Alloy Steel Construction ISUZU Crankshaft for 4BC2 Engine with Precision Journal Machining
Alloy Steel Construction ISUZU Crankshaft for 4BC2 Engine with Precision Journal Machining
Key Attributes
Brand Name:YIMI
Model Number:NPR 4BC2
Place of Origin:CHINA
Certification:ISO/TS16949
Minimum Order Quantity:20 PCS
Price:Negotiable
Supply Ability:10000 pcs/month
Delivery Time:5-8 Work Days
Payment Terms:T/T
Standard Packaging:Neutral Package or as customers’ request
Product Summary
ISUZU NPR 4BC2 Crankshaft 5123101612 5-12310161-DG OEM Fit Crankshaft 5123101612 5-12310161-DG for ISUZU NPR 4BC2 Diesel Engine — Verified OEM Fit for 3.3L 4-Cylinder Crankshaft Assembly The Crankshaft with OEM numbers 5123101612 and 5-12310161-DG is a verified direct-fit replacement for ISUZU NPR ...
Product Details
Highlight:
Alloy Steel Construction Crankshaft
,4BC2 Engine Compatibility ISUZU Crankshaft
,Precision Journal Machining Engine Crankshaft
Engine Displacement:
3,268 Cc
Connecting Rod Journal Diameter:
64 Mm
Eccentric Diameter:
50 Mm
Overall Length:
647 Mm
Main Journal Diameter:
70 Mm
Net Weight:
28.1 Kg
Product Description
Detailed Specifications & Features
ISUZU NPR 4BC2 Crankshaft 5123101612 5-12310161-DG OEM Fit
Crankshaft 5123101612 5-12310161-DG for ISUZU NPR 4BC2 Diesel Engine — Verified OEM Fit for 3.3L 4-Cylinder Crankshaft Assembly
The Crankshaft with OEM numbers 5123101612 and 5-12310161-DG is a verified direct-fit replacement for ISUZU NPR trucks equipped with the 4BC2 3.3L diesel engine. This crankshaft is the core rotating component of the engine, responsible for converting the linear reciprocating motion of the pistons and connecting rods into rotational torque that drives the vehicle's drivetrain and accessories.
Working Principle
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 4BC2 engine is known for its robust internal components — with basic maintenance, these engines commonly exceed 500,000 miles (800,000+ km), and the crankshaft is a key contributor to this durability.
Failure Symptoms
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.
Critical Inspection Note: ISUZU service manuals require that the crankshaft be inspected for journal roundness, taper, and surface finish during any engine overhaul. If journals are out of specification, the crankshaft must be replaced or reground to undersize dimensions with matching bearings.
Technical Specifications
| Verification Item | Data / Standard | Source / Method |
|---|---|---|
| Part Number (Short) | 5123101612 | ISUZU OEM Parts Database |
| Factory Number | 5-12310161-DG | ISUZU OEM Parts Database |
| Part Name | Crankshaft | ISUZU EPC |
| Engine Compatibility | 4BC2 (3.3L, 4-cylinder, OHV, DI) | ISUZU application catalog |
| Vehicle Models | ISUZU NPR / NKR / KT / TLD | ISUZU application catalog |
| Eccentric Diameter | 50 mm | Gasgoo crankshaft specification table |
| Main Journal Diameter | 70 mm | Gasgoo crankshaft specification table |
| Connecting Rod Journal Diameter | 64 mm | Gasgoo crankshaft specification table |
| Overall Length | 647 mm | Gasgoo crankshaft specification table |
| Net Weight | 28.1 kg | Product specification |
| Material | Alloy Steel | Material certificate |
| Package Size | 72 * 21.5 * 18 cm | Product specification |
| Crankshaft Bearing Cap Bolt Torque | 225.4–245.0 N·m | ISUZU 4BC2 workshop manual |
| Connecting Rod Bearing Bolt Torque | 78.4–88.2 N·m | ISUZU 4BC2 workshop manual |
| Warranty | 6 Months | Manufacturer standard |
| Certification | ISO/TS 16949 | Third-party system audit |
OEM Cross-Reference
| Type | Number |
|---|---|
| Primary OEM — Short | 5123101612 |
| Factory Number | 5-12310161-DG |
| Alternate Format | 5-12310161-0 |
| Alternate Format | 5-12310-161-0 |
| Alternate Format | 5123101610 |
| Related Crankshaft — 4BD1 | 5123101630 |
| Related Crankshaft — 4BE1 | 8944163732 |
Vehicle & Engine Compatibility
Primary Applications
| Brand | Model | Chassis | Engine | Years |
|---|---|---|---|---|
| ISUZU | ELF | NKR | 4BC1 / 4BC2 | 1982–1987 |
| ISUZU | NPR | NPR | 4BC2 | 1982–1987 |
| ISUZU | NPR | NPR | 4BC1 / 4BC2 / DB33 | 1985–2024 |
| ISUZU | KT | KT | 4BC2 | 1982–1987 |
| ISUZU | TLD | TLD | 4BC2 | 1982–1987 |
Important Fitment Notes:
- The 4BC2 crankshaft is a forged or cast alloy steel component. Verify the crankshaft journal dimensions against the old unit before ordering.
