Jeep 4.2L L6 Remanufactured Engine – 1987-1987

Description

Across grueling 10-hour public utility work shifts demanding continuous low-RPM winching and trailer hauling, diamond-plateau honed cylinders hold zero oil bypass inside the Jeep 4.2L L6 Remanufactured Engine for 1987 Wrangler YJ and Grand Wagoneer applications equipped with carbureted 258 cubic inch inline-six power plants.

Cast iron block metallurgy features deep cylinder walls line-honed to original main bore centerlines. A heavy nodular cast iron crankshaft spins inside micro-groove tri-metal bearings, driven by forged connecting rods and hypereutectic aluminum pistons. Cylinder decks are milled to an Ra 35 micro-inch finish. Bare block dry weight measures 445 lbs, taking 5 quarts of oil.

Key Features of Jeep 4.2L L6

Restoration shops buy Jeep 4.2L L6 remanufactured engine packages to return classic utility vehicles to factory pulling power. This inline-six design outputs exceptional off-idle rotational force for demanding field operations.

• 0.0016-inch rod bearing clearances provide sustained hydrodynamic oil boundaries under lugging conditions
• Multi-layer steel gaskets maintain cylinder head clamping force across fluctuating thermal states
• Induction-hardened exhaust valve seats accommodate unleaded commercial fuels without valve recession
• Precision ground camshaft profiles maximize low-RPM torque output from 1200 RPM through 2400 RPM
• Cast iron oil pump bodies housing steel gears provide steady pressure flow across all oil passages
• Computerized rotating balancing limits engine vibration to preserve motor mount life expectancy
• Jeep 4.2L L6 long block units align straight to original mechanical fuel pumps and manifolds
• Stellite-faced exhaust valves resist combustion burning under continuous heavy utility trailer hauling

Operational Compression Oil Pressure Specifications

Operating lubrication channels maintain 15 to 20 PSI hot idle and 45 to 60 PSI cruise oil pressure. Pressurized water passages stabilize operating coolant temperature between 180°F and 195°F through the cooling system. A 9.2:1 compression ratio outputs 112 horsepower at 3200 RPM and 210 lb-ft torque at 2000 RPM. Cranking compression yields 140 to 150 PSI across all six cylinders. Severe Vocational Fleet rating rejects 3800 BTU/min heat.

Crankshaft Flywheel Pilot Fitment Parameters

The aft crankshaft flange provides a 6-bolt flywheel pattern alongside a 1.050-inch pilot bushing aperture. The front snout measures 1.375 inches with a standard single woodruff keyway for mechanical fan hubs. Crankshaft thrust endplay registers between 0.004 and 0.007 inches, protecting the thrust bearing flange during clutch pedal depression.

Pre-Lubrication Directive Disqualified Operating Conditions

Engage the internal oil pump with an external drive shaft until lubricant flows from every pushrod cup. Run high-zinc SAE 10W-30 break-in oil for 500 initial miles. This engine is not engineered for multi-stage nitrous injection, excessive supercharging, continuous boat propulsion, or vehicle payloads exceeding original factory ratings.

• Check oil dipstick level and radiator coolant overflow tank each shift prior to operation
• Replace break-in lubricant and install a new spin-on filter after 500 initial miles
• Change crankcase engine oil and replace the oil filter every 250 hours or 3,000 miles

Commercial Warranty Protection Included Crate Components

This engine comes backed by a 3-Year / 100,000-Mile commercial warranty against manufacturing defects. The sealed transport container contains the remanufactured long block engine, high-flow oil pump, complete install gasket set, break-in guide instructions, and dyno quality control clearance papers.