A-31431991-AI Valve, ExhaustOne New Aftermarket Replacement Exhaust Valve for Perkins A3. 152 AD3. 152 AD4. 203 Engines This aftermarket replacement exhaust valve fits Perkins A3. 152, AD3. 152, and AD4. 203 diesel engines, which are commonly found in Fits Massey Ferguson tractors, industrial equipment, and construction machinery. The exhaust valve seats in the cylinder head and controls the release of combustion gases from the engine, playing a critical role in maintaining