Impellers

Our range includes JMP impellers.

They are equivalents of Jabsco, Johnson, Volvo, Yanmar and other impellers.

What are the impellers made of?

The most commonly used impellers are neoprene impellers – suitable for use where there are minimal amounts of oil and fuel. Operating temperature: 5–60°C.

On request, we can offer nitrile impellers – used in bilge pumps and in areas heavily contaminated with oil. Operating temperature: 10–82°C.

How often should the impeller be replaced?

It is recommended to check and replace the impeller at least once a year, or more often depending on engine load.

Check whether the raw water pump impeller has any damaged blades. Even the smallest damage will quickly grow larger, and as a result, fragments of the impeller will end up in the system, blocking water flow and leading to engine overheating. In the case of even the smallest cracks, the impeller should be replaced with a new one. This is better than dismantling the entire water circulation system in search of pieces of rubber.

We recommend keeping a spare impeller on board – it is one of the most important components of the engine cooling system!

JMP impellers are supplied complete with grease and gaskets.

How to find the right impeller?

1. If you have the impeller with you:

• measure its height, shaft diameter, and outer diameter,
• check what type of mounting it has – this could be: a pin, a key, a spline (10, 11, 12, or 14 teeth), a hex spline, or a shaft with a single or double flat surface,
• count how many blades it has.

Based on this data, select the impeller from the table at https://silnikimorskie.pl/wirniki-impelery.

2. If you know the original impeller number:

Each impeller's page lists the original impeller numbers – check whether the number and dimensions match.

Most common problems

Hard, cracked tips and blades, missing blades.
Cause:

• dry running, no water in the pump
• temporary suction blockage
• leaking suction line

Solution:

• do not run the pump without fluid for longer than 20 seconds
• install a fluid level sensor/temperature alarm
• check the suction line and filters for blockages and leaks

Pitting in the middle of the blades, visible erosion marks.
Cause:

• cavitation – excessive inlet pressure causes the water to boil inside the pump

Solution:

• reduce pump speed
• increase inlet diameter
• shorten the inlet line, remove unnecessary restrictions

Worn tips and end faces of the impeller blades, shaft wear
Cause:

• abrasive wear from the fluid in the pump
• blocked heat exchanger/radiator
• high outlet pressure

Solution:

• check that nothing is blocking the system
• increase the outlet diameter

The impeller is swollen, the blades appear larger than the hub, the rubber is sticky
Cause:

• this phenomenon most often occurs when the pump is contaminated with oil

Solution:

• flush the impeller after use
• remove the impeller when the engine is not in use

Damaged, bent blades
Cause:

• normal impeller wear
• prolonged storage in the pump

Solution:

• turn the impeller so it rotates in the opposite direction
• remove the impeller when the engine is not in use
• replace the impeller

Blades broken roughly at mid-height, blades missing, reduced flow
Cause:

• normal impeller wear
• high outlet pressure

Solution:

• replace the impeller, check that no remnants of it are left in the pump