CUMMINS-4BT-6BT-VALVE-OIL-SEAL

3921640 is the valve stem oil seal for Cummins 4BT and 6BT engines, fitted over each valve guide to meter oil to the valve stem without letting excess past into the cylinder. These seals are rubber compounds that harden and crack with heat cycling well before the metal components around them wear out, and replacing them as a full set during any top-end work is standard practice rather than waiting for individual seals to fail. Orange.net.za delivers fast across South Africa.