Description

The Yanmar 128990-42570 Seawater Pump Impeller Kit is a genuine Yanmar cooling-pump service kit used on select GM and YM series marine diesel engines. It is designed to restore proper seawater circulation through the raw-water cooling system, helping protect the engine from overheating caused by worn, cracked, or damaged impeller vanes. Current Yanmar parts references show this kit replacing earlier impeller number 128990-42200.

Key Features

• Genuine Yanmar seawater pump impeller service kit.
• Used for marine diesel raw-water cooling pump maintenance.
• Kit references include impeller, cover O-ring, cover screws, and lubricant/grease.
• Helps restore cooling-water flow and reduce overheating risk.
• Current technical references list the impeller as 50 mm outer diameter x 22 mm width, with 12 mm inner diameter, 6 blades, neoprene vanes, and brass hub.
• Direct replacement reference for Yanmar 128990-42200.

Engine Compatibility

This kit is commonly listed for select Yanmar marine diesel applications, including:

• 2GM20 — serial numbers beginning with E
• 2GM20F — serial numbers beginning with E
• 3GM30 — serial numbers beginning with E
• 3GM30F — serial numbers beginning with E
• 2YM15
• 3YM20
• 3YM30
• 3YM30AE

Additional references also associate this kit with later GM-YEU and YM-series seawater pump applications, so the engine model and seawater pump assembly should be verified before ordering.

Serial Number Fitment Notice

Impeller fitment should be confirmed using the engine model, serial number, seawater pump part number, or Yanmar parts diagram. GM-series engines in particular may vary by production range, and references commonly specify serial numbers beginning with “E” for 2GM20 / 2GM20F / 3GM30 / 3GM30F applications.

When This Part Needs Replacement

Replace the impeller when raw-water flow is weak, the engine runs hotter than normal, the pump has been run dry, or the old impeller has cracked, stiff, missing, or permanently bent vanes. It is also smart to replace the impeller during seasonal service or whenever the seawater pump cover is already being opened for inspection.

Installation Notes

Install with the seawater pump cover removed. Replace the O-ring and cover screws supplied with the kit, apply the included lubricant/grease to the impeller, and confirm the vanes are folded in the correct direction for pump rotation. After startup, check immediately for leaks and verify strong cooling-water discharge. Never run the seawater pump dry.

Alternate/Superseded Part Numbers

• 128990-42570
• YM-128990-42570
• 128990-42200
• YM-128990-42200
• X08810B

Parts Desk Insight

This is a small service kit, but it protects one of the most important systems on the engine. The safest match is always the engine serial number or seawater pump assembly, especially on GM-series engines where production range matters.

Shipping: Ships same or next day for fast Canada wide shipping.