The 2004 Legacy GT brought turbocharged EJ20 performance to the midsize sedan market, but turbos and head gaskets define ownership. Budget for major engine work if you're buying high-mileage.
Head Gasket Failure (EJ20 Turbo)
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: external oil seepage around cylinder head perimeter, coolant consumption without visible leaks, white smoke on cold start, overheating under load
Fix: Both head gaskets, machine work on heads if warped, timing components while apart. 16-20 labor hours. Many shops recommend doing timing belt, water pump, cam and crank seals simultaneously since you're already there.
Estimated cost: $2,800-4,200
Turbocharger Failure
Occasional · high severityTypical onset: 100,000-140,000 mi
Symptoms: blue smoke under boost, loss of power above 3000 rpm, loud whine or grinding from turbo, oil consumption jumps suddenly, check engine light with boost control codes
Fix: Turbo replacement requires removing exhaust manifold, downpipe, intercooler piping. OEM turbos are expensive; many go aftermarket. 8-12 labor hours depending on stud condition.
Estimated cost: $1,800-3,500
Transmission Mount Collapse
Common · medium severityTypical onset: 70,000-110,000 mi
Symptoms: clunk on throttle lift or engagement, excessive drivetrain movement visible in engine bay, vibration at idle in gear, shifter slop increases
Fix: Rear transmission mount (pitch stop) is the usual culprit. Requires lifting transmission slightly. 2-3 labor hours. Often replace front engine mounts at same time if showing cracks.
Estimated cost: $350-650
Lifter Tick / Valve Train Noise
Common · medium severityTypical onset: 60,000-120,000 mi
Symptoms: ticking or tapping from cylinder heads at idle, worse cold, noise follows engine RPM, sometimes quiets with higher oil pressure, CEL for misfire if severe
Fix: EJ20 lifters wear or collapse. Requires cam removal on affected bank. If doing both banks, 10-14 labor hours. Many techs inspect cam lobes for wear at same time—replace if pitted.
Estimated cost: $1,200-2,200
Transmission Oil Cooler Line Leaks
Occasional · medium severityTypical onset: 90,000-130,000 mi
Symptoms: ATF drips near radiator or underneath, low fluid level on dipstick, transmission slipping or delayed engagement, burnt ATF smell
Fix: Lines rust or fitting o-rings fail. Replacement lines and fresh fluid. 2-3 labor hours if just lines; more if cooler itself is leaking.
Estimated cost: $400-800
Harmonic Balancer / Crank Pulley Separation
Occasional · high severityTypical onset: 100,000+ mi
Symptoms: vibration at idle that increases with RPM, serpentine belt mis-tracking or squealing, visible wobble on crank pulley, accessory drive issues
Fix: Rubber damper ring separates from hub. Requires timing cover removal to access. 4-6 labor hours. Critical to replace before it fails completely and damages timing components.
Estimated cost: $600-1,000
PCV System Clogging / Oil Consumption
Common · low severityTypical onset: 80,000+ mi
Symptoms: burning 1 qt every 1,000-2,000 mi, blue smoke on deceleration, oil in intake piping, rough idle
Fix: PCV valve in intake manifold clogs, creates crankcase pressure, blows oil past rings. Clean intake, replace PCV, check turbo for play. 2-3 labor hours.
Estimated cost: $250-500
Buy only if head gaskets and timing have been done recently with records, or budget $4k-6k for deferred engine work—otherwise a rewarding turbo Subaru.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.