4.0L 242 cui 6-cyl. "High Output" Engine Parts for Jeep Wrangler YJ
Engine Parts & Rebuild Kits for Jeep Wrangler YJ 4.0L High-Output: Pistons, Bearings, gaskets & More.
Restore the legendary, uncompromised power of your inline-six engine. We offer a comprehensive catalog for the 4.0L HO block – from high-precision pistons and bearing kits for the rotating assembly to premium aluminum valve covers and timing chain sets.
- Rotating Assembly: Standard & oversized pistons and premium rod bearings by Sealed Power and Enginetech.
- Valvetrain Spares: Enginetech hydraulic lifters, pushrods, and factory-style rocker arm pivot bridge sets by Crown.
- Timing Components: Heavy-duty timing chain kits by Enginetech & Sealed Power, camshaft gears, and retainers.
- Airtight Sealing: Master engine gasket sets (upper & lower), head gaskets, and premium aluminum valve covers by Crown.
- Oil System & Hardware: High-volume oil pumps, Dorman & Crown oil pans, harmonic balancers, and rod bolts.
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The Benchmark for Trail Torque: Overhauling Your Wrangler YJ 4.0L HO Powerplant.
The multi-point fuel-injected 4.0L inline-six High-Output engine introduced superior drivability and power to the Jeep Wrangler YJ starting in 1991. Famous for its low-end torque, this cast-iron icon can effortlessly handle extreme mileage. However, brutal off-road use, heavy loading, and high under-hood temperatures eventually take their toll. Cracked factory exhaust manifolds, noisy lifters, or leaky oil pan and valve cover gaskets are typical challenges that every YJ owner faces over time. Our specialized online inventory features professional-grade hardware to restore factory compression, structural integrity, and oil tightness back to your six-cylinder block.
Premium US Off-Road Engine Engineering: Enginetech, Sealed Power, and Crown.
For internal mechanical restorations, we rely strictly on the industry-leading standards of Enginetech and Sealed Power. We stock high-durability pistons available in standard and oversizes, matching piston rings, high-precision rod bearings, and camshaft bearings. Overhaul your valvetrain seamlessly with replacement hydraulic lifters, pushrods, and complete rocker arm bridge kits from Crown Automotive. Address exhaust leaks permanently with our heavy-duty exhaust manifolds from Crown, available individually or as a complete package paired with manifold gaskets and Dorman header bolts.Keep your engine timing perfectly synced with high-tensile timing chain kits, camshaft sprockets, and matching timing cover gaskets. Restore your lubrication circuit with high-volume Crown oil pumps, replacement oil pans from Dorman or Crown, and oil pan seals. Ensure smooth crankshaft rotation under heavy winch loads with a replacement harmonic balancer. For the ultimate visual and leak-free upgrade, we highly recommend swapping out the warp-prone factory plastic cover for a rigid Crown aluminum valve cover complete with a high-durability gasket. Our comprehensive range is finalized by target components like master engine gasket sets (upper & lower), cylinder head gaskets, valve stem seals, and original rod bolts or nuts from Crown and Mopar.