7S6323 Valve Spring Fits Caterpillar Industrial Construction Engines D379One New Aftermarket Replacement Valve Spring Fits Caterpillar (Fits CAT) D Series Industrial and Marine Engines This aftermarket replacement valve spring Fits Caterpillar (Fits CAT) D Series diesel engines and serves both intake and exhaust positions in the cylinder head valve train. The valve spring maintains tension to keep valves firmly seated against their seats until the camshaft opens them, ensuring proper combustion chamber sealing and engine