ISUZU NPR NKR 4BG1 Heat-Resistant Alloy Steel Exhaust Valve with 37.5 mm Head

Exhaust Valve 8-97028706-0 8970287060 for ISUZU NPR NKR 4BG1 6BG1 4BD1 — Verified OEM Fit 37.5*9*127.8 mm Heat-Resistant Alloy Steel Engine Valve

The Exhaust Valve with OEM numbers 8-97028706-0 and 8970287060 is a verified direct-fit replacement for ISUZU NPR / NKR / ELF / FSR trucks and Hitachi ZX120 / ZX200 excavators equipped with 4BG1 / 4BG1T / 6BG1 / 6BG1T / 4BD1 diesel engines. This exhaust valve is a critical component of the cylinder head assembly, responsible for managing the outflow of combustion gases from the engine cylinders at precisely timed intervals.

The exhaust valve opens at a precise moment during the engine cycle to release spent exhaust gases into the exhaust manifold, then closes at the exact time to maintain engine efficiency during the intake stroke. This precise timing is crucial for maintaining proper engine breathing, enhancing power production, and minimizing back pressure. ISUZU genuine exhaust valves are manufactured from high-grade heat-resistant alloy steel to withstand combustion temperatures exceeding 800°C and continuous high-speed opening and closing cycles. Many designs feature a hardened stem tip and a precision-ground head manufactured to exacting dimensional tolerances.

• Engine misfiring or rough running — a burned or warped valve cannot seal properly, causing compression loss and misfiring
• Loss of power and reduced fuel economy — a leaking exhaust valve reduces engine efficiency and power output
• Excessive exhaust smoke or unusual exhaust noise — a damaged valve allows combustion gases to escape improperly
• Valve clearance out of specification — valve clearance changes indicate valve face or seat wear
• Visible burning, cracking, or warping on the valve head — indicates the valve has exceeded its service life and must be replaced

1. Preparation: Remove the cylinder head from the engine. Clean the cylinder head thoroughly. Remove all old valves, springs, and seals
2. Inspection: Inspect the valve guides for wear. Measure the valve guide bore and compare to specification. Inspect the valve seats for pitting or erosion. Replace or recondition as necessary
3. Valve Installation: Lubricate the new valve stem with clean engine oil. Insert the valve into the guide. Install the valve spring, retainer, and keepers
4. Valve Clearance Adjustment: Set the cold valve clearance to 0.40 mm (0.0157 in). Adjust the rocker arm screw until the feeler gauge slides with slight drag
5. Cylinder Head Installation: Install the cylinder head with a new gasket. Torque the head bolts in the specified sequence and stages
6. Final Check: Rotate the engine by hand to verify smooth valve operation. Check for any binding or interference
7. Engine Start: Start the engine and check for abnormal noise or exhaust smoke. Verify proper valve operation

• Every 1,200 operating hours: Adjust valve clearance. Inspect valve train for abnormal noise
• Every 40,000–50,000 km: Inspect valve guides and seats. Check valve stem wear
• When engine performance degrades: Test compression and inspect valves immediately
• At engine overhaul: Always replace valves, guides, and springs as a complete set

• Standard Packaging: Anti-rust oil + VCI film + neutral carton
• 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
• Minimum Order Quantity: 10 PCS