Eliminate excessive oil consumption and restore factory compression with the Nissan Altima QR25DE Remanufactured Engine across heavy daily traffic. This 2.5L 4-Cylinder 16-Valve DOHC long block features the AU7 block casting engineered for front-wheel-drive configurations. Diamond plateau honed cylinders seat rings without delay. Technicians must prime the oil pump prior to startup to avoid bearing starvation.

Die-cast aluminum alloy forms the cylinder block stamped with the AU7 casting identifier, fitted with centrifugal cast iron cylinder liners. A micro-polished forged steel crankshaft spins within align-honed main bearing saddles below a 16-Valve DOHC aluminum cylinder head. Dry engine mass measures 220 lbs. Packaging dimensions span 36in length, 36in width, and 36in height, with the lower stamped steel oil pan holding 4.9 quarts of motor oil.

Key Features of Nissan QR25DE

Fleet repair centers buy Nissan Altima QR25DE remanufactured engine assemblies to restore worn passenger sedans to original emission compliance. This precision long block replaces tired powertrains in front-wheel-drive chassis configurations.

- Intake camshaft variable timing phaser optimizes valve overlap to produce strong low-end torque.
- Re-machined AU7 block casting maintains true cylinder roundness to stop oil burning issues.
- Forged steel crankshaft features micro-polished journals to preserve hydrodynamic bearing oil films under load.
- Centrifugal cast iron cylinder sleeves receive diamond plateau honing passes to seat replacement rings.
- Multi-layer steel cylinder head gasket withstands extreme combustion pressures without coolant jacket breach.
- Hardened valve seats prevent valve recession under continuous high exhaust temperature conditions.
- Dual overhead camshafts drive 16 valves through shimless buckets to minimize valvetrain friction.

Dyno Load Precision Machining Tolerances

Dynamometer load testing confirms 175HP at 6,000 RPM and 180 ft-lbs torque at 4,000 RPM on standard gasoline. Crankshaft main journal runout measures within 0.0003in TIR across induction-hardened bearing pins. Connecting rod oil clearances hold at 0.0013in to maintain hydrodynamic bearing lubrication during aggressive acceleration. Sump lubrication pressure sustains 60 PSI at 3,000 RPM with coolant stabilized at 195°F. Cylinder compression gauges verify 180 PSI across all four cylinders, confirming concentric valve seats and uniform piston ring end-gap fitment.

Vehicle Fitment Drivetrain Guide

Exact vehicle fitment encompasses 2005 to 2006 Nissan Altima and 2005 to 2006 Nissan X-Trail models equipped with the L4 2.5L 2488cc engine in front-wheel-drive configuration. Identification confirms block casting AU7 with a dedicated FWD bellhousing pattern. It mates with factory 4-Speed automatic and 5-Speed manual transaxles. This casting does not fit all-wheel-drive X-Trail chassis with 8H7 blocks, JA0 casting Rogue crossovers, or rear-wheel-drive Frontier pickups.

Installation Protocol Service Schedules

Electronic drive-by-wire throttle connections require clean contact surfaces during subframe mounting. Mechanics must inspect exhaust header pre-catalytic converters to prevent ceramic dust ingestion into fresh cylinders. Never drop this naturally aspirated factory block into high-boost turbo setups running over 8 PSI on stock cast pistons.

- Drain initial break-in engine oil and swap the spin-on filter after 500 operating miles.
- Inspect serpentine accessory drive belt tension and coolant level every 10,000 road miles.
- Change motor oil and filter every 3,000 miles using certified 5W-30 synthetic engine oil.

Warranty Terms Core Return Policy

Warranty coverage provides a 3-Year Unlimited-Mile replacement guarantee on internal lubricated engine mechanical components. Return your like-for-like core within 30 days using prepaid freight documentation to claim your core credit. The secure crate contains the remanufactured long block, complete timing assembly, oil pan, and shop installation guides.