The 2007 Forester with the 2.5L naturally-aspirated EJ253 is generally reliable but prone to the classic Subaru head gasket failure, plus automatic transmission cooler line corrosion that can grenade the transmission if ignored.
External Head Gasket Failure (EJ253 Engine)
Common · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Oil seepage visible on outside of engine block below heads, Coolant drips on ground after sitting, Sweet smell from engine bay, Slow coolant consumption without visible leaks elsewhere
Fix: Replace both head gaskets, resurface heads if warped, timing belt/water pump/thermostat while open. 12-16 labor hours at indie shop. Catch it early before coolant mixes with oil internally.
Estimated cost: $1,800-2,500
Transmission Oil Cooler Line Corrosion (4EAT Auto Only)
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Red transmission fluid pooling under engine bay, Sudden transmission slipping or failure to engage, Overheating transmission, Metal lines at radiator visibly rusted through
Fix: Replace corroded steel cooler lines with aftermarket stainless or OEM. If delayed and coolant mixes into transmission, you're looking at full transmission rebuild or replacement. Line replacement alone: 2-3 hours labor.
Estimated cost: $300-600 for lines only; $2,500-4,000 if transmission contaminated
Front Lower Control Arm Rear Bushing Failure
Common · medium severityTypical onset: 100,000-140,000 mi
Symptoms: Clunking over bumps at low speed, Steering wander or vague feel, Inner front tire wear, Visible cracking or tearing of rubber bushing
Fix: Replace front lower control arms (bushings not sold separately on most aftermarket). Alignment required. 2.5-3.5 hours labor for both sides.
Estimated cost: $400-700
Rear Wheel Bearing Failure
Occasional · medium severityTypical onset: 110,000-160,000 mi
Symptoms: Humming or growling from rear that increases with speed, Noise changes with gentle side-to-side swerving, ABS light may come on, Rear hub hot to touch after driving
Fix: Replace rear hub assembly (bearing pressed into hub, replaced as unit). 1.5-2 hours per side. Rear differential fluid should be inspected if bearing failed catastrophically.
Estimated cost: $250-400 per side
Engine Piston Slap / Ringland Failure (Less Common, Early Internal Damage)
Rare · high severityTypical onset: 60,000-100,000 mi
Symptoms: Cold-start knocking for first 30-60 seconds that goes away when warm, Loss of compression on cylinder(s), Check engine light with misfire codes, Excessive oil consumption (more than 1 qt per 1,000 mi)
Fix: Piston slap alone (piston skirt worn) may not require immediate repair if compression good, but ringland failure means short block replacement or full engine rebuild. 18-24 hours labor for short block swap.
Estimated cost: $3,500-5,500 for short block; $5,000-7,500 for full rebuild
Catalytic Converter Substrate Failure
Occasional · low severityTypical onset: 130,000-180,000 mi
Symptoms: Check engine light P0420 (catalyst efficiency), Slight loss of power at highway speeds, Rattle from under car on cold start if substrate broken apart, Fuel economy drops 1-2 mpg
Fix: Replace front catalytic converter (part of front Y-pipe assembly). Some opt for aftermarket high-flow or used OEM to save cost. 2-3 hours labor, bolts often seized.
Estimated cost: $600-1,200 with OEM cat; $300-500 aftermarket
Buy one if the head gaskets and transmission cooler lines have been done; avoid high-mileage examples with no service records or visible oil leaks—budget $2,500 for deferred maintenance.
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.