Featuring an exact 2498cc displacement, this Subaru Outback FB25B 2.5L Remanufactured Engine eliminates excessive oil consumption across boxer engine platforms. Production technicians line-hone split aluminum crankcase castings FB25 and H25 to secure crankshaft centerline trueness. This 2.5L 4-Cylinder 16-Valve DOHC H4 boxer powerplant requires pre-priming oil galleries prior to initial ignition fire to protect dual overhead camshaft journals.

Die-cast aluminum semi-closed split crankcase casting FB25 houses cast iron cylinder liners and a forged steel crankshaft micro-polished to 0.0003in runout. Aluminum cylinder head castings AB25 RH and AB25 LH feature wide rectangle intake ports, sixteen valves, and intake-only variable valve timing. Hypereutectic aluminum pistons pair with low-tension moly rings. Crated long block weight registers 250 lbs with crated envelope dimensions of 38in length by 38in width by 38in height and holds 5.1 quarts oil.

Key Features of Subaru FB25B

All-wheel-drive service facilities buy Subaru FB25B remanufactured engine assemblies to restore quiet boxer engine operation and stop oil consumption. Technicians install this remanufactured 2.5L long block replacement to cure timing chain chatter.

- Split crankcase casting FB25 receives precision CNC deck resurfacing to secure multi-layer steel cylinder head gaskets.
- Asymmetrical connecting rod big ends receive align-honing to set rod bearing oil clearance at 0.0012in.
- Micro-polished crankshaft journals hold 0.0003in TIR to eliminate bearing friction under continuous highway cruising loads.
- Cylinder head castings AB25 RH and LH receive three-angle valve seat cutting to hold 0.001in valve runout.
- Plateau-honed cylinder sleeves seat replacement piston rings within 500 miles to eliminate oil consumption.
- Pre-timed dual silent timing chains maintain precise camshaft synchronization across both horizontal cylinder banks.
- Multi-layer steel head gaskets come pre-installed with torque-to-yield cylinder head bolts torqued to factory specifications.

Dyno Load Precision Machining Tolerances

Dynamometer testing verifies 175 HP at 5,800 RPM alongside 174 ft-lbs shaft torque at 4,000 RPM under continuous testing resistance. Machine shop craftsmen maintain crankshaft main journal alignment within 0.0003in TIR while rod bearing clearances measure 0.0012in. Computerized horizontal bore honing holds piston-to-bore clearance at 0.0011in to eliminate cold piston slap. Operating engine oil pressure sustains 55 PSI at 3,000 RPM with engine coolant stabilized at 195°F. Mechanical cylinder pressure gauges confirm balanced compression between 185 PSI and 190 PSI across all four boxer cylinders.

Vehicle Fitment Drivetrain Guide

This remanufactured engine fits 2015 to 2019 Subaru Legacy and 2015 to 2019 Subaru Outback models equipped with the 2.5L 2498cc H4 MPI engine, wide rectangle intake ports, and AB25 cylinder heads. It pairs with Lineartronic CVT all-wheel-drive transmissions. This long block does not fit earlier 2013 to 2014 BE25 head engines, direct-injected 2020 and newer FB25D platforms, 2.0L FA20 turbo engines, or older EJ25 boxer platforms.

Installation Protocol Service Requirements

Inspect multipoint intake manifold gaskets and clean transmission bellhousing dowel pins before dropping the long block into the engine cradle. Never operate this naturally aspirated boxer motor in high-boost aftermarket turbo installations or off-road buggies lacking secondary oil filtration. Mechanics must burp boxer cooling passages to eliminate trapped air pockets.

- Pressure-prime the oil system through the front port before initial cranking to coat camshaft lobes and chain tensioners.
- Drain the break-in motor oil and install a genuine black Subaru oil filter at 500 miles.
- Inspect variable valve timing solenoid advance angles and recheck coolant levels at 3,000 miles.

Warranty Terms Core Return Policy

Our standard 3-Year Unlimited-Mile warranty safeguards internal long block components and machine shop labor against defects. We arrange free prepaid freight collection for your old engine core within a 30-day window. The crated shipment contains the assembled long block core, pre-installed timing components, oil pan, and valve covers.