Johnson Pump 09-704BT-1 Replacement Impeller (MC97)

The Johnson Pump 09-704BT-1 Impeller (MC97)  is a high-performance replacement impeller engineered for use in engine cooling and general-purpose water transfer pumps. Made from Johnson’s proprietary MC97 rubber compound, this impeller is specifically designed to meet the strict demands of modern marine engines, offering better swell resistance and a longer service life than standard neoprene.

The MC97 Advantage

MC97 is a high-grade EPDM-based compound developed by Johnson Pump to combat the effects of additives in modern oils and cooling fluids. This material provides excellent "memory" (the ability of the blades to return to their original shape), which ensures consistent self-priming and maximum flow rates even after the pump has been sitting idle for long periods.

Key Features:

• Optimal Engine Cooling: Designed to provide the precise flow and pressure required to keep marine engines running at stable temperatures.

• High-Quality MC97 Material: Offers superior resistance to ozone, heat, and chemical wear compared to traditional rubber impellers.

• Reliable Self-Priming: The flexible blades create a vacuum that allows the pump to pull water instantly upon startup.

• Precision Fit: Manufactured to exacting tolerances to ensure a perfect seal within the pump housing, preventing internal bypass and efficiency loss.

• Broad Compatibility: Fits a wide variety of Johnson F9 series pumps and is a common replacement for many Volvo Penta, Indmar, and Kohler marine engines.

Technical Specifications:

• Part Number: 09-704BT-1

• Material: MC97 (EPDM-based)

• Outer Diameter: 3.74" (95 mm)

• Inner Diameter (Shaft): Spline Drive (typically fits 1" / 25mm shafts)

• Width: 2.48" (63 mm)

• Drive Type: Splined

• Number of Blades: 10

Why Choose the 09-704BT-1?

The Johnson Pump 09-704BT-1 Impeller (MC97)  is the "go-to" impeller for heavy-duty marine applications. Because it is made of MC97, it is highly recommended for engines that run in warmer waters or for commercial operators who require the most durable materials available. Replacing your impeller annually (or every 100 hours) is the cheapest insurance you can buy against catastrophic engine overheating.

Maintenance Tip:

When installing your new impeller, always use a silicone-based lubricant (often included in the kit) on the blades and the inside of the pump housing. This protects the blades from friction damage during the "dry" seconds of the very first startup before water reaches the pump.