Parts for your 2006 Subaru Forester-Head gasket

2006 Subaru Forester head gasket — what it does, why it matters, and how to look after it

Yes, the 2006 Subaru Forester uses head gaskets. That’s confirmed by Subaru’s Factory Service Manual for the MY06 Forester (covering the EJ253 and EJ255 boxer four) and the Subaru Electronic Parts Catalogue, which both detail the multi‑layer steel gasket that seals each cylinder head to the engine block. Independent workshop manuals for 1998–2008 Forester models also show the gasket’s spec, torque sequence, and replacement procedure.

The head gasket’s job is pretty vital: it keeps combustion pressure in, and coolant and oil in their own passages, so the engine holds compression and runs at the right temperature without mixing fluids. Because the Forester’s flat‑four has two cylinder heads, it has a head gasket on each side, and both need to seal perfectly under heat and load.

Owners of EJ25‑series engines will have heard about external coolant or oil seep at the head gasket on some vehicles. Subaru issued guidance over the years on using Subaru Cooling System Conditioner with the approved coolant on affected engines. That conditioner can help prevent or slow minor external seepage but isn’t a cure‑all for internal leaks or an overheating issue. Heat cycling, ageing coolant, and incorrect torqueing from past work are common contributors to problems.

• Early signs to watch: a sweet coolant smell, low coolant with no obvious drips, bubbles in the overflow, occasional misfire on cold start, white exhaust vapour after warm‑up, or “mayo” under the oil filler cap.

Servicing tips for a 2006 Forester head gasket’s longevity are pretty straightforward: stick with the correct Subaru‑approved coolant and replacement interval from the owner’s manual, keep the radiator cap and hoses in good nick, bleed the system properly after any cooling work, and consider the Subaru conditioner if specified for your engine and market. Good cooling system hygiene in Aussie and Kiwi conditions is everything.

If testing points to a failing head gasket (cooling system pressure test, block test for combustion gases, cylinder leak‑down), replacement is the proper fix. On Subaru boxers, many technicians prefer engine‑out for access. Best practice is to machine the heads if needed, use quality MLS gaskets, follow the exact Subaru torque/angle sequence, and fit fresh cam seals. It’s smart value to do the timing belt, water pump, thermostat, and idlers at the same time, especially around the 160,000 km mark, so the front of the engine is refreshed in one go.

Popular questions

Does a 2006 Subaru Forester actually have a head gasket?
Yes. Subaru’s 2006 Forester Factory Service Manual and the Subaru parts catalogue list a cylinder head gasket for both EJ253 (non‑turbo) and EJ255 (turbo) engines. It’s a normal, essential seal between each cylinder head and the block.

How long should a 2006 Forester head gasket last?
With the right coolant, proper warm‑up, and good cooling system maintenance, many run well beyond 200,000 km. Some EJ25s can develop external seep earlier, which is why regular checks and timely coolant service are worth their weight in gold.

Should both head gaskets be replaced at once?
On the flat‑four, yes—best practice is to do both sides together. The labour overlaps, and it’s the perfect time to sort the timing belt, water pump, thermostat, and idlers so the engine is sealed and sorted for years.