Engine Connecting Rod Assembly 8-97135032-0 8971350320 For ISUZU 4HG1 4HF1 4HL1 NKR NPR NQR NKS NPS — OEM Verified, 36mm Bushing, Staggered Bearing Notch, Heavy-Duty Diesel Conrod

The Engine Connecting Rod Assembly with OEM references 8-97135032-0 / 8971350320 is a verified direct-fit replacement for ISUZU 4HG1, 4HG1-T, 4HF1, and 4HL1 diesel engines. This connecting rod is the critical link between the piston and the crankshaft, transmitting combustion force from the piston pin to the crankshaft journal and converting linear piston motion into rotational power.

The 4HG1 and 4HF1 are 4.6L and 4.3L inline-4 diesel engines widely used in ISUZU NKR, NPR, NQR, NKS, NPS, FRR, FSR, and FRD commercial trucks from the late 1990s onward, as well as in industrial and engineering machinery applications powered by the 4H-series engine family.

This connecting rod features a 36 mm small-end bushing for the full-floating piston pin and a 66 mm big-end bearing bore, with a distinctive staggered bearing notch design — the bearing shell locking notches are positioned on different sides rather than aligned. This staggered configuration is a family-level identification feature for the 4HG1/4HF1/4HL1 conrod and is not interchangeable with same-side (aligned-notch) rods used in other ISUZU engine families such as the 4HK1/6HK1. The rod body uses an I-beam cross-section to balance stiffness against reciprocating mass, and the assembly is manufactured from high-strength alloy steel under ISO 9001 quality management.

• ✓Bushing & Bore Dimensions Verified: 36 mm small-end bushing inner diameter and 66 mm big-end bearing bore — confirmed across multiple independent supplier technical listings for the 8-97135032-0 / 8971350320 reference family.
• ✓Notch Design Verified: Staggered bearing notch ("Entalhe da bucha da haste em lados diferentes" / "Stagger Piston Pin Hole") — explicitly listed as a defining characteristic of this conrod, distinguishing it from same-side-lock ISUZU rods.
• ✓Material & Quality Verified: High-strength alloy steel with ISO 9001 certification — confirmed by supplier material and quality management specifications.
• ✓Weight Reference Verified: Multiple weight references exist across suppliers — 1.75 kg (Autopart-Masters family), 1.9 kg (Anqing Hengruixing / HRX), and 2 kg (Persian supplier listing). Weight matching within an engine set is mandatory; the specific batch weight should be confirmed at inquiry.
• ✓OEM Cross-Reference Verified: The 8-97135032 family is confirmed across 8971350320, 8971350321, 8971350322, 8971350323, 8944734436, and 8971350325 / CR032 in multiple independent catalogs. Aftermarket brand cross-references include D125020 and D125421 (Diesel brand).
• ✓Vehicle & Equipment Coverage Verified: Confirmed for ISUZU NKR, NPR, NQR, NLR, NKS, NPS, FRD, FRR, FSD, and FSR trucks with 4HF1 / 4HG1 / 4HL1 engines, and for engineering machinery powered by the 4H-series engine family.

• Deep metallic knocking from the engine block (rod knock): A worn large-end bearing or a stretched rod produces a heavy, rhythmic knock that intensifies under load and may diminish when the cylinder is disabled during diagnostics.
• Low oil pressure with metal debris in the oil: Bearing material suspended in the oil, often appearing as a glittering sheen, indicates rod bearing degradation — a documented failure path on high-mileage 4HG1/4HF1 engines.
• Excessive piston pin noise (double knock): A worn 36 mm small-end bushing produces a sharp double-knock at idle and low speed, especially on cold start.
• Bent or stretched rod after hydrolock or overheating: A rod subjected to liquid ingress or thermal distortion may be bent beyond specification even without visible cracking. Rods should be measured for bend and twist during any major overhaul.
• Visible cracking at the rod cap or beam: Cracks in the forged beam or at the cap mating surface require immediate replacement — a fractured rod can exit the block and destroy the engine.
• Uneven bearing wear pattern: A bent or twisted rod produces an asymmetric bearing contact pattern, indicating the rod itself must be replaced, not just the bearings.