- The 4BC2 engine was sold in ISUZU ELF and NPR trucks from 1982 to 1987, and continued in various applications through 2024. Confirm your specific engine model and year.
- For engines that have been previously reground, verify the current journal diameter before ordering a standard-size 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.
Features & Benefits
| Feature | Benefit + Verification Signal |
|---|---|
| Alloy Steel Construction | High tensile strength and fatigue resistance for reliable power transmission — verified by material certificate and hardness testing. |
| Precision Journal Machining | Uniform journal surfaces ensure proper bearing clearance and oil film formation — verified by CMM dimensional inspection. |
| 4BC2-Specific Dimensions (50/70/64/647 mm) | Direct drop-in fit for ISUZU NPR 4BC2 engines without modification — verified against Gasgoo crankshaft specification table. |
| Dynamic Balancing | Reduces vibration and abnormal wear, extending engine life — verified by dynamic balancing equipment. |
| Heat Treatment | Surface hardening for wear resistance on journals — verified by hardness testing. |
| ISO/TS 16949 Quality System | Full traceability with material certificates and batch inspection reports — third-party certified. |
Quality Control & Verification
| QC Item | Verification Method / Standard |
|---|---|
| Journal Diameters (Eccentric / Main / Rod) | CMM, 100% inspection |
| Overall Length | CMM, 100% inspection |
| Journal Roundness & Taper | Roundness tester, 100% inspection |
| Surface Hardness | Rockwell hardness tester, batch sampling |
| Dynamic Balance | Dynamic balancing machine, 100% inspection |
| Material Composition | Spectrometer analysis, batch sampling |
| Surface Finish (Ra) | Surface roughness tester, 100% inspection |
| Crack Detection | Magnetic particle inspection (MT), 100% inspection |
| Keyway Dimensions | CMM, 100% inspection |
| Thread Inspection (Flywheel / Pulley) | Thread gauge, 100% inspection |
| Batch Traceability | Material lot number + production date |
| Packaging Protection | Anti-rust oil + VCI film + wooden case |
Installation & Maintenance Recommendations
IMPORTANT: Crankshaft installation is an engine overhaul-level operation. It must be performed by a qualified diesel engine technician in a clean workshop. All bearing clearances must be measured with Plastigauge or micrometer before final assembly.
Installation Guidelines — Reference ISUZU 4BC2 Workshop Manual
- Preparation: Remove the engine from the vehicle. Disassemble the engine and remove the old crankshaft. Clean the cylinder block main bearing bores thoroughly.
- Bearing Installation: Install new main bearings into the cylinder block and bearing caps. Apply clean engine oil to all bearing surfaces.
- Crankshaft Installation: Carefully lower the crankshaft into the block. Install the bearing caps in their original positions with the arrows facing the correct direction.
- Torque Sequence: Tighten the crankshaft bearing cap bolts to 225.4–245.0 N·m in the numerical order specified in the workshop manual, a little at a time in stages.
- Connecting Rod Installation: Install the connecting rods and pistons. Tighten the connecting rod bearing bolts to 78.4–88.2 N·m.
- End Play Check: Measure crankshaft end play with a dial indicator. Ensure it is within the workshop manual specification.
- Rotation Check: Rotate the crankshaft by hand to verify smooth rotation without binding.
- Final Assembly: Install the flywheel, pulley, and other accessories. Torque all fasteners to specification.
Recommended Torque Values:
| Fastener | Torque |
|---|---|
| Crankshaft Bearing Cap Bolts | 225.4–245.0 N·m |
| Connecting Rod Bearing Bolts | 78.4–88.2 N·m |
Maintenance Schedule
- 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.
Packaging & Supply
- Standard Packaging: Anti-rust oil + VCI film + wooden case.
- Custom Packaging: Neutral packaging, customer-branded packaging.
- Suitable For: Engine overhaul workshops, ISUZU parts distributors, fleet maintenance centers.
- Supply Capacity: Stable batch supply with batch-level quality reports available.
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