Water Outlet Pipe / Thermostat Cover 8-97034445-0 / 8970344450 For ISUZU NKR55 NHR 100P (4JB1 / 4JG2) — Aluminum & Plastic, 0.41 Kg, OEM-Spec

The unit is manufactured from aluminum and plastic materials — the aluminum cover provides excellent heat dissipation and resistance to deformation, while the plastic housing interfaces with the coolant circulation channel. The design is engineered to prevent coolant leakage and resist the deformation that can occur with plastic-only covers under sustained thermal cycling. The net weight is 0.41 kg, with actual dimensions of 17 × 11 × 12 cm and HS code 840999100.

This component is described variously as "Water Outlet Pipe" (Ống Nước Outlet / Tuyau de sortie d'eau), "Thermostat Cover" (Capa do termostato / TERMOSTATDEKSEL), and "Thermostat Assembly" (Termostato ASM) across different supplier catalogs. These terms converge on the same functional component — the thermostat housing / water outlet cover that seats the thermostat and provides the coolant outlet passage. Confirm the physical form against the original unit.

The unit uses aluminum for the cover (heat dissipation, anti-deformation) and plastic for the housing/circulation channel interface. This is not a cast-iron or all-aluminum housing. The aluminum cover design is specifically noted as resistant to deformation compared with plastic-only covers, reducing the risk of coolant leakage under thermal cycling.

The component is confirmed for 4JB1 and 4JG2 engines in NKR55, NHR55, and 100P applications. Confirm the engine code and chassis model before ordering — other ISUZU engine families use different thermostat housing configurations.

• ✅ OE Reference Group Verified: 8-97034445-0, 8970344450, 8-97034-445-0, 8-97034445-5 (factory number) are consistently grouped as interchangeable or related references across multiple supplier catalogs.
• ✅ Vehicle & Engine Coverage Verified: ISUZU NKR55 4JB1, 4JG2 — confirmed by French, Portuguese, and Vietnamese supplier listings. ISUZU NHR55 4JB1 and 100P — confirmed by Yishan factory data and isuzu-truckspares listings.
• ✅ Material Verified: Aluminum cover + plastic housing — confirmed by Yishan product specification ("aluminium og plastmaterialer, aluminiumdeksel varme... ikke lett a deformere"). One Portuguese listing describes the part as "TUBO; SAÍDA DE ÁGUA" (water outlet pipe), confirming the functional naming variation.
• ✅ Net Weight Verified: 0.41 kg — confirmed by Vietnamese and Portuguese supplier specifications.
• ✅ Actual Dimensions Verified: 17 × 11 × 12 cm — confirmed by Yishan factory data.
• ✅ HS Code Verified: 840999100 — confirmed by Vietnamese and Portuguese supplier data.
• ✅ Factory Number Verified: 8-97034445-5 — confirmed as the factory/tooling reference for the NHR55 4JB1 application.
• ✅ Warranty Reference: 6 months — confirmed by Yishan product specification.
• ✅ Application Year Range Verified: 1985 onward for ISUZU ELF (NKR, NHR) — confirmed by DLJ Auto Parts water outlet application data.
• ⚠️ Precise Bore / Port Diameter NOT Publicly Published: The accessible supplier data does not publish the thermostat cavity diameter or coolant port bore for 8-97034445-0. Measure the original unit or confirm against the thermostat part number before ordering if precision matching is required.

• Coolant leak at the thermostat housing / outlet pipe joint: Visible drips, dampness, or crusty residue (white/pink coolant crust) around the housing-to-cylinder-head interface or the outlet-to-hose connection — the most direct sign of a failed gasket, warped sealing surface, or cracked housing.
• Overheating or temperature fluctuation: A housing that does not seal correctly allows coolant loss or air ingress, disrupting thermostat operation and causing temperature instability, especially under load.
• Coolant residue on the engine block or under the vehicle: Dried coolant around the thermostat area indicates a slow weep that should be addressed before it becomes a sudden failure.
• Deformed or cracked plastic housing: The plastic housing can age, deform, or crack under sustained thermal cycling — a failure mode specifically noted in the product specification as a reason the aluminum cover design is preferred.
• Thermostat not seating properly: A distorted housing cavity can prevent the thermostat from sealing, causing continuous coolant bypass and extended warm-up times.
• Visible corrosion or pitting on the aluminum cover sealing surface: The aluminum cover can corrode at the coolant passage edges, preventing the gasket from sealing even when new.

• Engine code and chassis model are the first checks: This housing is confirmed for 4JB1 and 4JG2 engines in NKR55, NHR55, and 100P applications. Confirm the engine code and model year against the vehicle documentation before ordering.
• Housing only — thermostat is separate: This listing covers the housing/cover only. The thermostat element is not included and must be ordered separately if a complete repair is required.
• Component naming variation: This part is described as Water Outlet Pipe, Thermostat Cover, and Thermostat Assembly across different catalogs. Confirm the physical form (cover with outlet passage vs. full housing assembly) against the original unit.
• Vehicle coverage: Core applications are NKR55, NHR55, and 100P with 4JB1/4JG2. Provide the VIN for final confirmation in mixed-fleet applications.

1. Confirm the required part first: Verify the engine code (4JB1 / 4JG2) and chassis model (NKR55 / NHR55 / 100P). Confirm whether the replacement is a cover/pipe or a full housing assembly and that the outlet diameter and mounting points match the original unit.
2. Cold engine only: Allow the engine to cool fully before opening the cooling system. Drain coolant to a level below the thermostat housing.
3. Remove the old housing/cover: Disconnect the coolant hose from the outlet. Unbolt the housing/cover from the cylinder head. Note the orientation of the thermostat and any gaskets or seals.
4. Clean the mating surface: Remove all old gasket residue and corrosion from the cylinder head face and the housing sealing surface. A clean, flat surface is essential for a leak-free seal.
5. Inspect the thermostat: Check the thermostat for correct operation. Replace if stuck open or closed. Confirm the correct temperature rating for the application.
6. Install the new housing/cover with a new gasket: Seat a new gasket, position the 8-97034445-0 unit, and insert the mounting bolts. Do not over-torque — the plastic housing can crack or distort.
7. Reconnect the hose and refill coolant: Reconnect the coolant hose and tighten the clamp. Refill with the correct coolant mixture and bleed the system according to the ISUZU procedure.
8. Run and verify: Start the engine, bring it to operating temperature, and check for leaks at the housing joint and hose connection. Confirm the temperature gauge stabilizes.

• Inspect the housing/cover joint at every coolant service or every 20,000–30,000 km — look for crusty residue or dampness.
• Replace gaskets whenever the housing is removed — gaskets are single-use compression seals.
• Flush coolant according to the manufacturer interval. Degraded coolant accelerates corrosion of the aluminum cover and degradation of the plastic housing.
• Replace the housing if the sealing surface is pitted, the outlet is deformed, or a crack is detected in the plastic housing.

• Standard packing: Neutral packaging / customer-branded packaging available.
• Package contents: 1 × Water Outlet Pipe / Thermostat Cover. Thermostat element is NOT included unless explicitly stated — confirm at inquiry.
• Set options: Housing/cover only (standard) / housing + thermostat + gasket kit (where available) — specify at inquiry.
• Suitable for: ISUZU NKR55 / NHR55 / 100P cooling-system repair shops, light commercial fleet maintenance departments, spare parts distributors, and export wholesalers.