Subaru 2.5 Engine for Sale | OEM Used Subaru 2.5 Liter Horizontally-Opposed
$1,600.00
At a Glance
- Condition: OEM used, compression and leak-down tested all 4 cylinders
- Availability: In stock, Subaru 2.5L boxer engine available across the broader 2.5L family
- Shipping: Free shipping to all 50 states via heavy freight, 7 to 14 business days
- Engine family verified as Subaru 2.5L boxer (EJ25 family covering NA EJ251 / EJ252 / EJ253 / EJ254 / EJ255 / EJ257 variants)
- Year and variant confirmed (Phase I 1996-1998 / Phase II SOHC 1999-2010 / DOHC turbo variants 2002 plus / Phase III refinements)
- Application confirmed (Impreza, Legacy, Outback, Forester, Baja, WRX Turbo, STI)
- Horsepower rating documented (165-310 HP across family variants)
- Compression and leak-down tested all 4 cylinders (horizontally-opposed boxer)
- Both cylinder heads condition documented (boxer-4 with two heads)
- Head gasket condition assessed (CRITICAL Subaru 2.5L family concern)
- Timing belt condition assessed
- 15 day replacement warranty on internal defects
Description
About the Subaru 2.5L Boxer Engine Family
Looking for a replacement Subaru 2.5 engine? Part Nests stocks OEM used Subaru 2.5L horizontally-opposed boxer engines across the broader Subaru 2.5L engine family. The Subaru 2.5L boxer engine family represents Subaru’s mainstream displacement for passenger car, SUV, and performance applications across more than two decades of production. The 2.5L boxer family encompasses multiple variants and phases: the original EJ25 introduced in 1996 (Phase I), the revised EJ25 Phase II 1999-2010 with SOHC heads on most NA variants, the DOHC turbo variants EJ255 (WRX Turbo) and EJ257 (STI Turbo), and the refined Phase III variants. The 2.5L displacement is Subaru’s mainstream engine option used across Impreza, Legacy, Outback, Forester, Baja, WRX Turbo, and STI applications.
Engine Family Overview: Subaru 2.5L Boxer Architecture
- Displacement: 2.5 liters (2,457 cc)
- Configuration: Horizontally-opposed boxer-4 (180-degree opposed cylinders – Subaru signature design)
- Bore x Stroke: 99.5 mm x 79 mm (consistent across the family)
- Architectural variants: SOHC (most NA), DOHC (turbo variants), DOHC AVCS (later variants)
- Block: Aluminum (with cast iron cylinder liners)
- Fuel System: Port fuel injection (NOT direct injection in EJ family; the modern FA family introduced direct injection)
- Timing belt driven (timing belt service every 105,000 miles is critical)
- Production span: 1996-2018, approximately 22 years
- Heritage: Subaru’s mainstream engine displacement for passenger car, SUV, and performance applications
Subaru 2.5L Boxer Family Variant Reference
Phase I (1996-1998):
- EJ25D: Original 2.5L boxer DOHC variant, 165 HP
- Applications: Outback Limited, Legacy GT, Forester (early), Impreza 2.5 RS
- DOHC architecture
- Early head gasket reliability concerns (the seed of later 2.5L head gasket reputation)
Phase II SOHC NA (1999-2010):
- EJ251 / EJ252 / EJ253 / EJ254: Various Phase II SOHC NA variants
- 165-175 HP at 5,600-6,000 RPM
- 166-174 lb-ft torque at 4,000 RPM
- SOHC architecture (single overhead cam per bank)
- Applications: Impreza 2.5L NA, Legacy 2.5L NA, Outback 2.5L NA, Forester 2.5L NA, Baja
- External head gasket leak pattern documented (covered specifically in our EJ253 listing)
DOHC Turbo Variants (2002 plus):
- EJ255 (WRX Turbo): 224-265 HP at 5,200-6,000 RPM, DOHC, AVCS
- EJ257 (STI Turbo): 293-310 HP at 6,000-6,400 RPM, DOHC, AVCS, semi-closed deck block
- Compression ratio: approximately 8.4:1 (lower for boost)
- Turbocharger: IHI VF-series turbo (varying versions)
- Applications: Subaru WRX Turbo (EJ255), Subaru STI (EJ257), Legacy GT Turbo, Forester XT, Outback XT
- Internal head gasket failure pattern (less common than SOHC NA external leak)
Phase III Refinements (later variants):
- Various refinements to address head gasket concerns and improve efficiency
- AVCS variable valve timing on some later SOHC variants
- Updated cylinder head and head gasket designs
Critical Buyer Guidance: Variant-Specific Verification Required
The broader Subaru 2.5L family covers multiple substantially different engines. Critical for ordering:
- Turbo vs NA: Substantially different engines that cannot be cross-applied (compression ratio, cylinder head architecture, ECU calibration, fuel system, cooling capacity, internal components all differ)
- SOHC vs DOHC: Different cylinder head architectures with different valvetrain and timing belt arrangements
- Phase I / II / III year: Different production-year refinements may not be cross-compatible
- EJ25 vs FA20: The FA family (per our listing) is a completely different modern engine, NOT compatible with EJ family despite both being Subaru boxers
- Specific engine code (EJ251 / EJ252 / EJ253 / EJ254 / EJ255 / EJ257): Variants within the broader family may have differences in ECU calibration, accessory drive, and ancillary components
For specific variant deep-dives across our listings: EJ25 with turbo and non-turbo distinction (Impreza / Legacy / Outback / Forester / WRX / STI), EJ253 SOHC NA specifically (Subaru 2.5 SOHC NA detailed). This listing provides the broader Subaru 2.5L family overview. Call (855) 634-4447 to confirm your specific variant requirement.
