Parts for your 2021 Subaru Xv-Head gasket

2021 Subaru XV head gasket — what it does, when to worry, and how to look after it

Based on technical sources — the 2021 Subaru XV/Crosstrek Service Manual (FB engine), the Subaru Australia XV 2021 Owner’s Manual specifications, and Subaru Global technical literature on the FB-series 2.0‑litre DOHC boxer — the 2021 Subaru XV (including e‑Boxer hybrid) uses conventional multi‑layer steel head gaskets. Being a flat‑four, it has two cylinder heads and therefore two head gaskets, one per bank.

On the 2021 Subaru XV, the head gasket’s job is straightforward but critical: it seals each aluminium cylinder head to the aluminium engine block to contain combustion pressure while keeping engine oil and coolant in their own passages. Subaru’s FB20 engine runs modern multi‑layer steel (MLS) gaskets that handle heat cycles and pressures far better than the older generations, which is why failures are now uncommon when the cooling system is well maintained.

This isn’t a routine service item, but it does benefit from sensible preventative care. During regular servicing, a technician should keep an eye out for tell‑tales and keep the cooling system healthy. Owners who stay on top of coolant and temperature management usually enjoy trouble‑free motoring.

• Keep the cooling system happy: use the correct Subaru long‑life blue coolant and refresh it per the maintenance schedule. Mixing coolants or running low on coolant is a fast track to overheating, which can stress gaskets and heads.
• Watch the basics: any unexplained coolant loss, sweet‑smelling steam from the exhaust after warm‑up, milky residue under the oil cap, overheating, bubbles in the overflow tank, or an external weep at the head‑to‑block seam deserves a professional look.
• Test, don’t guess: if symptoms pop up, a cooling‑system pressure test, chemical block test for combustion gases in coolant, and cylinder leak‑down test will confirm what’s going on.
• If replacement is needed: it’s a big job on an FB‑series boxer and best done by a Subaru‑savvy workshop. Expect engine-out procedures, precise torque‑angle sequences, and cam timing setup. Smart add‑ons while you’re there include new head bolts, thermostat, radiator cap, and any tired hoses. Heads should be checked and lightly machined if out of flat, and new MLS gaskets (genuine or OEM‑quality) fitted on both banks.
• Final touch: refill with the correct coolant and vacuum‑bleed to avoid airlocks. A brief re‑torque isn’t required on MLS gaskets, but the torque‑angle procedure must be followed to the letter.

Looked after properly, the XV’s FB20 head gaskets are quiet achievers — they just get on with the job for many hundreds of thousands of kilometres.

Does the 2021 Subaru XV have two head gaskets?

Yes. The FB20 is a horizontally opposed (boxer) four‑cylinder, so it has two cylinder heads — left and right — and therefore two head gaskets. When major work is needed, most workshops replace both gaskets to keep each bank matched for long‑term reliability.

Are head gasket failures common on the 2021 XV?

No. The FB‑series engines use improved multi‑layer steel gaskets and run cooler, cleaner, and more consistently than the older EJ engines that earned Subaru some head‑gasket notoriety years ago. With proper coolant and no overheating events, failures are relatively rare.

What are the early signs a head gasket might be failing on an XV?

Red flags include unexplained coolant loss, overheating on climbs, persistent bubbles in the overflow, sweet white exhaust steam after warm‑up, or milky discolouration in the oil. If any of these show up, get a pressure test and a chemical test for combustion gases in the coolant before driving further.