Parts for your 2018 Subaru Forester-Exhaust gasket

2018 Subaru Forester exhaust gasket — what it does, where it lives, and when to replace it

Yes, the 2018 Subaru Forester uses exhaust gaskets. Subaru’s Factory Service Manual for the 2018MY Forester (Exhaust and Engine sections on TechInfo) specifies multiple gaskets at the manifold-to-head and pipe joints, and the Subaru FAST electronic parts catalogue lists “Exhaust Manifold Gasket” and “Gasket–Exhaust Pipe (donut)” among others for FB25 and FA20F models. Turbo variants add a turbo-to-front pipe gasket. Those technical sources make it clear the exhaust system relies on several gaskets to seal each flange and slip joint.

The exhaust gasket on a 2018 Forester plays a simple but critical role: it seals the joins so exhaust gas stays inside the pipes, the O₂ sensors read cleanly, and the cabin stays free of fumes. At the cylinder head, a multi-layer steel (MLS) manifold gasket handles heat cycles and prevents tick-like leaks on cold start. Further back, a metal “donut” gasket works with spring bolts to keep a flexible, leak-free seal between the front pipe and the rest of the system. At the rear, flat flange gaskets stop rasping and droning where the mid-pipe meets the muffler. Turbo models add a high-temp gasket at the turbo outlet.

Forester owners will usually only think about gaskets when something’s off. Common clues include a sharp ticking noise from the front of the engine when cold, a whiff of exhaust under the bonnet or near the floorpan, sooty marks around joints, or fuel trims going lean from an upstream leak. Any time an exhaust joint is undone—say, for a clutch, O₂ sensor, or muffler job—the gasket should be replaced as a matter of course. They’re crush seals, once compressed and heat-cycled, reusing them is a false economy.

Good practice for workshops in Australia and New Zealand is to inspect the Forester’s exhaust gaskets and spring bolts during routine servicing, especially on vehicles that see coastal air or gravel roads. Look for corrosion on studs and springs, warping on flanges, and black carbon tracks. Use quality OEM-spec gaskets, clean the mating faces, support the system so there’s no pre-load, and torque fasteners to Subaru specifications. After the first heat cycle, a quick re-check of fastener tension helps keep the seal quiet and tight for the long haul.

• Typical inspection window: every 20,000–30,000 km, or whenever the system is disturbed.
• Replace immediately if there’s noise, odour, visible soot, or failed emissions/WOF checks.

Popular questions

Does the 2018 Forester have more than one exhaust gasket?

It does. There are manifold-to-head gaskets, a front pipe donut gasket with spring bolts, and rear flange gaskets. Turbo models also use a turbo-to-front pipe gasket.

How often should exhaust gaskets be replaced on a 2018 Forester?

There’s no fixed interval. They’re replaced whenever a joint is disassembled or if there’s a leak. Regular inspections during servicing—especially on coastal cars—help catch issues early.

What are the signs of a blown exhaust gasket on this model?

A ticking sound at cold start, exhaust odour near the engine bay or underbody, black soot at a flange, louder exhaust note, or lean fuel trim codes can all point to a leaking gasket.