15000K Replacement Impeller Kit | Johnson Pump JP-09-707B-1

Johnson Pump Impeller Kit | JP-09-707B-1 | 15000K | MC97 | Cummins 4B 6B QSD | MerCruiser 7.3L

The Johnson Pump #JP-09-707B-1 is the 15000K replacement impeller kit for Cummins marine diesel and MerCruiser diesel raw water cooling pump applications. The kit includes the impeller, Johnson Pump original impeller lubricant, O-ring, gasket, and four cover screws — everything required for a complete impeller service without a separate parts order. The impeller is manufactured from MC97 elastomer, Johnson Pump's proprietary rubber compound engineered for marine raw water applications. MC97 provides superior resistance to fatigue failure compared to standard neoprene impellers and supports self-priming in low-water or air-entrained conditions. Replaces Sherwood 15000K and Jabsco 18327-0001-P.

Part Details:

• Part Number: JP-09-707B-1 (Johnson Pump)
• Manufacturer: Johnson Pump
• Type: Replacement Impeller Kit — Raw Water Cooling Pump
• Impeller Designation: 15000K
• Drive Type: Keyed shaft
• Blades: 12
• Outer Diameter: 65.2 mm / 2.56 in
• Width: 51.4 mm / 2.02 in
• Material: MC97 elastomer (Johnson Pump proprietary compound)
• Kit Includes: Impeller, Johnson Pump lubricant, O-ring, gasket, 4 cover screws
• Replaces Sherwood: 15000K
• Replaces Jabsco: 18327-0001-P
• Condition: New

Compatible Engine Applications:

• Cummins 4B marine diesel
• Cummins 6B marine diesel
• Cummins 4.2L QSD marine diesel
• MerCruiser 7.3L Diesel
• MerCruiser 4.2L QSD
• Malibu AXIS M6Di

Additional Information

MC97 Elastomer — Why It Matters:

Johnson Pump's MC97 compound is engineered specifically for the demanding conditions of marine raw water impeller service — continuous submersion, temperature cycling from cold starts to full operating temperature, salt and brackish water exposure, and occasional dry-run events during priming. Key properties that differentiate MC97 from standard neoprene impellers:

• Fatigue resistance — MC97 vanes flex millions of times over the impeller's service life; the compound is formulated to resist the micro-cracking that causes premature vane failure on standard rubber impellers, with Johnson Pump reporting service life up to 4x longer in some applications
• Self-priming capability — MC97's elasticity and recovery allow the impeller to prime the pump even with air in the system, reducing the risk of a no-flow condition on startup
• Chemical resistance — resistant to saltwater, brackish water, and the combustion byproducts that can contaminate raw water circuits on diesel engines

Impeller Kit vs. Impeller Only — Why the Kit Is the Right Choice:

The JP-09-707B-1 kit includes the O-ring, gasket, and cover screws in addition to the impeller. These sealing components should be replaced every time the pump cover is removed — reusing the old O-ring and gasket on a diesel engine cooling pump risks a coolant leak that can go undetected until the engine overheats. The included cover screws account for the corrosion and galling that commonly affects stainless hardware in a raw water environment. Ordering the kit instead of the impeller alone eliminates a separate hardware order and ensures the pump is reassembled with fresh sealing components.

Frequently Asked Questions

1. How do I confirm this impeller kit fits my engine?
Cross-reference JP-09-707B-1 (or Sherwood 15000K / Jabsco 18327-0001-P) against your engine's parts diagram. For Cummins marine diesels, use your engine model and serial number to confirm the correct raw water pump impeller part number. For MerCruiser diesel applications, use your engine's model and serial number in the MerCruiser parts catalog. Contact us at MacombMarineParts.com with your engine model and serial number if you need fitment confirmation before ordering.

2. What is the service interval for this impeller on a Cummins or MerCruiser diesel?
Cummins and MerCruiser diesel raw water impeller replacement intervals vary by engine model and operating environment. As a general guideline, annual or 200-hour inspection is standard for most diesel inboard applications, with replacement at the first sign of vane wear, cracking, or reduced flow — or after any dry-run event regardless of hours. Refer to your specific engine's service manual for the OEM-recommended interval. MC97's extended service life means some applications can go longer between replacements, but visual inspection at each season is still recommended.

3. What happens if broken impeller vanes are not recovered?
Broken vane fragments travel downstream through the raw water circuit and lodge in the heat exchanger, thermostat housing, or exhaust elbow water passage — restricting flow and causing the same overheating that prompted the impeller replacement. Always inspect the downstream cooling circuit and flush the system when replacing an impeller with missing or broken vanes. This is particularly critical on diesel inboard applications where heat exchanger access may require significant disassembly.

4. Can I use this impeller in a Sherwood or Jabsco pump housing?
Yes — the JP-09-707B-1 replaces Sherwood 15000K and Jabsco 18327-0001-P, confirming dimensional compatibility with those pump housings. The impeller dimensions (65.2 mm OD × 51.4 mm wide, keyed shaft, 12-blade) are interchangeable with the Sherwood and Jabsco equivalents in compatible pump housings.