Clutch Slave Cylinder 8-97148625-1 8971486251 For ISUZU NPR66 NKR66 NPS66 ELF350 4HF1 4.3L — 1" Bore, RHD, Direct Fit

The Clutch Slave Cylinder with OEM numbers 8-97148625-1 / 8971486251 is a verified direct-fit hydraulic component for ISUZU NPR66, NKR66, and NPS66 trucks equipped with the 4HF1 (4.3L) diesel engine, as well as several other ISUZU N-Series models from the 1991–2005 production window. This cylinder converts the hydraulic pressure generated by the clutch master cylinder into mechanical force that disengages the clutch pressure plate, enabling gear changes.

The part is cataloged by ISUZU under the description "SILINDER; SLAVE, CLU" (Cylinder; Slave, Clutch) and is a known wear item on manual-transmission N-Series trucks. It is available in both OEM (ISUZU Genuine) and aftermarket quality tiers, with the aftermarket sector including established brands such as BGF, SB, and Seiken. The cylinder is positioned for Right-Hand Drive (RHD) applications and uses a 1-inch (25.4 mm) bore diameter.

• Bore Diameter Verified: 1 inch (25.4 mm) — confirmed by SB (Brettstruck) technical data for the CO24010 reference, which cross-references the NPR66 4HF1 application.
• Weight Verified: 0.668 kg net weight — confirmed across multiple supplier listings for 8-97148625-1 / 8971486251.
• Position / Drive Verified: Right-Hand Drive (RHD) — confirmed by SB technical data ("Position: RHD") for the NPR66 application.
• HS Code Verified: 870893000 — confirmed by supplier export documentation for this clutch slave cylinder.
• OEM Reference Cross-Verified: Primary OEM 8-97148625-1 / 8971486251; additional references 97148625 and 8-914866-3-1 appear in supplier catalogs.
• Aftermarket Cross-Reference Verified: CO24010 (SB), PJL904 (BGF), 15651.008, and 8970328471 / 8970328470 are listed as interchangeable/cross-reference numbers for the same N-Series application family.
• Fitment Coverage Verified: Confirmed for NPR66 4HF1 (1991–2005), NKR66 4HF1 (1994–2005), NPS66 4HF1 (1994–1996), plus NPR70 4HE1, NPR71 4HG1, and NPS71 4HG1 applications.

• Clutch pedal feels spongy or sinks to the floor: The most common symptom. A failed slave cylinder seal allows hydraulic pressure to escape internally or externally, producing a soft pedal that may not disengage the clutch.
• Clutch fluid leak at the slave cylinder: Visible wetness around the cylinder body, push rod, or bleeder screw. Brake/clutch fluid is corrosive and will damage paint and surrounding components.
• Difficulty engaging or disengaging gears: If the slave cylinder cannot generate sufficient travel, the clutch may drag, making gear selection difficult — especially when cold or at a standstill.
• Clutch pedal returns slowly or stays down: A seized or bypassing slave cylinder can prevent the pedal from returning to its rest position.
• Fluid level dropping in the clutch reservoir without an obvious external leak: Internal seal failure can allow fluid to bypass without pooling externally, leading to a gradual loss of pedal feel.

Confirmed Fitment Sources: Brettstruck (Australian ISUZU parts specialist) explicitly lists the CO24010 slave cylinder for NKR66 4HF1 (1994–2005), NKR69 4JG2 (1994–2005), NPR66 4HF1 (1991–2005), NPR70 4HE1 (1999–2005), NPR71 4HG1 (1996–2005), NPS66 4HF1 (1994–1996), and NPS71 4HG1 (1996–2005), with 1" bore and RHD configuration. BGF brake confirms the same 8-97148-625-1 reference for ELF (NKR7#, NKS7#, NHR6#, NKR6#, NPR#6) with 4HE1 / 4HF1 / 4HG1 / 6HK1 engines, 4.3L / 4.6L / 4.8L diesel, manual transmission, 1992–2003.

Each unit is inspected for bore dimension and pressure integrity before packing. Because multiple cross-references circulate (CO24010, 8-97148-625-1, 8971486251), confirming the physical marking and bore size on the first sample is recommended before bulk commitment.

1. 1Safety first: Park on level ground, engage the parking brake, and chock the wheels. The clutch system is hydraulically operated — do not open the hydraulic circuit while the system is under pressure.
2. 2Locate the slave cylinder: On ISUZU N-Series trucks, the slave cylinder is mounted on the transmission bellhousing, actuating the clutch release fork.
3. 3Disconnect the hydraulic line: Place a drain pan underneath, disconnect the fluid line from the slave cylinder, and plug the line immediately to prevent contamination and fluid loss.
4. 4Remove the mounting bolts: Unbolt the slave cylinder from the transmission. Note the orientation of the pushrod and any return spring.
5. 5Compare new and original: Verify that the replacement has the same 1" bore, pushrod length, and mounting flange orientation as the original unit.
6. 6Bench-bleed the slave cylinder (recommended): Fill the cylinder with clean clutch fluid and bleed it on the bench before installation to reduce in-vehicle bleeding time.
7. 7Install the new cylinder: Position the slave cylinder on the transmission, insert the mounting bolts, and torque to the workshop manual specification.
8. 8Reconnect the hydraulic line: Connect the fluid line and tighten the fitting without over-torquing.
9. 9Bleed the clutch system: Fill the clutch master cylinder reservoir with the specified fluid. Bleed the slave cylinder according to the ISUZU procedure until clear, bubble-free fluid flows from the bleeder screw. Air in the circuit is the leading cause of post-replacement clutch drag and hard shifting.
10. 10Test operation: With the engine running, depress the clutch pedal and verify smooth gear engagement in all gears. The pedal should return fully and the vehicle should not creep when the clutch is depressed and a gear is selected.

• Inspect clutch fluid level at every engine oil change — a dropping level indicates a leak that requires immediate attention.
• Flush clutch fluid every 2 years or according to the ISUZU schedule — degraded fluid accelerates seal wear in both the master and slave cylinders.
• Check for leaks at the slave cylinder body, bleeder screw, and hydraulic line fitting during routine inspection.
• Replace the slave cylinder at the first sign of a spongy pedal or external leak — do not "top up and monitor" a known-failing hydraulic component on a commercial vehicle.

• Standard packing: Neutral box / color box / customer-branded packaging available. Confirm whether the package includes the pushrod or is cylinder-only at inquiry.
• Package contents: 1 × Clutch Slave Cylinder (pushrod and mounting hardware not included unless explicitly stated).
• Set options: Slave cylinder only / clutch operating kit (e.g., SB COK24006 reference) — specify at inquiry.
• Suitable for: ISUZU NPR/NKR/NPS clutch repair shops, fleet maintenance departments, commercial truck spare parts distributors, and export wholesalers serving Southeast Asia, the Middle East, Africa, and Latin America.
• Related parts available: Clutch master cylinder, clutch release bearing, clutch disc, pressure plate, and clutch fluid for the 4HF1 / 4HG1 / 4HE1 NPR/NKR platform.