An engine that powered countless daily commutes and family adventures, the Subaru EJ251 is a workhorse that you can rely on for solid performance. Do not mistake this engine for any weak motor , while it may not be aggressive, it can still keep things interesting on winding roads. Featuring the landmark Subaru horizontally opposed boxer configuration, this motor has a low center of gravity that supports Subaru's reputation for great handling. While the EJ251 engine for sale here may not be as aggressive as its turbocharged siblings, this naturally aspirated engine has a Linear Power Band and responsive throttle that many drivers appreciate.
Maintain it properly and it will outlast many other engines in its class. The Subaru EJ251 Engine for sale here is perfect if you are looking for reliable performance in a 1999-2004 Subaru Forester, Outback, Legacy, or Impreza 2.5.
The Subaru EJ251 engine with its displacement of 2.5 liters and four-cylinder boxer design was part of Subaru's lineup from 1999 to 2004. The aluminum block and heads make the engine compact and lightweight, supporting better fuel efficiency and vehicle balance. The SOHC and four-valves-per-cylinder configuration strikes a good balance of simplicity and performance. The Subaru EJ251 engine for sale here delivers proven Subaru reliability with the iconic boxer rumble.
The EJ251 HP rating is one of the most-searched topics for this engine:
The 165 HP EJ251 output established the baseline for Subaru's 2.5L NA platform that continues today in the FB25 (which produces 170-185 HP).
This page is specifically for the EJ251 SOHC NA variant (1999-2004). Important distinctions from other EJ25 family variants:
If you have a 1999-2004 Subaru Forester (1st gen), Outback (2nd/3rd gen), Legacy (3rd gen), or Impreza 2.5 (including 2.5RS), the EJ251 is your engine. This dedicated EJ251 page is the right variant page for these applications.
| Detail | Description |
|---|---|
| Feature | Specification |
| Engine Type | Flat-4 (horizontally opposed boxer), NA |
| Valvetrain | SOHC per bank, 16 valves |
| Displacement | 2,457 cc |
| Bore x Stroke | 99.5 mm x 79.0 mm (oversquare) |
| Compression | 10.0:1 |
| HP | 165 HP at 5,600 RPM |
| Torque | 166 lb-ft at 4,000 RPM |
| Fuel System | Sequential multi-port injection |
| Fuel Required | Regular 87 octane |
| Block Material | Aluminum, open-deck design |
| Head Material | Aluminum |
| Production | 1999-2004 |
| Vehicle | Years with EJ251 | Notes |
|---|---|---|
| Subaru Forester (1st generation) | 1999-2003 | The original modern Forester, replaced 1998 Forester's earlier engine |
| Subaru Outback (2nd and 3rd generation) | 1999-2004 | The classic Outback that established the rugged wagon market |
| Subaru Legacy (3rd generation) | 1999-2004 | The Outback's sedan / wagon sibling |
| Subaru Impreza 2.5 | 1999-2004 | Including the legendary 2.5RS sport variant (1999-2004) |
The EJ251 powered the original Subaru Impreza 2.5RS , a beloved enthusiast variant that brought the 2.5L engine to the smaller Impreza chassis:
This is widely documented as a known Subaru service item, NOT a defect. Subaru even acknowledged the issue with extended warranties on some affected models. Properly serviced EJ251 engines (with updated MLS head gaskets) typically run reliably for another 100,000+ miles. The EJ251 is generally not a "bad engine" , it just has one known service item that needs to be addressed.
Here at Vaz Auto Solutions, you'll find this Subaru EJ251 engine for sale at the most reasonable price possible, with variant correctly identified (EJ251 SOHC NA specifically), donor vehicle confirmed, all 4 cylinders compression tested, head gasket condition assessed (critical EJ25 service item), timing belt condition assessed, and complete inspection.
| Vehicle | Compatibility |
|---|---|
| Subaru Forester (1st generation) | 1999-2003 with EJ251 SOHC NA non-turbo |
| Subaru Outback (2nd and 3rd generation) | 1999-2004 with EJ251 SOHC NA non-turbo |
| Subaru Legacy (3rd generation) | 1999-2004 with EJ251 SOHC NA non-turbo |
| Subaru Impreza 2.5 (including 2.5RS) | 1999-2004 with EJ251 SOHC NA 2.5 |
Engine variant verified (EJ251 SOHC NA specifically, NOT EJ253 / EJ255 / EJ257)
Donor vehicle confirmed (Forester 1999-2003, Outback 1999-2004, Legacy 1999-2004, or Impreza 2.5 1999-2004)
All 4 cylinders compression tested
Oil pressure verified at idle and operating speed
External coolant leak inspection (EJ25 typical failure mode)
Cross-contamination check (oil-coolant mixing test)
Cross-reference assistance across 1999-2004 Forester / Outback / Legacy / Impreza applications
| Engine Type | Flat-4 (horizontally opposed boxer), naturally aspirated, SOHC |
|---|---|
| Engine Variant | EJ251 specifically (SOHC NA 2.5L) |
| Engine Family | Subaru EJ-series |
| Manufacturer | Subaru Corporation |
| Configuration | Flat-4 horizontally opposed boxer |
| Displacement | 2.5L (2,457 cc) |
| Bore X Stroke | 99.5 mm x 79.0 mm |
| Horsepower | 165 HP at 5,600 RPM |
| Torque | 166 lb-ft at 4,000 RPM |
| Compression | 10.0:1 |
| Aspiration | Naturally aspirated |
| Fuel System | Sequential multi-port injection |
| Fuel Type | Regular 87 octane acceptable |
| Valvetrain | SOHC per bank, 16 valves |
| Block Material | Aluminum, open-deck design |
| Head Material | Aluminum |
| Cooling System | Liquid cooled |
| Production Years | 1999-2004 |
| Direct Fit | Forester 1999-2003, Outback 1999-2004, Legacy 1999-2004, Impreza 2.5 1999-2004 |
Contact (240) 301-0095 within 15 days. The EJ251 has a well-documented head gasket service item that is the buyer's responsibility to address at installation , this is not a defect but a known high-mileage service area.