Head Gasket Concern: The Subaru 2.5L Family Heritage
The Subaru 2.5L boxer family has well-documented head gasket concerns across the broader family. This is a known reliability concern that defines the 2.5L family’s reputation:
- SOHC NA (Phase II 1999-2010): External head gasket leak pattern (coolant leaks externally from head gasket); head gasket replacement is a common service item for high-mileage examples
- DOHC Turbo (EJ255 / EJ257): Internal head gasket failure pattern (coolant intrusion into combustion chamber); less common but more severe when it occurs
- Aftermarket MLS gaskets: Multi-layer steel head gaskets are a common upgrade during head gasket replacement to extend service life
- Subaru service history: Subaru issued service campaigns and updated head gasket designs to address the concerns over the production span
- Honest disclosure: Head gasket condition is assessed on every used Subaru 2.5L engine before sale
Subaru Boxer Engine Family Context
The Subaru 2.5 (this listing) covers the broader 2.5L Subaru boxer engine family overview. For specific variant deep-dives and modern boxer alternatives across our catalog, the Subaru EJ25 engine (our listing, with turbo and non-turbo distinction and detailed variant coverage of EJ25 turbo EJ255 / EJ257 and EJ25 non-turbo SOHC and DOHC variants) covers the EJ25 family in greater specific detail. The Subaru FA20 engine (our listing, the modern Subaru / Toyota co-developed FA family 2.0L boxer with FA20D NA for BRZ / 86 / FR-S and FA20DIT turbo for WRX 2015 plus) is the modern FA family successor with direct injection. The Subaru EJ253 engine (our listing) covers the SOHC NA EJ253 variant specifically. Four Subaru boxer engine listings across : EJ25 turbo and non-turbo, FA20 modern direct-injection, (this listing) Subaru 2.5 broader family overview, EJ253 SOHC NA specifically.
