Yanmar Pleasure Boat Marine Engine Help

2QM15 YS photo 6LP

RAW water pump servicing

The raw water pump shown below is for a 1GM but it gives an idea of what most pump types look like on the inside. If your model isnt shown above, 'EMAIL for HELP' and if I can find it I'll post it here.

Check the pump for serviceablilty, starting from the left side of the drawing, as follows:

• Item 14, the COVER PLATE, must be flat on the side nearest the impeller. If it isnt you need to re-surface it, turn it over or buy a new one. The plate gets grooves worn in it and the water bypasses the impeller.


• Item 15, there must be only one PAPER GASKET, lightly smeared with grease. The gasket contact surface on the pump must be flat with no bits of old gasket, paint or screwdriver score marks across the sealing face.


• Item 3, IMPELLER, must have no cracks on the blades and no grooves at the blade tips or sides. The centre bush must not be able to turn by itself.


• Item 5, CAM. Must not be badly grooved and should also be replaced if the ends are razor sharp.


• Item 24-1, PUMP BODY. Inside, where the impeller runs, must not be badly grooved. Unfortunately , if it is, the complete pump will have to be replaced.


• Item 31, O-RING to stop the oil leaking out of the engine and dripping into the bilge.


• Item 9, LIP SEAL to keep the water out of the engine. The lip part must face toward the water (impeller). The spring inside must be stainless steel or an 'O'ring.


• Item 8, LIP SEAL to keep the engine oil out of the water pump. The lip part must face toward the oil.


• Item 7, BALL BEARING assemblies. Must spin freely without any 'notchyness'.


• Item 4, PUMP SHAFT. This must not be worn where the lip seals run as they will leak. The left hand end must be free of damage and fit neatly into the bush in the impeller. The right hand end is a driving tang and must not be worn to a point where it may slip around inside the driving fork in the engine. Check the driving fork in the engine is not worn enough to make the tang rotate inside it.


• Item 12, a retaining CIRCLIP that stops the shaft moving along it's axis.


• Item 13, a retaining CIRCLIP that holds the assembly inside the righthand pump body.

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