Crankshaft Damper Pulley 8972220311 8970884774 8-97222031-1 8-97088477-4 for ISUZU NPR66 4HF1 — OEM Quality

The Crankshaft Damper Pulley (Harmonic Balancer) with OEM numbers 8972220311 / 8-97222031-1 and 8970884774 / 8-97088477-4 is a verified direct-fit replacement for ISUZU NPR66 series trucks equipped with 4H series engines (including 4HF1, 4HG1/T). This damper pulley is a critical engine component mounted at the front of the crankshaft, performing two core functions: torsional vibration damping and engine accessory drive.

The crankshaft damper pulley (harmonic balancer) consists of two core elements: a mass (metal inner core) and an energy-dissipating element (rubber outer ring). As the engine runs, the crankshaft generates torsional vibrations. The rubber outer ring absorbs and dissipates vibration energy through its damping properties, significantly reducing torsional stress on the crankshaft. Simultaneously, the pulley grooves drive engine front-end accessories — alternator, water pump, air conditioning compressor, etc. — ensuring normal operation of each accessory system.

• Excessive Engine Vibration — Noticeably increased engine vibration at idle or acceleration (rubber aging, loss of damping effect)
• Belt Squealing — High-pitched squealing noise during engine operation (pulley surface wear or rubber cracking)
• Rubber Cracking/Bulging — Visual inspection reveals cracks, bulges, or separation of the rubber outer ring
• Accessory Malfunction — Poor alternator charging, engine overheating (insufficient water pump speed), weak A/C cooling
• Premature Crankshaft Bearing Wear — Ineffective vibration damping accelerates main bearing and connecting rod bearing wear
• Premature Belt Failure — Worn pulley grooves cause belt slippage or abnormal wear

Refer to workshop manual for detailed procedures:

1. Safety Prep — Disconnect battery negative terminal; ensure engine is cooled
2. Remove Drive Belt — Release tensioner; remove drive belt
3. Remove Old Pulley — Use special tool to hold crankshaft; remove crankshaft center bolt; remove old pulley
4. Clean Mounting Surface — Thoroughly clean crankshaft front end and pulley mounting surface
5. Inspect Crankshaft Key — Check crankshaft Woodruff key for wear; replace if damaged
6. Install New Pulley — Align timing marks and keyway; install new pulley onto crankshaft
7. Tighten Center Bolt — Torque crankshaft bolt to workshop manual specification (must use torque wrench)
8. Install Drive Belt — Reinstall drive belt; adjust tension to specification
9. Verify Timing — Confirm all timing marks are properly aligned
10. Test Run — Start engine; check for abnormal noise and vibration

• Packaging: Neutral carton / Color box / Custom branded packaging
• Packaging Unit: 1 piece/box
• Unit Weight: 4.866kg
• HS Code: 848350000
• MOQ: Small orders accepted (1 piece MOQ); volume discounts available
• Target Customers: Truck parts wholesalers, repair chain stores, fleet purchasers, cross-border e-commerce sellers