5.9 12v Cummins Valve Stem Seal 3957912 SKU: cum3957912

5.9 12v Cummins Valve Stem Seal | Cummins 3957912 (Top Hat Style)
Stop oil consumption and eliminate blue smoke on startup with the genuine Cummins 3957912 Valve Stem Seal. This is the popular top-hat style seal designed specifically for the 5.9L 12-valve Cummins (6BT). It installs directly over the existing valve guide bosses in the cylinder head, no machining required.
These seals control oil flow down the valve stems to prevent excess oil from entering the combustion chamber. Worn or hardened original seals are a common source of blue smoke (especially on cold starts and deceleration) and increased oil use on high-mileage 12-valve engines. Replacing them restores proper sealing and helps keep your engine running clean and efficiently.
Genuine Cummins part #3957912
Top-hat design for easy drop-in installation (no head machining needed)
Controls oil consumption and reduces exhaust smoke
Durable OEM-style construction for long service life
Direct replacement for factory valve stem seals
Ideal during valve jobs, head gasket service, or top-end refreshes
Most 12v owners replace all 12 seals at the same time when the head is off. Pair this with new valve spr[...]