Parts for your 2010 Subaru Impreza-Head gasket

2010 Subaru Impreza head gasket — purpose, service tips, and when to replace

Technical sources confirm a head gasket is absolutely used on the 2010 Subaru Impreza. The Subaru Factory Service Manual for the 2010 Impreza (engine/cylinder head section), the Subaru FAST parts catalogue, and general service texts such as the Haynes manual for late-2000s Impreza all specify a head gasket fitted between the EJ-series flat-four engine block and each cylinder head.

On the 2010 Impreza (2.0 and 2.5‑litre EJ engines, including turbo variants), the head gasket’s job is to seal high-compression combustion in each cylinder while keeping the engine’s oil and coolant circuits separate. It’s a precision multi-layer steel gasket clamped by torque-and-angle tightened head bolts. Because Subaru’s boxer engines have two heads and see plenty of thermal cycling, correct torque sequence and cooling-system care are vital to long life.

While a head gasket isn’t a routine “wear item”, looking after the cooling system hugely reduces the risk of trouble. Stick with the correct Subaru long-life coolant, mix ratio and bleeding procedure noted in the workshop manual. Many EJ engines also specify Subaru coolant conditioner via service bulletins, if the engine code on the vehicle calls for it, adding the approved conditioner at coolant changes can help prevent external seepage. Keeping radiators, caps, thermostats and fans in good nick — and changing coolant at the right kilometre interval — helps stabilise temperatures and protects the gasket.

Typical warning signs include unexplained coolant loss, sweet smells from the exhaust, milky oil, bubbles in the overflow, pressurised hoses when cold, or overheating under load. If any of these pop up, it’s best to stop driving and have a cooling-system and combustion-leak test done before things escalate.

When replacement is needed, most workshops will remove the engine for access and do both head gaskets together. Smart add-ons while they’re in there include timing belt and idlers (on belt-driven models), water pump, cam/crank seals, and a thorough flush of the heater core. Heads should be checked for flatness and surface finish that suits multi-layer steel gaskets. Use genuine or high-quality MLS gaskets, follow the factory torque/angle sequence, and replace head bolts if out of spec. Turbo WRX/STI variants benefit from the OE turbo-grade gasket and meticulous cooling and oil maintenance. Done right, a fresh set of gaskets will go the distance for many more years and kilometres.

• Use correct coolant and bleeding procedure.
• Watch for early signs: coolant loss, overheating, exhaust steam.
• Combine head gasket work with timing and water pump service.

Popular questions about the 2010 Subaru Impreza head gasket

What are common signs of a failing head gasket on a 2010 Impreza?

Owners often notice coolant loss with no obvious leak, overheating under load, white steam from the exhaust after warm-up, or the overflow bottle bubbling. Oil may look milky, or the cooling system may hold pressure when cold. Any of these warrant immediate checks to prevent engine damage.

How long should a replacement take, and what else should be done at the same time?

Expect a couple of days in the workshop, as the engine is typically removed for access. It’s smart to add a timing belt kit, water pump, thermostat, radiator cap, and fresh coolant. Heads should be measured and resurfaced if required, and new gaskets and seals fitted throughout.

Is it safe to keep driving with a suspected head gasket leak?

Not recommended. Even a minor leak can quickly snowball into overheating, warped heads, and catalyst damage. If symptoms appear, reduce driving, avoid heavy load, and book a test. Early intervention is far cheaper than a full rebuild.