Thermostat Housing 8-94310491-3 8943104913 For ISUZU 6BD1 6BG1 & Hitachi EX200-1 EX200-3 Excavator — High-Strength Aluminum Alloy, Polished Finish, Direct Fit

The Thermostat Housing with OEM references 8-94310491-3 / 8943104913 is a verified replacement cooling-system component for ISUZU 6BD1 and 6BG1 diesel engines, as well as Hitachi EX200-1, EX200-3, and related excavator models. This housing is the structural seat and enclosure for the engine thermostat — it holds the thermostat securely in position, forms the sealed coolant cavity against the cylinder head, and provides the mounting interface for the upper radiator hose connection.

• Engine Coverage Verified: Primary confirmed application is ISUZU 6BD1 (and 6BG1), confirmed across Ecer, DieselEngineSpare, FridayParts, and oilcooler-cover.com. 4BD1 appears only in broad supplier parts-catalog listings, not as a confirmed primary application for this specific housing.
• Equipment Coverage Verified: Confirmed for Hitachi EX200-1, EX200, EX200-3, and a wide range of additional Hitachi equipment including EX100-5, EX120-5, EX130H-5, EX135UR, EX140US-5, EX150LC-5, CP215, EG40R, HX220B, JD120, LX70-3, LX80-5, RT205, SR-P600 — confirmed by FridayParts application data.
• Material Verified: High-strength aluminum alloy — confirmed by DieselEngineSpare (English and Vietnamese listings) and oilcooler-cover.com (Arabic listing: "المواد:الألومنيوم" / material: aluminum).
• Weight Verified: 0.2 kg — confirmed by oilcooler-cover.com listing for 8943104913.
• Finish Verified: Polished ("ملمع" / polished) — confirmed by oilcooler-cover.com.
• Cross-Reference: 8943396272 is listed alongside 8943104913 by AntBuildz as an associated reference.

• Coolant leak at the thermostat housing joint: Visible drips, dampness, or crusty residue (white/pink coolant crust) around the housing-to-cylinder-head interface — the most direct sign of a failed gasket or a warped/corroded housing sealing surface.
• 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 in excavator or truck applications.
• Coolant residue on the engine block or under the machine: Dried coolant around the thermostat area indicates a slow weep that should be addressed before it becomes a sudden failure.
• Visible corrosion or pitting on the housing sealing surface: Aluminum housings can corrode at the coolant passage edges, preventing the gasket from sealing even when new.
• Cracked or deformed housing: Impact damage or over-torqueing of the mounting bolts can crack the aluminum casting, requiring replacement.
• Thermostat not seating properly: A distorted housing cavity can prevent the thermostat from sealing, causing continuous coolant bypass and extended warm-up times.

• Engine is 6BD1, not 4BD1 — this is the critical selection risk: This housing is confirmed by multiple independent catalogs as a 6BD1 / 6BG1 component. The query references 4BD1, which appears only in broad supplier parts lists, not as a confirmed primary application. The 4BD1 and 6BD1 engines have different cylinder counts, bore dimensions, and cooling-system layouts. A thermostat housing designed for the 6BD1 may not have the correct mounting hole spacing, coolant port alignment, or thermostat cavity depth for a 4BD1. Physically compare the replacement against the original 4BD1 housing before ordering.
• Verify the engine code first: If the vehicle or equipment is confirmed to be 6BD1 or 6BG1, this housing is the correct reference. If the engine is 4BD1, verify the original housing's part number and physical dimensions against a known 4BD1-specific thermostat housing before committing to this part.
• Equipment coverage is extensive but model-year-dependent: The Hitachi application list is broad, but the equipment serial number should be provided for final confirmation, as some variants may use different housing configurations.
• Gasket is not included: The thermostat housing gasket is a separate component. Always use a new gasket when installing the housing. Confirm gasket inclusion at inquiry.

1. Confirm the engine code and housing fitment first: Verify that the original engine is 6BD1 or 6BG1 (or physically confirm that the housing mounting pattern matches the 4BD1 application). Compare the replacement's mounting hole spacing, coolant port locations, and thermostat cavity depth against 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: Disconnect the radiator hose. Unbolt the housing from the cylinder head or thermostat seat. Note the orientation of the thermostat and any bypass ports.
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.
6. Install the new housing with a new gasket: Seat a new gasket on the cylinder head, position the 8-94310491-3 housing, and insert the mounting bolts.
7. Torque in sequence: Tighten the housing bolts evenly in a cross pattern to the workshop manual specification. Do not over-torque aluminum castings — excessive torque distorts the sealing surface and causes leaks.
8. Reconnect the hose and refill coolant: Reconnect the upper radiator hose. Refill with the correct coolant mixture and bleed the system according to the ISUZU or Hitachi procedure.
9. Run and verify: Start the engine, bring it to operating temperature, and check for leaks at the housing joint. Confirm the temperature gauge stabilizes.

• Inspect the housing joint at every coolant service or every 500 hours (for equipment) / every 20,000–30,000 km (for trucks) — look for crusty residue or dampness.
• Replace the gasket whenever the housing is removed — gaskets are single-use compression seals.
• Flush coolant according to the manufacturer interval. Degraded coolant accelerates aluminum corrosion.
• Replace the housing if the sealing surface is pitted or warped — resurfacing an aluminum housing is not recommended for this application.

• Standard packing: Neutral carton or wooden box; customer-branded packaging available.
• Package contents: 1 * Thermostat Housing. Gasket, thermostat, and mounting bolts are not included unless explicitly stated.
• Set options: Housing only / housing + gasket set — specify at inquiry.
• Suitable for: ISUZU 6BD1 / 6BG1 truck and engine repair shops, Hitachi excavator service providers, construction equipment maintenance departments, spare parts distributors, and export wholesalers serving Southeast Asia, the Middle East, Africa, and Latin America.
• Related parts available: Thermostat, thermostat housing gasket, upper radiator hose, water pump, and complete 6BD1 / 6BG1 cooling-system kits.