Vehicle Compatibility
| Feature | EJ25 NA SOHC (Older) | FB25 (Current) |
|---|---|---|
| Production | 1995-2013 | 2011-present |
| Displacement | 2,457 cc | 2,498 cc (slightly larger) |
| Bore x Stroke | 99.5 x 79 mm | 94 x 90 mm |
| Valvetrain | SOHC | DOHC |
| AVCS | Limited / no | Standard (intake + exhaust) |
| Block Design | Open-deck (head gasket prone) | Semi-closed deck (improved) |
| HP (Standard) | 165-173 HP | 170-185 HP |
| Head Gasket Service | Common at 100k-150k miles | Far less common |
| Oil Consumption | Generally low | Higher on 2011-2014 (known issue) |
| Used Engine Cost | $1,000-2,500 | $1,200-3,500 |
Subaru 2.5L Family Variant Reference
| Vehicle | Years with FB25 | Notes |
|---|---|---|
| Subaru Forester | 2011+ (4th gen onward) | Standard non-turbo |
| Subaru Outback | 2010+ (5th gen onward) | Standard 4-cylinder |
| Subaru Legacy | 2010+ (6th gen onward) | Standard 4-cylinder |
| Subaru Crosstrek | 2018+ (2nd gen) | Replaced previous 2.0L FB20 |
| Subaru Ascent | Some variants 2019+ | Primarily uses FA24F turbo |
Phase I / Phase II / Phase III Production Timeline
| Vehicle | Compatibility |
|---|---|
| Vehicle | Years with EJ25 NA |
| Subaru Impreza (2.5 non-turbo) | 1996-2011 |
| Subaru Forester (non-XT) | 1998-2010 |
| Subaru Outback (non-turbo) | 1996-2012 |
| Subaru Legacy (non-turbo) | 1996-2012 |
| Subaru Baja | 2003-2006 |
Head Gasket Concern Reference
| Vehicle | Compatibility |
|---|---|
| Subaru Forester | 2011 onward (4th gen, 5th gen with FB25) |
| Subaru Outback | 2010 onward (5th gen, 6th gen with FB25) |
| Subaru Legacy | 2010 onward (6th gen, 7th gen with FB25) |
| Subaru Crosstrek | 2018 onward (2nd gen with FB25) |
| Subaru Ascent | 2019 onward (some variants with FB25, primary engine FA24F turbo) |
Common Failure Modes and Maintenance Reference
| Vehicle | Compatibility |
|---|---|
| Subaru Impreza (2.5 NA) | 1996-2011 |
| Subaru Forester (Non-XT) | 1998-2010 |
| Subaru Outback (Non-Turbo) | 1996-2012 |
| Subaru Legacy (2.5L Non-Turbo) | 1996-2012 |
| Subaru Baja | 2003-2006 |
Why Buy From Part Nests
- Engine family verified as Subaru 2.5L boxer (EJ25 family covering NA EJ251 / EJ252 / EJ253 / EJ254 / EJ255 / EJ257 variants)
- Year and variant confirmed (Phase I 1996-1998, Phase II SOHC 1999-2010, DOHC turbo 2002 plus, Phase III refinements)
- Application confirmed (Impreza, Legacy, Outback, Forester, Baja, WRX Turbo, STI)
- Horsepower rating documented (165-310 HP across family variants)
- Compression and leak-down tested all 4 cylinders
- Both cylinder heads condition documented (boxer-4 with two heads)
- Head gasket condition assessed (CRITICAL Subaru 2.5L family concern)
- Timing belt condition assessed
- Free shipping to all 50 states via heavy freight
- 15 day replacement warranty on internal defects
- Subaru-experienced support team familiar with 2.5L family variants and head gasket history
- Call (855) 634-4447 to verify application against your VIN before you order.
15 Day Replacement Warranty
Every used Subaru 2.5L engine purchased through Part Nests carries a 15 day replacement warranty starting on the delivery date.
What Is Covered
- Internal defects already present when the engine arrives
- Compression failures on any of the 4 cylinders beyond what was disclosed
- Cylinder head crack failures within 15 days from installation (both heads on the boxer-4)
- Block crack failures within 15 days from installation
- Connecting rod, bearing, or crankshaft failures within 15 days from installation
- Head gasket failures within 15 days from installation (where head gasket condition was documented as serviceable; the well-documented Subaru 2.5L family head gasket concern is honestly disclosed before sale)
- Turbocharger internal failures within 15 days from installation (turbo variants where turbocharger was supplied and tested)
- Timing belt failures within 15 days from installation (where timing belt was documented as serviceable)
- AVCS solenoid failures within 15 days from installation (AVCS variants)
- Incorrect variant shipped (NA vs Turbo, SOHC vs DOHC, Phase mismatch where variant was documented) due to an error on our end
What Is Not Covered
- Damage caused during installation
- Damage from incorrect engine oil (Subaru specifies 5W-30 conventional or 0W-20 synthetic depending on year)
- Damage from extended oil change intervals (3,750-5,000 mile intervals strongly recommended given head gasket concern; turbo variants require shorter 3,000-3,750 mile intervals)
- Damage from contaminated fuel (turbo variants require 91 octane minimum)
- Damage from a single overheating event (cooling integrity is critical given head gasket concerns)
- Damage from cross-application (NA installed where turbo was ordered without ECU and fuel system and cooling verification, or vice versa; SOHC installed where DOHC was ordered without cylinder head and timing belt verification, or vice versa)
- Damage from neglected timing belt replacement (every 105,000 miles is critical; failure damages interference engine)
- External components (intake manifold, exhaust manifolds, turbocharger if not supplied or noted as ancillary, ECU and wiring harness, accessory drive, transmission, AC compressor, alternator, starter, fuel tank, fuel lines outside engine) unless itemized
- Labor expenses of any kind
To start a warranty claim, reach us within 15 days of delivery at (855) 634-4447.
