What goes wrong
The multi-layer steel (MLS) head gaskets on EJ25 engines, particularly early designs, are prone to failure. This allows combustion gasses to leak into the cooling system, or oil/coolant to leak externally, often visible as oil seepage around the cylinder heads.
Symptoms to watch for
- External oil or coolant leaks from cylinder heads
- White smoke from exhaust
- Overheating
- Coolant disappearing without visible leaks
- Bubbles in coolant reservoir
- Sweet smell of burning coolant
Root cause
The original equipment (OE) head gaskets on naturally aspirated EJ25 engines were susceptible to premature failure due to material and design shortcomings, specifically in the sealing beads between the coolant/oil passages and combustion chamber.
Buy time with these
- • Regularly check coolant levels and oil for contamination.
- • Address external leaks promptly to prevent further damage.
Permanent fix
- Replace head gaskets with updated multi-layer steel (MLS) gaskets, such as Subaru Part No. 11044AA642 (right) and 11044AA633 (left), or equivalent aftermarket MLS gaskets.
- Inspect cylinder heads for warpage and machine if necessary.
- Replace timing belt, water pump, and tensioner while accessible.
FAQ
What causes ej25 head gasket failure (2000-2009 legacy)?
The original equipment (OE) head gaskets on naturally aspirated EJ25 engines were susceptible to premature failure due to material and design shortcomings, specifically in the sealing beads between the coolant/oil passages and combustion chamber.
How much does it cost to fix?
National average $1,500–$2,500. Cost assumes replacement of both head gaskets, timing belt, water pump, and associated seals/gaskets. Higher end includes cylinder head machining if warpage is present.
Is this a DIY repair?
Difficulty 4/5. Replace head gaskets with updated multi-layer steel (MLS) gaskets, such as Subaru Part No. 11044AA642 (right) and 11044AA633 (left), or equivalent aftermarket MLS gaskets.
What are the symptoms?
External oil or coolant leaks from cylinder heads; White smoke from exhaust; Overheating; Coolant disappearing without visible leaks; Bubbles in coolant reservoir; Sweet smell of burning coolant