Indmar Marine Raw Water Pump Impeller | Part #685007

The single most important annual service part for your Indmar engine — this genuine Indmar raw water pump impeller should be replaced every season without exception. A healthy impeller means a healthy cooling system. A failed impeller means no cooling water flow and a catastrophically overheated engine in minutes. This small rubber component is without question the cheapest insurance policy you can buy for your Indmar marine engine.

Compatible with: Indmar marine engines with Johnson raw water pumps fitted to Malibu, Moomba, Supra, and Tige boats. Contact us to verify fitment for your specific model year before ordering.

What does the impeller do?
The impeller is the rotating rubber component inside your Johnson raw water pump that draws water from outside the boat and pushes it through the cooling circuit. Every drop of cooling water that keeps your engine alive passes through this part. Without a functioning impeller your engine has no cooling whatsoever — overheating occurs rapidly and the damage can be catastrophic and irreversible.

Why does it need annual replacement?
The impeller is made from rubber and works under constant flexing, heat, and friction inside the pump housing. Over time the rubber:

• Hardens and loses flexibility — reducing pumping efficiency even before visible failure
• Develops cracks at the blade roots from constant flexing under load
• Sheds blades that travel through the cooling system and block passages
• Deteriorates from sitting dry over winter — rubber flat-spots and loses its pumping memory

This is why annual replacement is non-negotiable — even if the impeller looks intact, hardened rubber dramatically reduces cooling water flow long before complete failure occurs.

Warning — the danger of impeller fragments:
When an impeller fails it rarely fails all at once. It sheds rubber blades that travel through your cooling system and lodge in:

• The thermostat housing
• Heat exchanger passages
• Exhaust cooling galleries
• Coolant hose bends and restrictions

These fragments can block cooling passages and cause continued overheating even after a new impeller is fitted. Whenever replacing a failed impeller always flush and inspect the entire cooling system for fragments before returning the engine to service.

Signs your impeller needs immediate attention:

• Engine running hotter than normal or overheating
• Reduced or no water flow from the exhaust outlet at idle
• Coolant temperature spiking under load on the water
• Impeller has not been replaced this season
• Rubber fragments visible anywhere in the cooling system
• Engine has been run dry — even briefly
• Boat has sat unused over an extended winter storage period

How often should you replace it?
Every season — no exceptions. The cost of a genuine Indmar impeller is negligible compared to the cost of an overheated engine. Even if your engine ran perfectly all summer, replace the impeller at your end of season or pre-season service every single year.

Installation tips for maximum impeller life:

• Apply a thin coat of waterproof grease or dish soap to the impeller blades before fitting — this lubricates the critical dry startup period before water flow is established
• Always replace the pump gasket at the same time — part #685008
• Never run the engine dry — even for a few seconds — as this destroys the impeller almost instantly
• Ensure correct impeller blade direction on installation — blades must curve in the correct rotation direction

Pro tip: Always carry a spare impeller and gasket on board — along with the basic tools to fit them. An impeller failure is one of the most common causes of on-water breakdowns and one of the easiest to fix if you have the parts with you. A spare impeller kit on board could save your engine, your day, and an expensive tow home.

The complete annual impeller service — order together:

• 685007 – Raw Water Pump Impeller (this part)
• 685008 – Impeller Pump Gasket Johnson
• 685001 – Raw Water Pump Full Barb (if pump body replacement required)

Pairs perfectly with:

• 685008 – Impeller Pump Gasket Johnson
• 685001 – Raw Water Pump Full Barb
• 845040 – Hose J-Formed with Spring
• 866081 – Thermostat Housing Aluminium Full F/W
• 986034 – Thermostat 160° Drilled LT1 & 5.7L F/W
• 985006 – Thermostat Housing Gasket

Features:

• Genuine Indmar OEM part
• Correct rubber compound and blade geometry for Johnson raw water pump
• Precision moulded for maximum cooling water flow
• Compatible with Indmar Johnson raw water pump — 685001
• Annual replacement recommended — regardless of visible condition
• Direct replacement — no modifications needed

Part Number: 685007
In stock and shipped fast from Australia 🇦🇺