Yanmar 121575-42150 Cover for GM and GMF
The Yanmar 121575-42150 is the genuine cover for the bronze sea water pump fitted to GM and GMF Series engines. It closes one end of the pump and, just as importantly, forms the flat face the impeller vanes seal against on that side of the pumping chamber.
Covers go out of shape. Repeated overtightening bows the plate between its screws, and once it is bowed it no longer bears evenly on its seal or presents a flat face to the impeller. The symptom is a pump that draws air instead of water - weak exhaust flow, slow priming, and an engine that runs warm while the strainer and the seacock are demonstrably clear.
Key Features
- Genuine Yanmar replacement cover
- Fits the bronze sea water pump fitted to GM and GMF Series engines
- One per pump
- Restores a flat sealing face for the impeller
- Replaces a distorted, pitted or corroded cover
- Renew the cover seal at the same time
Applications
- the bronze sea water pump fitted to GM and GMF Series engines
- Raw water pump rebuilds and impeller changes
- Curing air being drawn in at the cover joint
- Replacing a cover bowed by overtightening
- Repairing corrosion damage on a pump that has seen years of salt water
- Spring commissioning and layup service
Specifications
- Brand: Yanmar
- Manufacturer: Yanmar Marine
- Manufacturer Part Number: 121575-42150
- Part Type: Cover
- Fits: The bronze sea water pump fitted to GM and GMF Series engines
- Quantity Used: One per pump
- Condition: New
Frequently Asked Questions
Q: How do I tell if the cover is distorted?
Lay it on something known to be flat and look for daylight under the edges, particularly between the screw holes. A bowed cover will not seal and will not present a flat face to the impeller.
Q: My pump draws air rather than water. Could the cover be the cause?
It is one of the first places to look, along with the cover seal and the intake hose. Air drawn in at the cover joint gives a weak exhaust stream with a perfectly clear strainer.
Q: How tight should the cover screws be?
Snug and even, in a cross pattern. Overtightening is what bows the cover in the first place, and a bowed cover leaks however hard it is done up.
Q: Should the seal be replaced with the cover?
Yes. It has been disturbed and it takes a set in the joint, and a new cover on an old seal is a leak waiting to happen.
Not sure this is the right part? Send us a Picture of the Pump Plate on your pump and the CLR Marine team will confirm the correct cover.
CLRMarine
