JPR-YM04JHB Aftermarket Yanmar 3JH4E/3JH5E/4JH5E Seawater Pump 129271-42502 | Sawley's Select Marine Parts

🔧 Product Description

Aftermarket JMP Yanmar later JH-series seawater pump with drive gear - Replacement Part Number: JPR-YM04JHB

A later-type seawater pump for Yanmar 3JH4E, 3JH5E, 4JH4E, 4JH4AE and 4JH5E engines plus the 4JH common-rail family. It replaces Yanmar 129271-42502 and earlier 129271-42500/-42501 and is supplied with the drive gear and mounting gasket.

⚙️ Key Features

• Heavy-duty marine bronze pump body

• Flexible-impeller positive-displacement design

• Marine-grade non-magnetic stainless-steel shaft

• Replaceable mechanical seal, bearings, cam and wear components

• Designed to match the listed OEM mounting, rotation and connection layout

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• Yanmar 129271-42502 → Supersedes 129271-42501 and 129271-42500

• Johnson 10-13328-01 / 10-13328-03 are original pump cross-references

OEM / Related Numbers:

• JPR-YM04JHB

• Yanmar 129271-42502

• Yanmar 129271-42501

• Yanmar 129271-42500

• Johnson 10-13328-01

• Johnson 10-13328-03

• Mounting gasket: Yanmar 129150-01881

• Major service kit: JMP JSK0130

• Minor service kit: JMP JSM0130

Aftermarket / Verified Equivalents:

• JMP Marine: JPR-YM04JHB

Included Components:

• Complete seawater pump - Part Number: JPR-YM04JHB

• Drive gear - supplied fitted

• Mounting gasket - Part Number: Yanmar 129150-01881

🚤 Compatibility

Commonly used on:

• Flexible-impeller raw-water cooling systems

Typically suits:

• Engine models:

• Yanmar 3JH4E and 3JH5E

• Yanmar 4JH4E and 4JH4AE

• Yanmar 4JH5E

• Yanmar 4JH45, 4JH57, 4JH80 and 4JH110

• HP Range: Engine-rating specific; approximately 39HP-110HP

• Engine Type: Yanmar later JH-series three- or four-cylinder marine diesel

• Year Range: Model-specific; confirm OEM pump 129271-42502 family

• Drive Gear: Included

• Mounting Gasket: Yanmar 129150-01881 included

🔌 Function

The seawater pump draws raw water through the intake and circulates it through the engine, heat exchanger, oil cooler, aftercooler and wet-exhaust circuit as applicable. Its flexible impeller must maintain adequate flow from idle through full load while the shaft, bearings and mechanical seal keep the drive and water sections correctly supported and separated.

Common signs of failure:

• Engine temperature rises under load or at higher RPM

• Reduced or intermittent water discharge from the exhaust

• Missing, cracked, swollen or permanently set impeller vanes

• Seawater leakage or salt tracks from the shaft seal or weep area

• Bearing noise, pulley or gear wobble, or excessive shaft movement

• Scored cover plate, worn cam or damaged pump housing reduces suction

• Internal corrosion, air leakage or blocked inlet passages cause loss of prime

📦 Condition

• Brand new aftermarket replacement part

• New and unused

• Supplied in manufacturer or equivalent protective packaging