Tools Needed to Service Raw Water Impeller Kits

When it comes to maintaining your Perkins, Volvo Penta and Yanmar marine engine, one of the most important service tasks is inspecting and replacing the raw water pump impeller. The impeller plays a crucial role in circulating seawater through your engine’s cooling system. Over time, the rubber blades wear down, harden, or even break — leading to overheating and potential engine damage.

Servicing your raw water impeller regularly ensures reliable cooling performance To carry out this job safely and efficiently, you’ll need the right tools. Below are tips on the essential tools and materials required.

Essential Tools for repairing a Raw Water pump.

1. Spanners or Screwdrivers

Usually, the pump cover plate is secured by either four or six 'slotted retaining screws or  bolts. 

• Use the correct size spanner or socket to prevent rounding the bolt heads.
• Flat-head or Phillips screwdrivers will help remove covers and hose clamps efficiently.
• To remove the pump from the engine spanners are required. 

Tip: Fasteners can seize over time, so apply gentle pressure and a penetrating lubricant if they resist turning.

2. Rubber Mallet

A rubber mallet is ideal for gently tapping the impeller housing or shaft without causing damage.

• Avoid using a metal hammer, which can distort or crack the pump housing.
• A few light taps will help loosen a stuck impeller or stubborn gasket seal.

3. Vice

A bench vice provides a stable platform to hold the impeller housing during disassembly or reassembly.

• Secure the housing carefully with soft jaws or rags to avoid scratching the surface.
• It’s particularly useful when removing or pressing in the impeller shaft or seals.

4. Silicone Grease

Before fitting a new impeller, coat it lightly with marine-grade silicone grease.

• This lubricates the impeller for the initial dry start, preventing rubber burn.
• It also helps create a watertight seal and makes future removal easier.

Avoid petroleum-based lubricants, as these can degrade rubber over time.

5. RTV Silicone Sealant

Silicone sealant is ideal for resealing the pump  to the housing.

• Apply a thin, even bead where the gasket meets the metal surface.
• It prevents water leaks and ensures a long-lasting, tight seal..

6. Circlip Pliers

If your impeller pump includes circlips securing the shaft or bearings, you’ll need a good pair of internal/external circlip pliers.

• They make removal and installation much easier and prevent damage to precision components.
• Always check the circlip grooves for wear or corrosion before refitting.

7. Hydraulic Press (Ideal)

For a removal of the shaft or bearing, a hydraulic press is extremely useful.

• It ensures even pressure when fitting or removing impeller shafts, bearings, or seals.
• Using a press helps avoid misalignment and damage to the components. 

If you don’t have access to one, a vice can often substitute — just apply pressure slowly and evenly.

Additional Tips for Servicing Your Raw Water Pump

• Inspect the old impeller carefully — if blades are missing, check the cooling circuit for debris.
• Replace the cover plate gasket each time to ensure a watertight seal.
• Flush the system with clean water before refitting the pump.
• Keep a spare impeller kit onboard — it’s one of the most common emergency repairs for marine engines.

🧩 Recommended Impeller Kits & Parts

At Parts4Engines, we stock genuine and high-quality aftermarket raw water impeller kits for Perkins, Volvo Penta and Yanmar marine engine.

Each kit includes the impeller, gaskets, seals, and O-rings required for a complete service.

👉 Shop Perkins, Volvo Penta and Yanmar impeller Kits