Gear Case Gasket 8-97331631-2 8973316312 For ISUZU D-MAX TFR TFS MU-X UCS UCR Rodeo Colorado 4JK1 4JJ1 — OEM Verified 1.45mm Fiber-Elastomer Composite, 2-Notch

The Gear Case Gasket with OEM references 8-97331631-2 / 8973316312 is a precision sealing component engineered for ISUZU 4JK1 (2.5L) and 4JJ1 (3.0L) common-rail diesel engines. It is installed between the gear case cover (timing cover) and the gearbox/engine housing, containing lubricating oil within the timing and gear drive system while preventing external contamination from entering.

This gasket is defined by two critical identification features: a 1.45 mm nominal thickness and 2 identification notches. These are not cosmetic details — the thickness directly affects sealing compression and the alignment of the cover relative to the gear train. Using an incorrect thickness or a gasket without the correct notch count can cause oil seepage or inadequate clearance.

The construction is a fiber-elastomer composite: a dimensionally stable carrier layer combined with an integrally bonded elastomeric sealing layer. This design maintains compressive force across thermal cycling and vibration while resisting hot transmission oil. Many ISUZU genuine applications also specify a subcoat of liquid gasket (e.g., ThreeBond 1207B or equivalent) on specific joint surfaces before cover installation to ensure complete sealing integrity.

• Thickness Verified: 1.45 mm — confirmed by ProPartsDiesel ("thickness: 1.45mm, 2 notches") and Guangzhou Ryisuzu ("T=1.45").
• Notch Count Verified: 2 notches — confirmed by ProPartsDiesel and the Thai market listing ("2 ร่อง" / 2 grooves).
• Material Construction Verified: Fiber-elastomer composite — a dimensionally stable carrier layer with an integrally bonded elastomeric sealing layer, confirmed by technical description of ISUZU Genuine gear case gaskets.
• OE Cross-Reference Verified: Replaces 8973316312, 8-97331-631-2, 8973316311, 8-97331-631-1, 8-97331631-1, 8-98135954-0, 8-97328-867-2, 8-97328828-1.
• Vehicle Coverage Verified: Confirmed for D-MAX TFR/TFS (Thailand/India), D-MAX 8DH, MU-X UCS/UCR (LHD/RHD), KB Pick-up, and related Chevrolet Colorado applications.
• Engine & Equipment Coverage Verified: 4JK1, 4JJ1, 4JJ1-TCS diesel engines, plus Hitachi CX130B and JCB equipment applications.
• Weight Reference: Approximately 600 g (Thai market listing reference for the OEM part).

• Oil seepage at the gear case / timing cover joint: Visible wet oil film or drips at the interface between the cover and the main housing — the most direct sign of gasket failure.
• Oil accumulation on the undercarriage or bellhousing area: Oil migrating rearward from the front cover joint can mimic a rear main seal leak, making accurate diagnosis important.
• Low engine oil level without blue exhaust smoke: A timing cover leak reduces oil level without the telltale burning-oil smoke of piston ring or valve guide wear.
• Contamination ingress into the gear case: A compromised gasket allows dust and moisture into the timing/gear drive area, accelerating wear of gears, bearings, and synchronizers.
• Repeat leaks after a previous cover service: A common outcome of using an incorrect thickness, incorrect notch count, or low-quality aftermarket gasket with mismatched cutouts or inconsistent material.

• Thickness and notch count are the first checks: Confirm the original gasket is 1.45 mm with 2 notches. Do not substitute a gasket of different thickness or notch count, even if the bolt pattern appears similar.
• Related OE 8-98135954-0: This number is frequently cross-listed alongside 8-97331631-2. Confirm which reference is stamped on the original gasket or specified in the parts catalog for the exact model year.
• LHD vs. RHD: The MU-X application covers both LHD and RHD (UCS/UCR). The gasket itself is not handed, but confirming the chassis code ensures the correct engine variant and cover configuration.
• Liquid gasket requirement: ISUZU genuine procedure specifies a subcoat of ThreeBond 1207B (or equivalent) on specific joint surfaces. Using the gasket dry where sealant is specified can result in repeat leakage.
• Timing cover service: When replacing the timing chain, belt, or cover, industry practice recommends replacing the gear case gasket simultaneously to avoid repeat labor and leakage risk.

1. 1Confirm the original gasket spec first: Measure the removed gasket thickness (1.45 mm) and count the notches (2). Compare against the replacement before installation.
2. 2Clean the mating surfaces thoroughly: Remove all old gasket residue, sealant, and oil film from both the gear case cover and the housing face. Do not gouge or scratch the machined surfaces — microscopic imperfections are filled by the elastomeric layer only when the surface is clean.
3. 3Apply liquid gasket where specified: If the ISUZU procedure for the specific application requires it, apply a subcoat of ThreeBond 1207B (or equivalent) to the specified joint surfaces before positioning the gasket. Do not apply excessive sealant that could block oil passages.
4. 4Position the gasket dry or with specified sealant: Seat the gasket on the housing face, aligning all cutouts and bolt holes. Do not stretch or distort the gasket during positioning.
5. 5Install the cover and torque in sequence: Follow the workshop manual torque sequence and specification. Uneven or over-torqueing can crush the gasket unevenly, causing seepage paths.
6. 6Allow sealant cure before oil fill: If liquid gasket was used, observe the specified cure time before adding oil or starting the engine.
7. 7Check oil level and inspect for leaks: After running the engine to operating temperature and cooling down, re-check the oil level and inspect the gear case joint for any sign of weeping.

• Inspect the gear case joint at every engine oil change — look for oil film, drips, or accumulated dirt adhering to oil seepage.
• Replace the gasket whenever the timing cover is removed — gaskets are single-use compression seals and should not be reused.
• Use the correct oil specification for the 4JK1/4JJ1 and adhere to the recommended change interval; degraded oil accelerates gasket hardening.
• Address any seepage promptly — a slow leak can become a sudden failure, and oil starvation in the gear case is a catastrophic failure mode.

• Standard packing: Neutral carton with protective flat packaging to prevent creasing; bulk export pallet available.
• Package contents: 1 × Gear Case Gasket. Liquid gasket (ThreeBond 1207B or equivalent) and mounting hardware are not included.
• Set options: Single gasket / timing cover service kit (gasket + sealant) — specify at inquiry.
• Suitable for: ISUZU D-MAX / MU-X / Rodeo / Colorado engine repair shops, Hitachi / JCB equipment service providers, fleet maintenance departments, spare parts distributors, and export wholesalers serving Southeast Asia, Australia, the Middle East, Africa, and Latin America.
• Related parts available: Timing cover, timing chain/belt, front crank seal, oil pan gasket, and complete 4JK1 / 4JJ1 lower-engine gasket kits.