• Staggered notch is the defining fitment boundary: This rod uses a staggered bearing notch design ("notches on different sides"). It is not interchangeable with same-side-lock rods used in 4HK1/6HK1 engine families (e.g., 8-98018425-2 / 8980184252). Confirm the notch orientation against the original rod before ordering.
• 36 mm bushing is a hard dimensional requirement: The small-end bushing inner diameter must match the vehicle's 36 mm piston pin. Some 4H-series variants may use a different bushing specification — measure the original bushing bore before committing to bulk orders.
• Weight matching is mandatory: Supplier reference weights range from 1.75 kg to 2 kg. When replacing rods, use a matched weight set across all four cylinders to maintain engine balance and avoid vibration.
• 4HG1 vs. 4HF1 vs. 4HL1: All three engine codes are covered by this conrod reference in the aftermarket. However, if the vehicle is a later 4HL1 or common-rail variant, verify the connecting rod part number against the engine serial number or original rod marking before ordering.
• Rod bolts are typically torque-to-yield (TTY): Many diesel connecting rod bolts are designed to be replaced, not reused. Confirm bolt specification and replacement requirement at inquiry.

1. Confirm original rod dimensions, notch orientation, and weight: Measure the removed rod's small-end bushing bore (36 mm), big-end bore (66 mm), and weight. Verify the staggered notch orientation matches the new rod. Do not rely on the OEM number alone — physical confirmation is essential.
2. Check rod bend and twist: Even a new rod should be verified on a rod alignment fixture before installation. A bent rod will destroy the bearing and may damage the crankshaft.
3. Install or verify the small-end bushing: If the bushing requires replacement, press in the new bushing and align the oil hole with the rod oil path. Ream/hone to the specified 36 mm piston pin clearance. Do not assume a drop-in fit.
4. Install bearings and lubricate: Seat the bearing shells in the rod and cap, ensuring the staggered notch tangs engage the corresponding lock slots correctly. Lubricate bearing surfaces and the crank journal with assembly lubricant.
5. Protect the crank journal: Use rod bolt guides or tape over the rod bolts during installation to prevent scratching the crankshaft journal.
6. Torque rod bolts correctly: Use new rod bolts where specified. Torque in stages to the workshop manual specification, and measure rod bolt stretch if required. Do not substitute torque for stretch on TTY bolts.
7. Check side clearance and oil clearance: Verify connecting rod side clearance on the crank journal and bearing oil clearance with plastigauge or micrometer measurement.
8. Verify piston pin fit: The 36 mm pin should slide through the bushing with the specified clearance. A pin that is too tight will seize; one that is too loose will knock.
9. Rotate and re-check: After torquing all rods, rotate the crankshaft through two full turns and confirm smooth rotation with no binding or interference.

• Oil changes: Use the correct diesel engine oil and adhere to ISUZU recommended intervals (typically 10,000–15,000 km for commercial applications). Degraded oil accelerates rod bearing wear.
• Oil pressure monitoring: A drop in oil pressure or the appearance of a knock warrants immediate investigation — do not continue operating with suspected rod bearing degradation.
• Overhaul inspection: At any major engine overhaul, measure rod bend/twist and inspect the small-end bushing and large-end bearing surfaces.
• Matched sets: When replacing rods, use a matched weight set and the same staggered notch orientation across all four cylinders to maintain engine balance and bearing retention integrity.

• Standard packing: Neutral carton with protective wrapping; wooden pallet available for bulk export orders. Supplier MOQ references range from 1 pc to 10 pcs depending on the source; sample orders are typically accommodated.
• Package contents: 1 × Connecting Rod Assembly (bearings, bushing, and rod bolts not included unless explicitly stated — confirm at inquiry).
• Set options: Single rod / matched set for one engine (4 pcs for 4HG1 / 4HF1 / 4HL1) — specify at inquiry.
• Suitable for: ISUZU engine rebuilders, NKR / NPR / NQR fleet maintenance departments, commercial truck spare parts distributors, and export wholesalers serving Southeast Asia, the Middle East, Africa, and Latin America.
• Related parts available: Rod bearings (8970458000 reference for 4HF1/4HG1 conrod bearing), small-end bushings, piston pins, rod bolts, piston kits, and complete 4HG1 / 4HF1 overhaul kits.