8-97071673-0 OEM Fit Valve Push Rod Engine Push Rod for ISUZU 4JH1 4JB1 4JG2 with Hardened End Tips

Valve Push Rod 8-97071673-0 / 8970716730 — a verified OEM-fit engine valve tappet rod for ISUZU NKR77, NPR, NKR55, NHR, NLR, NMR series trucks equipped with 4JH1, 4JB1, 4JG2, 4JA1, and 4JC1 diesel engines.

This push rod is a critical transmission element of the engine valvetrain, responsible for precisely transferring camshaft motion to the valve and controlling valve opening and closing timing.

The valve push rod is a rigid rod that connects the camshaft (via the tappet) to the rocker arm, or directly actuates the valve in the valvetrain. As the camshaft rotates, the cam lobe lift pushes the tappet, which in turn drives the push rod in reciprocating linear motion. The push rod then transmits this motion to the rocker arm, ultimately opening and closing the valve according to the valve timing requirements.

The push rod must possess both high axial stiffness (to prevent bending that would cause valve timing errors) and lightweight construction (to reduce reciprocating inertia forces). Both ends are typically hardened to resist high-frequency wear at the contact surfaces with the tappet and rocker arm.

The 4JH1 is a 3.0L inline-four diesel engine and the 4JB1 is a 2.8L inline-four diesel engine, both widely used in ISUZU NKR/NPR series trucks and extensively applied in Hitachi, JCB, Doosan and other construction equipment.

Replace the push rod when any of these symptoms appear:

• Engine abnormal noise (tapping or knocking) — a bent or worn push rod causes excessive valve clearance, producing metallic tapping noise.
• Engine misfire or power loss — a bent push rod results in insufficient or no valve lift, causing inadequate cylinder intake/exhaust.
• Frequent valve clearance changes — worn or bent push rod ends prevent stable valve clearance retention.
• Visible bending, cracks, or severe end wear on the push rod — the push rod has exceeded its elastic or wear limit and must be replaced.
• Engine backfire or abnormal exhaust — push rod failure causes valve timing misalignment, leading to intake backfire or black exhaust smoke.
• Metal debris in the valvetrain area — metal particles from abnormal push rod end wear contaminate the engine oil.

📌 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. 1Preparation: Remove the cylinder head cover. Remove the rocker shaft assembly or rocker arms. Extract the old push rods.
2. 2Inspection: Roll each push rod on a flat surface to check straightness; inspect both end faces for wear, pitting, or cracks. Inspect tappet ends and rocker arm adjusting screw ends for wear. Check valve guides for excessive wear.
3. 3Installation: Clean the push rods and installation bores. Apply clean engine oil to both ends of the push rods. Insert the new push rods into the block bores, ensuring the lower ends seat securely in the tappet sockets (or seats).
4. 4Rocker Arm Installation: Install the rocker shaft assembly or rocker arms and torque the retaining bolts to specification.
5. 5Valve Clearance Adjustment: Adjust valve clearance to the cold specification per the workshop manual (using the "cylinder-by-cylinder" or "two-position" method).
6. 6Final Check: Rotate the engine by hand two full turns to verify the push rods are free from binding or disengagement. Check all fastener torques.
7. 7Road Test: Start the engine and check for abnormal noise or misfire, then perform a road test.

• Every 10,000 km: Check for abnormal valvetrain noise. Check engine oil level and condition.
• Every 40,000–50,000 km: Check/adjust valve clearance. Inspect push rod end wear.
• Every 100,000 km: Inspect push rod straightness and end wear during cylinder head service.
• When valvetrain noise is detected: Inspect push rods, tappets, and rocker arms immediately.
• At any cylinder head service: Always inspect push rods and replace if any abnormality is found.

• Standard Packaging: Anti-rust oil + VCI film + neutral carton (5 PCS/bag).
• Custom Packaging: Neutral box, color box, or customer-branded packaging.
• Suitable For: Engine repair shops, ISUZU parts distributors, construction equipment repair shops, fleet maintenance centers.
• Supply Capacity: Stable batch supply with batch-level quality reports available.
• MOQ: 5 PCS (1 bag).