Change impeller on Cat 51 STB

Close engine’s raw-water seacock.

Remove the seawater-pump cover.

Remove the old impeller and account for every blade.

If any blades are missing, locate and remove them from the cooling system before proceeding.

Inspect and clean the pump housing and cover plate.

Lubricate the new impeller with glycerin or soapy water.

Install the new impeller with a new gasket/O-ring.

Reinstall and evenly tighten the cover.

Open the raw-water seacock.

Start the engine and immediately verify strong cooling-water discharge from the exhaust.

Photograph both removed impellers and completed installations.