Description

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 belongs to one of the most respected engine platforms ever produced for Jeep vehicles. The 4.0-liter inline six-cylinder engine is widely known for its durability, strong torque output, and ability to handle demanding off-road conditions.

Originally developed by American Motors and later used by Jeep under Chrysler ownership, the 4.0L inline six engine became a staple powerplant in many Jeep vehicles for decades. Its simple design, strong internal components, and excellent low-end torque make it ideal for both everyday driving and off-road applications.

Over time, engines experience wear from mileage, heat cycles, and continuous use. Installing a remanufactured replacement engine allows owners to restore the vehicle’s performance and extend its lifespan.

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 provides a dependable solution for restoring the reliability and performance Jeep vehicles are known for.

Vehicles This Engine Fits

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 is designed for Jeep vehicles originally equipped with the 4.0-liter inline six-cylinder engine.

Typical compatible vehicles include:

• Jeep Cherokee (XJ)
• Jeep Comanche (MJ)
• early Jeep Wrangler models equipped with the 4.0L engine

These vehicles rely on the 4.0L inline six engine to deliver dependable torque and reliable performance across both on-road and off-road driving conditions.

Because engine compatibility depends on engine codes and VIN numbers, verifying the correct engine configuration before installation is important.

Build Quality and Engineering

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 is rebuilt through a detailed remanufacturing process designed to restore durability and performance.

During rebuilding, the engine is completely disassembled so every internal component can be inspected. Components showing wear or damage are replaced or restored to meet proper operating tolerances.

Key engine components inspected during rebuilding include:

• engine block
• crankshaft
• pistons and piston rings
• camshaft
• cylinder head
• bearings and seals

Precision machining restores important surfaces and ensures proper alignment of internal components. These processes help maintain proper compression, lubrication flow, and combustion efficiency.

The Jeep 4.0L inline six engine architecture is widely recognized for its strong block design and ability to perform reliably under demanding conditions.

Why This Engine Is a Reliable Choice

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 remains a popular replacement option because the Jeep 4.0 engine has a long reputation for durability and reliability.

Many Jeep vehicles equipped with this engine continue operating for high mileage when properly maintained.

Vehicle owners often choose remanufactured engines because they offer several advantages:

• restored engine performance
• compatibility with original vehicle systems
• dependable torque output
• reduced uncertainty compared to used engines

Replacing the engine with a professionally rebuilt unit allows Jeep owners to continue enjoying their vehicle for many additional years.

Who This Engine Is Designed For

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 is designed for buyers who require a dependable replacement engine for compatible Jeep vehicles.

Typical buyers include:

• Jeep Cherokee owners restoring vehicles
• off-road enthusiasts replacing worn engines
• automotive repair facilities performing engine replacements
• restoration specialists working on classic Jeep vehicles
• technicians specializing in Jeep engines

This engine is especially suitable for vehicles that remain structurally sound but require a replacement engine to restore reliable operation.

Engine Specifications

The Jeep 4.0L L6 Remanufactured Engine – 1987-1990 is a 4.0-liter inline six-cylinder engine developed for reliable torque output and durable long-term performance.

Key specifications include:

• Engine Type: Gasoline inline six-cylinder
• Displacement: 4.0 liters
• Cylinder Configuration: Inline 6 (L6)
• Fuel System: Electronic fuel injection (depending on model)
• Application: Jeep trucks and SUVs

The engine integrates with factory drivetrain components including the transmission, fuel system, and engine control components.

Because it is designed as a direct replacement engine, it connects with the original drivetrain systems used in compatible vehicles.

Ordering and Support

Ordering the Jeep 4.0L L6 Remanufactured Engine – 1987-1990 provides a dependable solution for vehicles experiencing engine failure or severe wear.

Before purchasing a replacement engine, it is recommended to confirm:

• vehicle VIN number
• engine code compatibility
• model year compatibility
• drivetrain configuration

Professional engine suppliers often assist customers in verifying the correct engine configuration before purchase to ensure proper installation.

With proper installation and routine maintenance, a remanufactured engine can provide dependable performance for many years.

Frequently Asked Questions

What vehicles use the Jeep 4.0L engine?

The Jeep 4.0L inline six engine was commonly used in Jeep Cherokee (XJ), Comanche (MJ), and several early Jeep Wrangler models.

Is the Jeep 4.0 engine reliable?

Yes. The Jeep 4.0L inline six is widely considered one of the most reliable Jeep engines ever produced due to its durable design and strong torque output.

What does remanufactured mean for an engine?

A remanufactured engine is completely disassembled, inspected, and rebuilt using restored or replacement components to restore reliable operation.

How long does a remanufactured Jeep 4.0 engine last?

With proper installation and maintenance, a remanufactured Jeep 4.0 engine can provide many years of dependable performance.

How do I confirm this engine fits my Jeep?

Compatibility should be verified using the vehicle VIN number, engine code, and model year before installation.

1987-1990 Jeep 4.0L L6. Block Cast #535, 665. VIN Code M.

Engine fitment can be verified with the notes and ‘Vehicle Fitment’ tab above, or with the casting numbers under ‘Additional Information’ (if applicable).

Every engine we sell is fully remanufactured to meet or exceed OEM specifications:

• Deep Clean – To start the remanufacturing process, every engine is fully disassembled and hot tanked (cast iron) or thermally cleaned (aluminum)
• Inspection – Magnaflux testing uses magnetic particles to inspect metal, checking for microscopic cracks and fissures that will cause long-term failure. All parts are visually inspected as well.
• Machining and New Parts – Deck surfaces are CNC machined and new parts are added. New parts inlcude bearings, pistons, rings, lifters, oil pump, gaskets, Viton™ valve seals, freeze plugs, galley plugs and either a new timing chain (with new tensioners) or a new timing belt (with new tensioner). If an engine has a timing-driven water pump, a new pump is installed.
• SIM Testing – Each engine is SIM tested after reassembly, with the cooling and oil systems being fully pressurized and the crank being spun at high RPM to verify compression and build quality.

Because of our rigorous remanufacturing process, we can offer the industry’s best warranties. Each engine comes with up to 7 years and 1 million miles of warranty, which can be upgraded to include Pure Care™ no-fault protection. No other engine manufacturer comes close.