The Isuzu 4JG2 is a 2,999 cc, inline‑four turbo‑diesel engine produced between 1993 and 2002. It features a single overhead camshaft (SOHC), indirect injection, and a fixed — geometry turbocharger, delivering 88 kW (120 PS) and 285 Nm of torque for heavy — duty commercial and 4x4 applications. Its robust cast iron construction provides exceptional durability for off — road and load — carrying use.
Fitted primarily to the Isuzu Trooper (UBS) and Bighorn, the 4JG2 was engine…
Production years 1993–2002 meet Euro 2 standards for applicable markets .
The Isuzu 4JG2 is a 2,999 cc inline‑four turbo‑diesel engineered for SUVs and light commercial vehicles (1993-2002). It combines a robust SOHC design with indirect injection and a fixed-geometry turbocharger to deliver strong, reliable pulling power. Designed to meet Euro 2 emissions standards, it prioritizes rugged durability over refinement.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,999 cc | |
Fuel type | Diesel | |
Configuration | Inline‑4, SOHC, 8‑valve | |
Aspiration | Turbocharged | |
Bore × stroke | 98.5 mm × 98.5 mm | |
Power output | 88 kW (120 PS) | |
Torque | 285 Nm @ 2,000 rpm | |
Fuel system | Mechanical indirect injection (Denso pump) | |
Emissions standard | Euro 2 | |
Compression ratio | 20.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | Fixed-geometry turbo (IHI) | |
Timing system | Gear-driven camshaft | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 245 kg |
The Isuzu 4JG2 was used in Isuzu's UBS platform with longitudinal mounting. This engine received a significant cylinder head revision in 1998 to address cracking issues, creating a clear compatibility break for head gasket and head replacements. All adaptations are documented in OEM technical bulletins.
Engine Finders UK Ltd, which operates EngineCode.uk, can pass your enquiry to engine suppliers in the UK. The service is for vehicles in the United Kingdom, with UK delivery or fitting. This is a commercially connected service, and sending an enquiry does not confirm diagnosis or compatibility.
Diagnostic reminder: If a technician has recommended replacing the engine, you can send an enquiry to engine suppliers in the UK. Confirm the diagnosis first: an engine-code record does not diagnose a fault.
Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The 4JG2 is fundamentally robust, thanks to its gear-driven camshaft and simple indirect injection. Its main weakness is the cylinder head in pre-1998 models, which can crack if the engine overheats. With meticulous cooling system maintenance and using the post-1998 head if rebuilding, these engines are renowned for exceeding 400,000 km.
The most critical issue is cylinder head cracking in early models. Other common problems include injection pump diaphragm failure causing fuel to leak into the oil, glow plug system failures for cold starts, and age-related coolant leaks. These are well-documented in Isuzu service literature.
The 4JG2 was primarily used in the second-generation Isuzu Trooper/Bighorn (UBS) from 1993 to 2002. It was also used by Opel in the Monterey and by Honda in the Horizon during the 1990s, as part of OEM partnerships.
Significant power gains are possible by modifying the mechanical injection pump to deliver more fuel and installing a larger turbocharger. However, the indirect injection system and older engine design limit its ultimate potential compared to modern direct injection diesels. Supporting modifications like an intercooler are essential.
Moderate for its size and era. In a Trooper, expect real-world fuel economy of approximately 11.5 L/100km (25 mpg UK) on the highway and 14.5 L/100km (19 mpg UK) in the city. Its weight, aerodynamic profile, and indirect injection system contribute to its thirst.
No. The 4JG2 is a non-interference (free-wheeling) engine. This means if the timing gears were to somehow fail (which is extremely rare), the pistons will not contact the valves, preventing catastrophic internal damage. The engine will simply stop running.
Isuzu specified API CF-4 or CG-4 grade diesel engine oil, typically in 15W-40 viscosity. Modern equivalents meeting ACEA B3/B4 specifications in the same viscosity are suitable and offer excellent protection for the turbocharger and high-pressure injection system.
Comprehensive technical documentation and regulatory references
EngineCode.uk is operated by Engine Finders UK Ltd. It provides engine-reference information and an optional commercial enquiry service. It is not an official manufacturer website. Check the record's sources and confirm vehicle-specific details before relying on it for parts, repairs or replacement.
Our editorial standard prioritises relevant manufacturer documentation and official regulatory sources. The sources and verification status for a record should be checked alongside the data.
A statement is not verified merely because a source is listed. Where supporting evidence is missing or conflicting, the record should identify that limitation. Please report unsupported or inconsistent information.
Transparency in gaps
A missing or unverified value does not mean the manufacturer has withheld it. We distinguish information not yet verified, information not available to us, and information explicitly not disclosed by the source.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Records are subject to review and correction. Source links, dates and verification notes should be read with the technical information. Our Editorial and Sourcing Policy explains our standards and review process.
Found an error or missing source? Report a problem with this page. Include the field or statement concerned and a supporting source if available. You can also email corrections@enginecode.uk.
Copyright and permissions
Images and other material may be protected by copyright. Attribution does not by itself grant permission to reuse material. If you believe material on this site infringes your rights, contact copyrights@enginecode.uk with the page URL and details of your claim. We will review the material and take appropriate action.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
Our Privacy Policy explains how Engine Finders UK Ltd uses information from visits, vehicle lookups, enquiries and messages. Our Cookie Policy explains cookies and similar technologies and how to change your choices.
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
Ownership and commercial services
EngineCode.uk is owned and operated by Engine Finders UK Ltd. Alongside our reference content, we offer an optional replacement-engine enquiry service through Engine Finders and may identify relevant services provided by businesses connected with us. These commercial connections are disclosed. Using an enquiry service is not required to read our reference content.
Engine Finders UK Ltd operates this website. Our optional enquiry service has a commercial purpose. Our Ownership and Commercial Disclosure explains the relationship between the reference website and that service. Participating suppliers pay a fee or subscription to participate on the network and receive quote requests.
Use this record as a starting point for identification. Specifications and vehicle applications may contain errors or omissions. Confirm the exact engine variant and compatibility using vehicle-specific documentation and a qualified supplier or technician.
All external links open in new tabs. Please verify current availability of resources.