Powerful 1999 Jeep TJ Engine—Ready to Roll!

Jeep EngineIs your TJ’s legendary 4.0L getting tired? If you’re chasing misfires, low compression, or an oil-burning six, we’ve got a drop-in solution that brings your Wrangler back to trail-ready reliability.

The Engine at a Glance

  • Vehicle: 1999 Jeep Wrangler TJ

  • Engine: 4.0L Inline-6 (AMC 242)

  • Configuration: Includes timing cover (T/C), oil pan, and horizontal oil filter mount

  • Fitment: Designed for AMC 4.0/242 applications, 1999–2006 (Wrangler TJ and other platforms using the 4.0L)

  • Build Quality: Remanufactured to OE specs or better, with updated components where available

🔧 We can help verify fitment by VIN and casting details before you order.

Why the 4.0L Reman Makes Sense

The Jeep 4.0 is famous for its torque and durability—but age, overheating, and oil consumption take their toll. A remanufactured long block:

  • Replaces worn pistons, rings, bearings, and valvetrain components

  • Restores compression and oil control

  • Delivers smooth cold starts and consistent power under load

  • Saves time versus chasing multiple repairs on a high-mileage core

Why Choose Gearhead Engines

  • FREE Shipping (continental U.S.)

  • FREE 4-Year Warranty for real peace of mind

  • Built to OE specs or better with thorough machining and testing

  • Core return made easy—straightforward credit and we help with the logistics

  • Optional Premium Install Kit so your tech has the gaskets and ancillary parts needed for a clean swap

  • Friendly, knowledgeable support from real humans who know Jeeps

Common Signs It’s Time to Replace

  • Persistent oil consumption or blue smoke

  • Low compression across one or more cylinders

  • Knock/tick that survives proper oiling and top-end checks

  • Coolant in oil (head gasket/overheat history)

  • Repeated misfires (P0300–P0306) after coils, plugs, and injectors are ruled out

Installation Tips for a Trouble-Free Swap

  1. Cooling system refresh: radiator clean/replace as needed, new thermostat and hoses.

  2. Oil system: prime before first start; use the recommended oil weight.

  3. Fuel & spark: fresh plugs; inspect coils/injectors and replace tired components.

  4. Break-in: vary RPM, avoid long idles/heavy loads initially; follow the early oil-change interval.

  5. Baseline scan: clear codes and record trims after initial heat cycles.

Get a FREE Quote from a Jeep Engine Specialist

Have your VIN handy and we’ll confirm fitment, warranty coverage, and lead time—no pressure, just straight answers.

Speak with an expert and get a FREE quote today:
800-508-5999
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