JMP Marine 7608K Impeller Kit – Sherwood 27000K Replacement

JMP Marine 7608K Flexible Impeller Kit — 12-Blade Spline Drive Impeller with O-Ring and Lubricant

The JMP Marine 7608K impeller kit is the complete service package for raw water and seawater cooling pumps built on the Sherwood 27000 platform. Inside the box you get the flexible impeller itself, the matching ORG0030 O-ring, and a sachet of impeller lubricant, so a pump rebuild does not stall halfway because a seal was left out. The impeller measures 82.4mm in diameter with a 73.4mm width and a 20mm bore, carries twelve flexible blades, and uses an 11-tooth spline drive insert. It is a direct replacement for Sherwood 27000 and 27000K, and for the Cummins 3974456 part number.

What separates this kit from a generic replacement is the compound. JMP uses a proprietary neoprene-based formula developed for continuous contact with untreated water, with wax carried through the body of the material rather than applied only to the surface. That matters because a flexible impeller lives or dies on how well its blades resist taking a set and how gracefully they handle the brief dry starts that happen every time an engine is fired up. Brass inserts are moulded in place of stainless, which keeps galvanic behaviour predictable in the wet side of a cooling circuit and makes the impeller easier to draw out at the next service.

It is worth saying plainly that this is not strictly a boat part. The same Sherwood-pattern pumps show up on stationary and standby generator sets, on industrial and agricultural diesel installations, on skid-mounted engines, and on plenty of freshwater and closed-loop cooling jobs that never see salt. Anywhere a 27000-series pump is turning, the 7608K fits, and the neoprene compound is equally at home in fresh water, brackish water, or seawater. Most operators treat it as an annual replacement item and keep a spare on the shelf, because a shredded impeller almost never fails at a convenient moment.

Key Features

• Complete service kit: flexible impeller, ORG0030 O-ring, and impeller lubricant included
• Proprietary neoprene compound engineered for raw water, brackish water, and seawater service
• Wax branding carried through the full thickness of the material, not just the surface, for longer blade life
• Brass insert construction rather than stainless steel for predictable behaviour in wet-side cooling circuits
• Twelve flexible blades for smooth, consistent flow and reduced pulsation
• 11-tooth spline drive insert for positive shaft engagement
• Direct drop-in replacement requiring no pump modification
• Suitable for both fresh water and salt water systems

Applications

• Sherwood 27000 and 27000K raw water pumps
• Cummins engine cooling pumps using part number 3974456
• JMP JPR-S7608 seawater pump (Cummins QSB5.9, QSB6.9)
• JMP JPR-S7616 seawater pump (Cummins replacement)
• JMP JPR-S7619 seawater pump (John Deere 6067AFM, 6081AFM01 and related)
• JMP JPR-S7622 seawater pump (Cummins replacement)
• JMP JPR-S7627 seawater pump (Cummins 6CT, 6CTA8.3M)
• JMP JPR-S7630 seawater pump (Cummins 6CT, 6BTA5.9M variants)
• JMP JPR-S7632 seawater pump (Caterpillar 3116, 3126, C7, C9)
• JMP JPR-S7633 seawater pump (John Deere replacement)
• Marine propulsion and auxiliary engine cooling systems
• Stationary and standby generator set cooling
• Industrial, agricultural, and skid-mounted diesel engine cooling

Specifications

• Part Number: 7608K (also supplied as 7608-01K)
• Kit Contents: 1x impeller, 1x O-ring (ORG0030), 1x impeller lubricant
• Impeller Diameter: 82.4mm
• Impeller Width: 73.4mm
• Shaft Bore Diameter: 20mm
• Number of Blades: 12
• Insert Type: Spline Drive, 11 tooth
• Insert Material: Brass
• Impeller Material: Neoprene compound with through-material wax branding
• Water Compatibility: Fresh water, brackish water, seawater
• Replaces: Sherwood 27000, Sherwood 27000K, Cummins 3974456
• Recommended Service Interval: Inspect regularly, replace at least annually

FAQs

Q: Is the 7608K the same as the 7608-01K?

A: Yes, they are the same service kit. JMP added the -01 suffix during a running revision, and both part numbers ship the same impeller, O-ring, and lubricant with identical dimensions and fitment.

Q: Do I need to remove the whole pump to change this impeller?

A: In most installations you do not. The impeller is accessed by removing the pump cover plate, which lets you extract and replace the impeller in place. Access clearance varies by engine bay, so on tight installations some technicians prefer to pull the pump.

Q: What causes a flexible impeller to fail early?

A: The two usual culprits are running dry and a restricted inlet. Even a few seconds without water generates enough heat and friction to glaze or tear the blades, and a partially blocked strainer or a collapsing suction hose starves the pump the same way. A sudden drop in cooling water flow is worth investigating before the next start.