4HG1-OLD 4HF1 4HG1T 8-97144985-1 8-97144986-0 8-97144985-0 8-97144984-0

ISUZU 4HG1-OLD 4HF1 4HG1T 8-97144985-1 8-97144986-0 8-97144985-0 8-97144984-0 

1. Quick Notice

Confirm your engine code (4HG1, 4HG1T, 4HF1, 4HJ1) and gasket thickness before ordering. These OEM numbers correspond to different components — identify your specific requirement. Professional installation required.

2. Description

Isuzu 4HG1 is a 4.6L four-cylinder inline diesel engine with 105mm bore × 125mm stroke, 17.5:1 compression ratio, turbocharged. Features overhead camshaft (OHC) and direct injection-28. The OEM number 8-97144-986-0 is a full cylinder gasket set (overhaul gasket kit), including head gasket, intake/exhaust manifold gaskets, oil pan gasket, valve seals, and more-10. Numbers 8-97144985-1, 8-97144985-0, and 8-97144984-0 are individual cylinder head gaskets for different engine variants. Each ensures airtight sealing between engine block and cylinder head-18. Fits Isuzu NPR, NQR, NKR, and ELF trucks (1992–2003), 4HG1 naturally aspirated and 4HG1T turbo versions-27. Also fits 4HF1, 4HJ1 engines. Applications include commercial trucks, buses, and excavators. Common failure symptoms include external coolant seepage, white exhaust smoke, milky oil, compression loss, and overheating.

3. Parameters Table

4. Custom Content

Thickness Selection: The 4HG1 head gasket comes in multiple thickness grades. Determine the correct thickness by measuring piston protrusion above the block deck and following the Isuzu workshop manual. The correct gasket is sometimes identified by notch codes on the gasket tab or by a letter stamp on the front left corner of the cylinder block. Incorrect thickness may cause piston-to-valve contact or low compression.

Full Gasket Set Contents (8-97144-986-0): Includes cylinder head gasket, intake and exhaust manifold gaskets, oil pan gasket, valve cover gasket, rocker arm cover gasket, valve stem seals, front and rear oil seals, and turbocharger gaskets-10.

Surface Preparation: Both cylinder head and block surfaces must be thoroughly cleaned with a plastic scraper. Do not use abrasive discs or wire brushes.

No Additional Sealant: Install individual head gaskets dry. However, for the full gasket set, some applications require liquid gasket at specific points of the cylinder head — refer to the service manual. Always replace head bolts with new units.

5. FAQ (One by One Question and Answer)

Q1: What is the difference between 8-97144-986-0 and 8-97144985-0?
A1: 8-97144-986-0 is a complete overhaul gasket set (multiple components). 8-97144985-0 is an individual cylinder head gasket only.

Q2: Which Isuzu trucks use the 4HG1 engine?
A2: Isuzu NPR, NQR, NKR, and ELF trucks (1992–2003) with 4HG1 naturally aspirated (130 PS) or 4HG1T turbocharged (140 PS)-27.

Q3: What are common head gasket failure symptoms on a 4HG1?
A3: External coolant seepage at head joint, persistent overheating, white exhaust smoke, milky oil, and exhaust bubbles in the radiator.

Q4: Is this gasket suitable for turbocharged 4HG1T engines?
A4: Yes. 8-97144-986-0 is specifically labeled for 4HG1TC-10. For individual head gaskets, verify with your original part number.

Q5: What is the tightening torque for cylinder head bolts?
A5: Cylinder head bolts require specific torque and angle. Using several passes, tighten all bolts gradually according to the specified sequence in the Isuzu workshop manual until reaching correct torque specification. Use new torque-to-yield (TTY) bolts.

Q6: Do I need new cylinder head bolts?
A6: Yes. Always replace cylinder head bolts with new units. Reused bolts have permanent stretch and may not achieve correct clamp load.

Q7: Does this kit include valve seals?
A7: The full gasket set (8-97144-986-0) includes valve stem seals as listed. Individual head gaskets do not include valve seals.

Q8: What vehicles use the 4HF1 engine?
A8: The 4HF1 engine is a 4.3L turbocharged version used in Isuzu NPR trucks and various medium-duty commercial applications.

Q9: What is the engine oil capacity for the 4HG1?
A9: Approximately 10.5 liters. API CF-4 or higher, SAE 15W-40 recommended..

Q10: Is sealant required for head gasket installation?
A10: Individual MLS head gaskets seal without additional sealant. For the full gasket set, apply liquid gasket only to the specified points as indicated in the Isuzu service manual. Do not apply sealant to the gasket itself unless specified.