` for FAQs maybe, or just `` + `
`. I'll stick to requested structure.
Structure:
```html
2002 Subaru Outback 2.5L 4-Cylinder Engine: Technical Overview
...
Architecture & Core Specifications
...
Performance & Power Delivery
...
Reliability Profile & Common Failure Points
...
Engine Comparison: 2002 Outback Powertrains
Preventive Maintenance & Longevity Protocol
...
Frequently Asked Questions
How reliable is the 2002 Subaru Outback 2.5L engine?
...
Does the 2.5L EJ251 engine require a timing belt or chain?
...
What is the average lifespan of the 2002 Outback 2.5L engine?
...
```
I'll fill in the content with precise, authoritative, SEO-optimized text. I'll ensure all technical details are accurate for the 2002 model year. I'll verify specs:
- 2002 Outback 2.5L: EJ251, 165 hp, 165 lb-ft, 5-speed manual or 4-speed auto, AWD
- Head gasket: MLS, but still prone to failure due to thermal cycling and aluminum head/iron block combo
- Timing belt: Yes, interval 105,000 miles
- Oil consumption: Common after 80k miles due to piston ring design
- Comparison table: EJ251 (2.5L NA), EJ255 (2.5L Turbo), EJ30 (3.0L H6)
I'll write the HTML carefully, ensuring semantic tags, proper table structure, and SEO-friendly headings/content. No markdown, raw HTML only.
6. **Self-Correction/Verification during drafting:**
- Check engine code: 2002 Outback 2.5L is indeed EJ251 (SOHC 16-valve). Some sources say DOHC, but 2002 is SOHC. Actually, Subaru switched to DOHC EJ25 in later years. 2002 is SOHC. I'll specify SOHC 16-valve.
- Power: 165 hp @ 5600 rpm, 165 lb-ft @ 4000 rpm (SAE net)
- Compression: 9.7:1
- Bore x Stroke: 92.0 mm x 93.0 mm
- Timing: Belt-driven, 105k mile replacement
- Head gasket: Multi-layer steel (MLS), but still fails due to coolant passage design and thermal stress
- Oil consumption: ~1 qt/1000 miles after 100k is common
- Table: I'll include columns for Engine Code, Displacement, Configuration, Horsepower, Torque, Timing, and Notable Trait
- FAQs: Directly address reliability, timing belt vs chain, lifespan
- SEO: Naturally integrate keywords, use proper heading hierarchy, keep paragraphs concise, add technical depth
- HTML: Clean, semantic, no markdown, valid structure
All checks pass. I'll generate the raw HTML now.
I'll make sure the output is strictly HTML, starting with `` or ``? The prompt says "Output clean semantic HTML only." I'll wrap in `` for semantic correctness, but I can also just output the body content. I'll use `` as the root. I'll avoid ``/``/`` unless necessary, but semantic HTML usually implies the structure. I'll just output the article content with proper tags.
Let's draft it carefully.
Structure:
```html
2002 Subaru Outback 2.5L 4-Cylinder Engine: Analytical Deep Dive
...
```
I'll ensure all requirements are met. No extra text. Raw HTML only. Proceed.
Self-Correction/Refinement during thought:
- Check if 2002 Outback 2.5L uses timing belt or chain: It uses a timing belt. Subaru switched to chains on some later engines, but EJ251 uses a belt.
- Head gasket: The 2002 model actually uses an improved MLS head gasket compared to late 90s, but failures still occur. I'll note this nuance for authority.
- Oil consumption: Piston ring gap design causes increased consumption after 80-100k miles.
- Table: I'll make it semantic with ``, ``, ``, ` | `.
- SEO: I'll naturally place keywords in H2/H3 and first paragraph.
- All good. Generating.
Output matches the response.✅
Structure looks solid. I'll produce it now.
*Self-Correction/Verification during generation prep*:
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