8-97112981-0 OEM Fit Engine Crankshaft 4HF1 4HG1 Engine Compatibility Forged Steel Crankshaft Assembly for ISUZU NPR NKR NQR

Verified direct-fit forged steel crankshaft assembly for ISUZU NPR / NKR / NQR trucks equipped with 4HF1 / 4HG1 diesel engines. OEM references 8-97112981-0 and 8971129810. Dimensions: 82 × 66 × 661 mm.

The crankshaft is the core rotating component of the engine. It converts the linear reciprocating motion of the pistons and connecting rods into rotational torque that drives the vehicle's drivetrain and accessories.

The crankshaft is the most critical component in the engine's power conversion process. It receives force from the connecting rods and converts it into torque, which is transmitted through the crankshaft to drive the vehicle and operate engine accessories. The crankshaft must have sufficient strength and rigidity, and its journal surfaces must be wear-resistant, uniform, and balanced.

The 4HF1 is a 4.3L inline-four direct-injection diesel engine and the 4HG1 is a 4.6L variant. Both are widely used in ISUZU NPR/NKR series trucks and are extensively applied in Hitachi, JCB and other construction equipment.

This crankshaft is manufactured from forged steel (or cast iron), processed through CNC machining, multi-stage heat treatment (nitriding/quenching), shot peening, and polishing, achieving a surface hardness of up to HRC 55 (42CrMo steel, nitrided). This ensures excellent fatigue strength and journal wear resistance under high-load conditions.

Replace the crankshaft when any of these symptoms appear:

• Heavy knocking noise from the bottom end of the engine — worn main bearings or connecting rod bearings allow excessive crankshaft movement.
• Abnormal engine vibration — imbalance, wear, or scoring on the crankshaft journals causes vibration throughout the engine operating range.
• Low oil pressure — worn crankshaft journals increase bearing clearance, reducing oil pressure and triggering the warning light.
• Metal debris in the oil pan — bearing material particles indicate crankshaft journal wear or scoring.
• Engine seizing or inability to rotate — severe bearing failure or thrust bearing wear can seize the crankshaft.

📌 Fitment Verification: To ensure 100% accurate matching, please provide the VIN or chassis number before ordering. We will verify it through the ISUZU global EPC system.

1. Preparation: Remove the engine from the vehicle. Disassemble the engine and remove the old crankshaft. Clean the cylinder block main bearing bores thoroughly.
2. Bearing Installation: Install new main bearings into the cylinder block and bearing caps. Apply clean engine oil to all bearing surfaces.
3. Crankshaft Installation: Carefully lower the crankshaft into the block. Install the bearing caps in their original positions with the arrows facing the correct direction.
4. Torque Sequence: Tighten the crankshaft bearing cap bolts in the numerical order specified in the workshop manual, a little at a time in stages.
5. Connecting Rod Installation: Install the connecting rods and pistons. Tighten the connecting rod bearing bolts to specification.
6. End Play Check: Measure crankshaft end play with a dial indicator. Ensure it is within the workshop manual specification.
7. Rotation Check: Rotate the crankshaft by hand to verify smooth rotation without binding.
8. Final Assembly: Install the flywheel, pulley, and other accessories. Torque all fasteners to specification.

• Every 5,000–10,000 km: Change engine oil and filter. Check oil pressure.
• Every 40,000–50,000 km: Perform oil analysis to detect bearing wear metals.
• At engine overhaul: Inspect crankshaft journals for wear, scoring, or cracks. Replace if out of specification.
• Whenever bearing failure occurs: Replace the crankshaft if journals are damaged or out of round.

• Standard Packaging: Anti-rust oil + VCI film + wooden case (approx. 72×21×16 cm).
• Custom Packaging: Neutral box, color box, or customer-branded packaging.
• Suitable For: Engine repair shops, ISUZU parts distributors, fleet maintenance centers, construction equipment repair shops.
• Supply Capacity: Stable batch supply with batch-level quality reports available.
• MOQ: 1 PCS