Engine Connecting Rod Assembly 8-97388921-0 8973889210 For ISUZU 4JJ1 4JK1 NKR NLR NMR NNR D-Max MU-X — OEM Verified Forged Steel, 34mm Bushing, Staggered Bearing Holes

The Engine Connecting Rod Assembly with OEM references 8-97388921-0 / 8973889210 is a verified direct-fit replacement for ISUZU 4JJ1 (3.0L) and 4JK1 (2.5L) 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 4JJ1 is a 2,999 cc inline-4 DOHC common-rail diesel engine widely used in ISUZU NKR, NLR, NMR, NNR, D-Max, and MU-X vehicles, as well as in Hitachi, JCB, and Case construction equipment.

This connecting rod features a 34 mm small-end bushing for the full-floating piston pin, a forged steel construction for high fatigue strength, and a distinctive "staggered" bearing hole design — the oil feed holes in the big end are offset rather than aligned, which is a key identification feature for this 4JJ1/4JK1 conrod family. The rod body uses an I-beam (or H-beam for high-strength variants) cross-section to balance stiffness against reciprocating mass.

• OEM Cross-Reference Verified: The 8-97388921 family is confirmed across 8973889210, 8973889211, 8973889212, 8973889213, 8-97388921-0, -1, -2, -3, and 02/802474 (JCB reference) in multiple independent catalogs.
• Bushing Specification Verified: 34 mm small-end bushing — confirmed by supplier technical listing for the 8973889212 reference. Performance rod data for the 4JJ1 also lists a 34.00 mm small-end bore.
• Bearing Hole Design Verified: "Bearing Holes Staggered" (轴承孔错位) — a distinctive feature explicitly listed for this conrod family.
• Material Verified: Steel / forged steel — confirmed by supplier material specification, with performance-grade 4JJ1 rods using forged 4340 chrome-moly steel as a reference for the platform's material expectations.
• Weight Verified: 1.2 kg per rod (reference weight, without bearings) — confirmed by supplier listing for the 8973889212 reference.
• Dimensional Reference Verified: Center-to-center length 158 mm, big-end bore 56.00 mm, big-end width 33.00 mm, small-end bore 34.00 mm, small-end width 33.00 mm — confirmed by performance connecting rod data for the ISUZU 4JJ1 3.0L platform.
• Multi-Platform Coverage Verified: Compatible with ISUZU 4JJ1 / 4JK1 engines and applications including NKR, NLR, NMR, NNR, TFR, TFS, D-Max, MU-X, plus Hitachi ZX110-3 through ZX180LC-3, ZX220, ZX230, ZX240, ZX330, ZX350 excavators, JCB JS/JZ series, and Case CX series.

• 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.
• Excessive piston pin noise (double knock): A worn 34 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.

1. Confirm original rod dimensions: Measure the removed rod's center-to-center length, big-end bore/width, small-end bushing bore (34 mm), and bearing hole orientation (staggered). Match the new rod to these dimensions exactly.
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. Fit or verify the small-end bushing: If the bushing is not pre-fitted, press in the new bushing and ream/hone to the specified 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 lock tangs engage the lock slots. 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 34 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.
• 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 bearing hole orientation across all cylinders to maintain engine balance.

• Standard packing: Neutral carton with protective wrapping; wooden pallet available for bulk export orders.
• 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 4JJ1/4JK1) — specify at inquiry.
• Suitable for: ISUZU engine rebuilders, Hitachi / JCB / Case equipment repair shops, commercial truck and pickup fleet maintenance departments, spare parts distributors, and export wholesalers.
• Related parts available: Rod bearings, small-end bushings, piston pins, rod bolts, piston kits (95.4 mm for 4JJ1), and complete 4JJ1 / 4JK1 overhaul kits.