- All 4 Cylinders Compression and Leak-Down Tested: Results documented before payment
- Engine Family Verified: Subaru 2.5L boxer (EJ25 family covering multiple variants)
- Year and Variant Confirmed: Phase I / Phase II SOHC / DOHC turbo / Phase III refinements
- Application Confirmed: Impreza / Legacy / Outback / Forester / Baja / WRX / STI
- Horsepower Rating Documented: 165-310 HP across family variants
- Both Cylinder Heads Documented: Boxer-4 with two heads
- Head Gasket Condition Assessed: CRITICAL Subaru 2.5L family concern
- 15 Day Replacement Cover: Internal defects protected from delivery onward
Additional information
| Brand | Subaru |
|---|---|
| engine-type | Flat-4 (horizontally opposed boxer), naturally aspirated |
| engine-families | FB25 (current 2011+) and EJ25 NA SOHC (older 1995-2013) |
| manufacturer | Subaru Corporation |
| hp-range | 165 HP (EJ251) to 185 HP (latest FB25) |
| torque-range | 166 lb-ft (EJ25) to 178 lb-ft (FB25) |
| displacement | 2.5L (FB25 2, 498 cc / EJ25 2, 457 cc) |
| fb25-bore-x-stroke | 94.0 mm x 90.0 mm |
| ej25-bore-x-stroke | 99.5 mm x 79.0 mm |
| fb25-valvetrain | DOHC, 16 valves, AVCS on intake + exhaust |
| ej25-na-valvetrain | SOHC, 16 valves |
| aspiration | Naturally aspirated (both families) |
| fuel-system | Sequential multi-port injection (most), direct injection (later FB25) |
| fuel-type | Regular 87 octane (both NA families) |
| block-material | Aluminum (semi-closed deck FB25, open-deck EJ25) |
| head-material | Aluminum |
| cooling-system | Liquid cooled |
| fb25-production | 2011-present |
| ej25-na-production | 1995-2013 |
| fb25-direct-fit | Forester / Outback / Legacy / Crosstrek / Ascent |
Subaru's mainstream 2.5L displacement spanning 22 years across multiple variants. The Subaru 2.5L boxer engine family represents Subaru's mainstream displacement for passenger car, SUV, and performance applications across more than two decades of production. The 2.5L boxer family encompasses multiple variants and phases: the original EJ25 introduced in 1996 (Phase I), the revised EJ25 Phase II 1999-2010 with SOHC heads on most NA variants, the DOHC turbo variants EJ255 (WRX Turbo) and EJ257 (STI Turbo), and the refined Phase III variants. The 2.5L displacement is Subaru's mainstream engine option used across Impreza, Legacy, Outback, Forester, Baja, WRX Turbo, and STI applications. Specifications: 2.5 liters displacement (2,457 cc), horizontally-opposed boxer-4 (180-degree opposed cylinders), bore x stroke 99.5 mm x 79 mm consistent across family, aluminum block, port fuel injection (NOT direct injection in EJ family), timing belt driven.
Multiple variants across Phase I, Phase II SOHC, DOHC turbo, and Phase III refinements. Phase I (1996-1998): EJ25D original 2.5L boxer DOHC variant, 165 HP, applications Outback Limited / Legacy GT / Forester early / Impreza 2.5 RS, DOHC architecture, early head gasket reliability concerns. Phase II SOHC NA (1999-2010): EJ251 / EJ252 / EJ253 / EJ254 various Phase II SOHC NA variants, 165-175 HP, 166-174 lb-ft torque, SOHC architecture, applications Impreza 2.5L NA / Legacy 2.5L NA / Outback 2.5L NA / Forester 2.5L NA / Baja. DOHC Turbo Variants (2002 plus): EJ255 WRX Turbo 224-265 HP DOHC AVCS, EJ257 STI Turbo 293-310 HP DOHC AVCS semi-closed deck block, applications WRX Turbo / STI / Legacy GT Turbo / Forester XT / Outback XT. Phase III Refinements: various refinements to address head gasket concerns and improve efficiency, AVCS on some later SOHC variants, updated head gasket designs.
