Parts for your 2009 Subaru Impreza-Head gasket

2009 Subaru Impreza head gasket — purpose, problems, and when to replace

Yes, a head gasket is absolutely used on the 2009 Subaru Impreza. Factory technical sources that specify and illustrate this include the Subaru Impreza 2009 Factory Service Manual (Engine sections for EJ20/EJ25 petrol and EE20 diesel), Subaru FAST/OEM parts catalogues listing cylinder head gaskets for all 2009 Impreza engines (EJ253, EJ255/EJ257, EJ20, and EE20), and mainstream workshop data systems (e.g., Haynes/Autodata/Mitchell1) that provide procedures and torque sequences for head gasket replacement on these models.

The head gasket sits between the cylinder head and the engine block. Its job is to seal combustion pressure while also keeping engine oil and coolant in their own passages so they don’t mix. On the 2009 Impreza’s flat-four layout, it’s a critical multi-layer steel (MLS) seal that cops heat cycles and pressure every time the engine runs.

When a head gasket starts to fail, common signs owners may notice include:

• Unexplained coolant loss, overheating, or bubbling in the overflow bottle
• White exhaust smoke after warm-up, or a sweet smell from the exhaust
• Milky residue under the oil filler cap, rough cold starts, or misfires
• External coolant seepage at the head-to-block joint on EJ25 engines

Good servicing habits help: keep the cooling system healthy with the correct Subaru-approved coolant mix, replace coolant at the interval in the owner’s manual, ensure the radiator cap, thermostat, and hoses are in top nick, and use Subaru’s cooling system conditioner only where specified by Subaru technical guidance for applicable engines. Temperature spikes kill gaskets, so a clean, bled cooling system matters.

Replacement is a comprehensive job on a boxer engine and is best done on both banks at once. A quality repair typically includes:

• OEM-spec MLS head gaskets, new intake/exhaust gaskets, cam seals, and often head bolts
• Machine shop check and skim of cylinder heads if required, plus pressure testing
• “While you’re in there” items: timing belt kit with idlers/tensioner, water pump, thermostat, and fresh coolant
• Following the FSM torque/angle sequence precisely, then proper coolant bleed

For Aussie and Kiwi owners, budgeting for professional labour is wise given engine-out time on many workshops’ procedures. Caught early, a solid MLS gasket job restores reliability and keeps the Impreza happily racking up the k’s.

Popular questions

Do all 2009 Subaru Imprezas have head gasket issues?
Not all do. The EJ25 non-turbo models are more commonly reported for external coolant seep or internal leakage as kilometres climb, especially if cooling maintenance has been lax. Turbos (EJ255/EJ257) and EJ20/EE20 engines can also have issues, but proper cooling care and OEM-spec parts dramatically improve longevity.

How much does a head gasket job cost in Australia or New Zealand?
Costs vary with engine, parts quality, machining needs, and workshop rates. As a ballpark, many shops quote for 10–16 hours plus parts. With machining and a full timing belt/water pump kit, owners often see totals in the low-to-mid four figures. Getting an itemised quote helps compare apples with apples.

Is it safe to keep driving with a suspected head gasket leak?
Risky. A small leak can quickly escalate to overheating, warped heads, or bearing damage if coolant contaminates the oil. If symptoms appear, avoid heavy loads, monitor temperature, and have the vehicle inspected promptly to prevent bigger repair bills.