11 Teeth Starter Pinion Clutch Assembly 8-97025671-0 8970256710 OEM Standard Size Starter Overrunning Clutch for ISUZU NPR66 NKR66 NKS58 4HF1 4BE1

The Starter Pinion Clutch Assembly with OEM numbers 8-97025671-0 / 8970256710 is a verified direct-fit replacement for ISUZU NPR66, NKR66, NKS58, NQR71, and NQR75 trucks equipped with 4HF1, 4BE1, and 4HG1 diesel engines. This assembly (CLUTCH ASM; PINION, STARTER) is the starter overrunning clutch (commonly known as "starter drive" or "Bendix"), installed at the starter drive end. It transmits the starter motor's rotational power to the engine flywheel ring gear during cranking and automatically disengages after engine start to prevent the starter from being back-driven and damaged.

The starter pinion clutch is continuously subjected to high torque impact during cranking and frequent engagement wear. When the internal overrunning clutch slips, gear teeth wear, or the mechanism seizes, it leads to starter free-spinning, weak cranking, or failure to start. Timely replacement restores proper starter operation.

Replaces ISUZU OEM numbers:

• 8-97025-671-0 / 8970255710
• 8-97025-672-0 / 8970256720
• 8-97161-793-0 / 8971617930

International brand alternatives include:

• HITACHI 2240-2501 / 2240-6501
• SUN AUTO 151252
• CARGO 234866 / F032234866
• KRAUF SDH4866 / SDH5866
• GHIBAUDI 6171
• NN 3-5361-W / IA2834
• WIX SD-4866

When the starter pinion clutch exhibits the following conditions, timely inspection and replacement are required:

1. Starter spins freely without cranking the engine: Starter motor runs normally but engine does not turn; overrunning clutch slipping or gear not engaging flywheel ring gear.
2. Sharp metallic grinding noise during cranking: Worn gear teeth or abnormal engagement clearance, producing harsh "grinding" sound at startup.
3. Weak or intermittent starter operation: Worn internal rollers in overrunning clutch, reduced torque transfer capability, inconsistent cranking performance between cold and hot conditions.
4. Starter gear fails to retract or seizes: Gear cannot disengage from flywheel ring gear after engine starts, causing starter back-drive noise and potential damage.
5. Severe gear tooth wear or broken teeth: Visible wear, pitting, or broken teeth on gear surface, preventing proper engagement with flywheel ring gear.

Certification: Manufacturer holds ISO/TS16949 automotive quality management system certification. Products undergo 100% testing before shipment.

1. Disconnect power: Disconnect negative battery terminal before installation to prevent electrical short circuits.
2. Remove starter: Remove starter mounting bolts, disconnect starter power cable, remove starter from engine.
3. Disassemble starter: Remove starter end cover, extract old pinion clutch assembly. Note component positions.
4. Inspect related components: Check flywheel ring gear wear, starter fork, and bearing condition; replace if necessary.
5. Install new clutch: Position new pinion clutch assembly, ensuring gear slides smoothly on starter shaft.
6. Reassemble starter: Reinstall starter end cover, tighten mounting bolts to specified torque.
7. Install starter: Reinstall starter to engine, connect power cable, tighten mounting bolts to specified torque.
8. Function test: Restore battery connection, start engine, check starter operation for abnormal noise, and confirm gear retracts properly after start.

• Every 50,000 km or 12 months: Check starter cranking performance and for abnormal noise.
• Every 100,000 km: Inspect starter pinion and flywheel ring gear wear; replace if necessary.
• When starter free-spinning or abnormal cranking noise is detected: Inspect pinion clutch condition promptly to prevent flywheel ring gear damage.