The MAZDA 323 diesel engine is a transverse in-line four-cylinder engine. The cylinder block is made of gray cast iron, the cylinder head is made of light metal. The valves are driven via rocker arms from an overhead camshaft. Valve clearance is adjusted by adjusting screws and must be checked and adjusted as part of maintenance, when noise occurs in the timing mechanism or after engine repair. The timing belt that drives the camshaft also drives the high pressure fuel pump (injection pump).