Yanmar water pumps

Yanmar water pumps

Seawater or freshwater: which Yanmar pump do you need?

On a Yanmar inboard engine, the term "water pump" actually refers to two very different components. They do not have the same function or the same service life. Identifying which pump is at fault is the first step to avoiding ordering mistakes. DAM Marine supports you with genuine and high-quality replacement pumps for the full Yanmar marine range.

Depending on your Yanmar engine architecture, direct or indirect cooling, your needs will not be the same.

  • The seawater pump, or open circuit: it draws water from under the boat to cool the engine or the heat exchanger. This pump is fitted with a neoprene impeller, also known as an impeller wheel. It is the typical wear part: its impeller should be replaced every season or every two seasons.
  • The freshwater pump, or closed circuit / circulation pump: present only on indirectly cooled engines with coolant. It is a centrifugal pump with a metal wheel. It does not require regular maintenance, but will eventually leak because of bearing or mechanical seal wear.
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POMPE AMORCAGE MANUEL...

POMPE AMORCAGE MANUEL GASOIL YANMAR

RÉF. DM_CR_X1522006720 | BOSCH

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How do you identify the correct reference for your Yanmar?

The reference of your pump depends directly on the generation of your engine. Remember to note the exact model and serial number from the manufacturer's plate: with Yanmar, simple production updates can change the reference of a part within the same engine family.

What are the symptoms of a failing Yanmar water pump?

A precise diagnosis avoids unnecessary expense. Here is what your engine is trying to tell you:

  • Weak flow at the exhaust: the seawater circuit is involved. Before blaming the pump, check your seawater filter and the hull strainer. A clogged filter gives exactly the same result.
  • The engine overheats, but water is discharging well: look towards the freshwater pump, a stuck thermostat or a scaled heat exchanger. Pro tip: on an old engine, pieces of a previously torn impeller often block the heat exchanger inlet.
  • Seepage under the pump body: if water flows through the small hole under the pump, the vent hole, the lip seal on the seawater side or the mechanical seal on the freshwater side has failed. Action is needed before water destroys the bearing.
  • Growling noise or play in the shaft: the bearing is at the end of its life. Complete replacement or a major rebuild is required.

Is it better to repair or replace the complete pump?

The repair kit is ideal for routine maintenance, such as replacing the impeller and gaskets, or if the bronze pump body is still in perfect condition.

Complete replacement becomes unavoidable if the pump has significant shaft play, if the body is eaten away by galvanic corrosion, or if the chamber is deeply scored. In an overly worn chamber, even a new impeller will not seal properly and the pump will no longer draw water.

What installation precautions should be followed?

  • Lubricate your new impeller: do not try to prime the seawater circuit dry. Coat the impeller blades generously with the supplied glycerine, or silicone grease, during installation. This prevents the impeller from burning dry during the first seconds of starting.
  • Do not forget the valve: always remember to close your seacock before working, and above all to reopen it before turning the key. Starting with the valve closed destroys a new impeller in less than a minute.
  • Always replace the gaskets: do not reuse the old paper cover gasket, even if it looks clean. A tiny air leak is enough to unprime the pump.
  • Check belt tension: if your pump is belt-driven, insufficient tension will make it slip. Flow will drop even though the pump itself is not faulty.