Yanmar 129670-42610 Seawater Pump Impeller Kit (Genuine OEM)

Description

The Yanmar 129670-42610 is the genuine OEM seawater pump impeller kit for Yanmar 3JH and 4JH series marine diesel engines. It is a complete kit rather than a bare impeller: you get the twelve blade neoprene impeller, the pump cover plate O-ring, and the cover plate screws, which are the parts you actually need to do the job properly in one go.

The part that strands people

The raw water impeller is the most common cause of an overheating alarm on a marine diesel, and it is a wear part by design. The blades are flexible neoprene running against a cam inside the pump body, and they take a set, harden, crack, and eventually shed blades. When blades break off they travel downstream into the heat exchanger, so a failed impeller is rarely just an impeller job. Replace it on schedule and keep the old one as a get-you-home spare rather than running it to destruction.

Never run it dry

A neoprene impeller is cooled and lubricated by the water it pumps. Running the engine with the seacock shut, even briefly, will damage it. If you have had the raw water system apart, or the boat has been hauled, check the seacock is open before you start.

Removal

This impeller is threaded for use with the Yanmar impeller puller 129671-92110. Trying to lever a tight impeller out with screwdrivers is how pump housings and cover plate faces get damaged, so use the correct puller if the impeller does not come out by hand. Fit the new cover plate O-ring supplied in the kit rather than reusing the old one, and count the blades on the impeller you removed. If any are missing, find them before you close the system up.

Check your fitment

The engine models listed in the product specifications are a guide only. Always confirm against the parts catalogue for your engine’s model and serial number before ordering. If you are unsure, send us your engine plate details and we will check it for you.

Genuine Yanmar parts

We stock genuine Yanmar OEM parts, not pattern copies. If you need help identifying the right part for your engine, or want to book a service, get in touch.