Thermostat Cover 8-97355456-4 8973554560 For ISUZU D-MAX TFR TFS 2005 4JJ1TK 4JK1 2.5/3.0 DiTD — OEM-Grade Aluminum Die-Cast, Direct Fit Cooling Housing Cap

The Thermostat Cover with OEM references 8-97355456-4 / 8973554560 is a verified replacement for ISUZU D-MAX (TFR/TFS) pickups equipped with 4JJ1TK / 4JJ1-TC (3.0L) and 4JK1 (2.5L) common-rail diesel engines, particularly the 2005–2013 model years. This cover is the thermostat housing cap that seals the thermostat cavity and forms the closed cooling circuit with the cylinder head. Its function is to fix the thermostat in position, prevent coolant leakage, and allow the thermostat to regulate coolant flow as engine temperature changes.

The part is manufactured from aluminum die-cast construction, providing dimensional stability and corrosion resistance in the hot coolant environment. It is a brand-new component, not remanufactured, and is widely cross-referenced with 8981209450 in the aftermarket supply chain for the D-MAX 4JJ1/4JK1 application. Reference warranty is 6 months, with a supply capacity of 10,000 pcs/month from Chinese aftermarket factories.

• OEM Reference Verified: 8-97355456-4 / 8973554560 is confirmed across multiple independent aftermarket supplier listings as the thermostat cover/cap for ISUZU D-MAX 4JJ1 / 4JK1 engines.
• Cross-Reference Verified: 8981209450 is widely listed as an interchangeable or companion reference for the same D-MAX 4JJ1/4JK1 thermostat cover application.
• Function Verified: The thermostat cover fixes the thermostat, forms a closed cooling circuit, prevents coolant leakage, and enables temperature-regulated coolant flow.
• Engine Coverage Verified: Confirmed for 4JJ1 (3.0L) and 4JK1 (2.5L) engines in ISUZU D-MAX TFR/TFS pickups, including 2005-era and subsequent model years.
• Material Verified: Aluminum die-cast construction — consistent with the thermal and sealing requirements of a thermostat housing cover.
• Supply & Warranty Reference: MOQ 10 pcs, 10,000 pcs/month capacity, 15–20 day lead time, and 6-month warranty confirmed by Chinese factory supplier data.
• Related Component Identification: 8-97355-456-7 (water outlet pipe) and 8-98120-945-0 (alternate water outlet) are adjacent cooling-system components in the same ISUZU parts diagram — not interchangeable with 8-97355456-4.

• Coolant leak at the thermostat housing: Visible drips, dampness, or crusty residue (white/pink coolant crust) around the cover-to-housing joint — the most direct sign of a failed cover gasket or a warped/corroded cover sealing surface.
• Overheating or temperature fluctuation: A cover 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.
• Visible corrosion or pitting on the cover sealing surface: Aluminum covers can corrode at the coolant passage edges, preventing the gasket from sealing even when new.
• Cracked or deformed cover: Impact damage or over-torqueing of the mounting bolts can crack the aluminum casting, requiring replacement.
• Repeated coolant loss without an obvious external leak: A compromised cover joint can allow coolant to seep slowly, producing unexplained reservoir level drops.

• Component scope must be confirmed first: This is the thermostat cover (cap) — not the water outlet pipe (8-97355-456-7) and not the thermostat itself (8-97361-770-0 / 8-98017-027-2). Compare the original unit's shape (flat/domed cap vs. pipe with hose neck) before ordering.
• 8-97355456-4 vs. 8-97355-456-7: These are different part numbers with different functions. The former is the thermostat cover; the latter is the water outlet pipe. Do not interchange them.
• 8981209450 association: This reference is frequently listed alongside 8973554560 as a companion or interchangeable thermostat cover for the D-MAX 4JJ1/4JK1. Confirm which reference is stamped on the original cover or specified in the parts catalog for the exact model year.
• 2005 4JJ1TK: The user-specified “4JJ1TK” is an early 4JJ1 variant. The 4JJ1 family (including 4JJ1-TC, 4JJ1-TCX) shares the same thermostat housing architecture in the D-MAX TFR/TFS platform, but VIN confirmation is recommended for transitional model years.
• Gasket not included: The thermostat housing gasket (8-97212-537-1 or 8-98114-587-0) is a separate component. Confirm whether the cover is supplied with a gasket or requires separate purchase.

1. Confirm the required component first: Verify that the original unit is the thermostat cover (8-97355456-4), not the water outlet pipe (8-97355-456-7) or the thermostat itself. Compare the physical shape and port configuration.
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 cover: Unbolt the cover from the thermostat housing. Note the orientation and any hose connection. Do not pry against the aluminum sealing surface.
4. Clean the mating surface: Remove all old gasket residue and corrosion from the housing face and the cover sealing surface. A clean, flat surface is essential for a leak-free seal.
5. Inspect the thermostat: With the cover removed, check the thermostat for correct operation. Replace if stuck open or closed.
6. Install the new cover with a new gasket: Seat a new gasket (8-97212-537-1 or 8-98114-587-0 — confirm inclusion) on the housing, position the cover, and insert the mounting bolts.
7. Torque in sequence: Tighten the cover 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 hoses and refill coolant: Reconnect any hose to the cover neck (where applicable). Refill with the correct coolant mixture and bleed the system according to the ISUZU procedure.
9. Run and verify: Start the engine, bring it to operating temperature, and check for leaks at the cover joint. Confirm the temperature gauge stabilizes and the heater blows hot.

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

• Standard packing: Neutral box / color box / customer-branded packaging available.
• Package contents: 1 × Thermostat Cover. Gasket, thermostat, and mounting bolts are not included unless explicitly stated.
• Set options: Cover only / cover + gasket set — specify at inquiry.
• Suitable for: ISUZU D-MAX cooling-system repair shops, pickup fleet maintenance departments, spare parts distributors, and export wholesalers serving Southeast Asia, the Middle East, Africa, and Latin America.
• Related parts available: Thermostat (8-97361-770-0 / 8-98017-027-2), thermostat housing gasket (8-97212-537-1 / 8-98114-587-0), water outlet pipe (8-97355-456-7), and complete 4JJ1 / 4JK1 cooling-system kits.