Well-documented head gasket concern across the family. The Subaru 2.5L boxer family has well-documented head gasket concerns across the broader family. This is a known reliability concern that defines the 2.5L family's reputation. SOHC NA (Phase II 1999-2010): external head gasket leak pattern (coolant leaks externally from head gasket); head gasket replacement is a common service item for high-mileage examples. DOHC Turbo (EJ255 / EJ257): internal head gasket failure pattern (coolant intrusion into combustion chamber); less common but more severe when it occurs. Aftermarket MLS gaskets: multi-layer steel head gaskets are a common upgrade during head gasket replacement to extend service life. Subaru service history: Subaru issued service campaigns and updated head gasket designs to address the concerns over the production span. Honest disclosure: head gasket condition is assessed on every used Subaru 2.5L engine before sale.
Multiple verification points before ordering. The broader Subaru 2.5L family covers multiple substantially different engines. Critical for ordering: turbo vs NA (substantially different engines that cannot be cross-applied; compression ratio, cylinder head architecture, ECU calibration, fuel system, cooling capacity, internal components all differ); SOHC vs DOHC (different cylinder head architectures with different valvetrain and timing belt arrangements); Phase I / II / III year (different production-year refinements may not be cross-compatible); EJ25 vs FA20 (the FA family per our listing is a completely different modern engine, NOT compatible with EJ family despite both being Subaru boxers); specific engine code (EJ251 / EJ252 / EJ253 / EJ254 / EJ255 / EJ257) variants may have differences in ECU calibration, accessory drive, and ancillary components. Call (855) 634-4447 to confirm your specific variant requirement.
Four Subaru boxer engines in. The Subaru 2.5 (this listing) covers the broader 2.5L Subaru boxer engine family overview. The Subaru EJ25 engine covers the EJ25 family in greater specific detail with turbo and non-turbo distinction and detailed variant coverage of EJ25 turbo EJ255 / EJ257 and EJ25 non-turbo SOHC and DOHC variants (Impreza / Legacy / Outback / Forester / WRX / STI applications). The Subaru FA20 engine is the modern Subaru / Toyota co-developed FA family 2.0L boxer with FA20D NA for BRZ / 86 / FR-S and FA20DIT turbo for WRX 2015 plus (the modern FA family successor with direct injection). The Subaru EJ253 engine covers the SOHC NA EJ253 variant specifically. Four Subaru boxer engine listings across : EJ25 turbo and non-turbo, FA20 modern direct-injection, (this listing) Subaru 2.5 broader family overview, EJ253 SOHC NA specifically.
Head gasket primary concern plus several other documented modes. Head gasket failure: documented Subaru 2.5L concern across the family (SOHC NA external leak pattern, DOHC turbo internal leak pattern); primary maintenance / repair item. Timing belt wear: every 105,000 miles maintenance critical; failure damages interference engine. Spark plug access: spark plug access on horizontally-opposed boxer is more difficult than inline engines; budget extra labor for plug service. Knock sensor failure: common cause of check engine codes. AVCS solenoid wear: variants with AVCS variable valve timing. Turbocharger wear (turbo variants): IHI VF-series turbo can wear at high mileage; turbo failure on WRX / STI applications is well-documented at 100,000-150,000 miles depending on maintenance. Oil consumption with age: some 2.5L examples exhibit elevated oil consumption past 100,000 miles.
Head gasket assessment, timing belt, spark plugs, turbo inspection (turbo variants). After acquiring a used Subaru 2.5L engine, budget for these items. Head gasket assessment: budget $1,500-3,000 for proactive MLS head gasket replacement at acquisition if existing gaskets are at high mileage (recommended for high-mileage examples given the well-documented family concern). Timing belt service: budget $800-1,500 for full timing belt service including water pump, tensioner, idler pulleys; every 105,000 miles is critical. Spark plug replacement: budget $200-400 (labor higher than inline engines due to boxer access). Knock sensor inspection: replace if codes present. Turbo inspection (turbo variants): budget $1,500-3,500 for turbo replacement if turbo is at high mileage. Strict synthetic oil maintenance: 3,750-5,000 mile intervals (NA), 3,000-3,750 mile intervals (turbo). Quality 91 octane fuel minimum for turbo variants.
No. There is no core return required.
2 reviews for Subaru 2.5 Engine for Sale | OEM Used Subaru 2.5 Liter Horizontally-Opposed
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Hyacinth M. –
Bought for my Subaru 2.5 Engine. Second time using Part Nests, still solid.
Theodore P. –
Right fit for the Subaru 2.5 Engine. Rep knew what they were talking about.