GT2256MS Model Turbocharger Assembly for ISUZU 4HG1 Engine with Oil-Cooled and Water-Cooled Design

Turbocharger Assembly 8-97326752-0 8973267520 GT2256MS for ISUZU NKR NPR NQR NPS 4HG1 4HG1-T — Verified OEM Fit Complete Turbocharger with Wastegate Actuator

The Turbocharger Assembly with OEM numbers 8-97326752-0 and 8973267520 is a verified direct-fit replacement for ISUZU NKR / NPR / NQR / NPS / NPR71 / NPR250 / NLR / NMR / NNR light and medium-duty trucks, as well as Bogdan A-091 / A-092 buses equipped with 4HG1 / 4HG1-T diesel engines. This turbocharger is a critical component of the engine's forced induction system, responsible for compressing intake air to increase engine power output, improve fuel efficiency, and reduce exhaust emissions.

The turbocharger is an exhaust gas-driven forced induction device that increases the volumetric efficiency of the diesel engine. Exhaust gases from the engine flow through the turbine housing, spinning the turbine wheel. The turbine wheel is connected by a shaft to the compressor wheel, which draws in ambient air through the air filter and compresses it before it enters the intake manifold. This compressed air — cooled by the intercooler — allows the engine to burn more fuel, producing more power without increasing engine displacement. The GT2256MS turbocharger features a wastegate actuator that regulates boost pressure by bypassing exhaust gases around the turbine when the preset boost limit is reached, preventing over-boosting and protecting the engine. The turbocharger is both oil-cooled and water-cooled for optimal thermal management under heavy-duty operation, with an integrated exhaust manifold for simplified installation and reduced leak points.

• Low boost / sluggish power — worn bearings, damaged wheels, or a stuck wastegate reduce turbocharger output, causing noticeable power loss and sluggish acceleration.
• Whining, siren, or rattle noise — imbalanced wheels or excessive shaft play indicate imminent turbocharger failure.
• Oil in charge pipes or intercooler — seal failure allows oil carryover into the intake system, fouling the intercooler and causing blue exhaust smoke.
• Black or blue exhaust smoke — inefficient boost or oil leakage through the turbocharger causes visible exhaust smoke.
• Overheating / high exhaust gas temperatures (EGTs) — ineffective turbocharger flow increases exhaust temperatures under load, potentially damaging exhaust valves and pistons.
• Loss of power under load — the engine loses power when climbing hills or accelerating with a load, indicating insufficient boost pressure.

1. Preparation: Disconnect the battery negative terminal. Drain the engine oil and coolant. Remove the air intake hose, exhaust pipe, and oil feed/return lines from the turbocharger.
2. Removal: Remove the turbocharger mounting bolts and nuts. Carefully withdraw the turbocharger assembly from the exhaust manifold. Remove the old gaskets and clean all mating surfaces.
3. Inspection: Inspect the exhaust manifold for cracks or warping. Inspect the oil feed and return lines for blockages or debris. Inspect the intercooler and charge pipes for oil contamination and clean thoroughly.
4. Preparation for New Turbocharger: Prime the new turbocharger with fresh clean engine oil through the oil inlet port. Rotate the compressor wheel by hand to distribute the oil.
5. Installation: Install the new turbocharger with new gaskets. Tighten the turbine housing tie-down bolts to 22 N·m (2.2 kg·m / 16 lb·ft). Install the oil feed line (new), oil return line (new), and coolant lines.

• Every 10,000 km: Check engine oil level and condition. Inspect turbocharger for oil leaks.
• Every 20,000 km: Check boost pressure and wastegate actuator operation. Inspect charge pipes for oil residue.
• Every 40,000–50,000 km: Inspect turbocharger shaft play and compressor wheel condition. Replace air filter.
• When low power or smoke is detected: Test boost pressure immediately. Inspect turbocharger for damage.
• Always use high-quality engine oil and change at recommended intervals to protect the turbocharger bearings.

• Standard Packaging: Anti-rust oil + VCI film + neutral carton + wooden case.
• Custom Packaging: Neutral box, color box, or customer-branded packaging.
• Suitable For: Turbocharger repair shops, ISUZU parts distributors, fleet maintenance centers, bus fleet operators.
• Minimum Order Quantity: 2 PCS