed automatic transmission R4A51 (V4A51) was used since 1997 for RWD Montero models with engine capacity from 3-liters. In a couple of years, the new 5-speed R5A51 (2000-2006) and AWD V5A51 versions were launched. This family of automatic transmissions competed with RWD AW30-40LE by Aisin.

Technical issues and repair guidelines

Commonly, planned overhaul of these transmissions consists in cleaning of the valve body, repair of the torque converter and ATF change. These measures are assumed to be enough for another 2-3 years of proper operation, if gaskets are intact and the oil pressure in packages conforms to requirements.The reassembly of this transmission usually includes not only the repair kit of gaskets and seals, but also the kit of frictions and the kit of steel discs. A rather long-lived clutch of the torque converter lock-up may be exposed to wearout. In some cases, it may operate until 200 thousand kilometers. The untimely replacement of the friction component results in beatings, damage of the pump seal, and later breakdown of the pump bushing.

Typical problems of R4A51 (V4A51)

Filters are clogged with wear-out products and there are two modifications of filters for transmissions applied in RWD cars. The planetary gear (O.D.) rapidly gets out of order under the condition of extreme and frequent loads close to the torque limit. In the process of reassembly, the valve body is washed and may operate properly till the end of the car lifespan. During the first overhaul, specialists replace some solenoids that operate very intensively, namely EPC solenoid and the solenoid of the clutch lock of the V5A51 torque converter operating in the dirtiest and hottest fluid. Input shaft sensors get out of order because of old age, oil contamination by steel shavings, and overheating It is recommended to replace all frictions and the brake band in case of a long-term operation with burnt fluid.