2004 SUBARU LEGACY GT

Typical onset: 80,000-150,000 mi

Symptoms: Sudden misfire on cylinder 4, White/blue smoke under boost, Rattling/knocking at idle after cold start, Loss of compression on one cylinder

Fix: Requires engine removal and full teardown. If caught early, single piston replacement with upgraded aftermarket forged piston (~18-22 hours labor). If detonation damaged cylinder wall or crank, you're into short-block territory (~25-30 hours). Almost always linked to aggressive tuning, poor-quality fuel, or running lean under boost.

Estimated cost: $3,500-7,500

Typical onset: 100,000-150,000 mi

Symptoms: Oil seepage at head/block mating surface, Oil smell after driving, Small puddles under car after sitting, No coolant mixing—just external weeping

Fix: Turbo models tend to leak oil externally rather than blow coolant internally like NA EJ25s. Engine-out job preferred for access to turbo hardware and exhaust studs. Both heads, timing components, water pump, all seals while you're in there. 20-24 hours labor with engine removal.

Estimated cost: $2,800-4,200

Typical onset: Not mileage-driven—age and salt exposure

Symptoms: Trans fluid dripping near radiator, Pink fluid puddle under front of car, Sudden loss of forward gears after leak, Burnt smell if driven low on fluid

Fix: Steel lines rust through where they pass behind the radiator. If you catch it early, replace lines and flush trans (~3-4 hours). If you drove it empty, you've destroyed clutch packs and need a rebuild or replacement trans (12-16 hours). Absolutely check these lines on any used purchase—they WILL fail in rust-belt states.

Estimated cost: $400-800 (lines only), $3,000-4,500 (with trans rebuild)

Typical onset: 90,000-140,000 mi

Symptoms: Hissing under boost, Slight loss of power/boost, CEL for lean condition (P0171/P0174), Visible crack in plastic Y-pipe behind intercooler

Fix: Plastic intake manifold Y-pipe develops cracks at stress points. Causes unmetered air and limp performance. Aftermarket aluminum replacements available and preferred. 2-3 hours labor—tight quarters but doable without engine removal.

Estimated cost: $350-600

Typical onset: 60,000-120,000 mi

Symptoms: Turbo whine or whistle changes pitch, Blue smoke on deceleration, Eventual turbo bearing failure, Low oil pressure to turbo (not visible without gauge)

Fix: Tiny filter screen inside turbo oil feed banjo bolt clogs with debris from engine break-in or poor oil change intervals. Starves turbo bearings. Remove bolt, clean or replace screen, verify oil feed line is clear. 1 hour labor. Preventive: do this every 60k or when doing head gaskets. If turbo already damaged, add another $1,200-1,800 for CHRA or replacement.

Estimated cost: $120-200 (preventive), $1,400-2,200 (with turbo damage)

Typical onset: 80,000-120,000 mi

Symptoms: Clunk when shifting from Park to Drive, Excessive drivetrain movement when launching, Vibration at idle in gear, Visible sagging or torn rubber on rear trans mount

Fix: Rear transmission mount (crossmember mount) tears or collapses. Allows excessive drivetrain motion and harsh engagement. Simple replacement, but requires supporting trans on jack. 1.5-2 hours labor. Use OEM or quality aftermarket—cheap mounts fail in 20k miles.

Estimated cost: $200-350

Typical onset: Not mileage-driven—heat-related

Symptoms: No-start when engine is hot, Cranks but won't fire after driving, Starts fine when cold, CEL for crank/cam correlation if it's failing intermittently

Fix: Sensor mounted low on block near oil pan, gets heat-soaked and fails. Engine cranks forever but won't start until it cools down. Replace sensor (1 hour labor from underneath). Verify reluctor ring on crank pulley isn't damaged while you're there—rare but catastrophic if teeth are missing.

Estimated cost: $180-280