Parts for your 2020 Subaru Impreza-Thrust bearing

2020 Subaru Impreza thrust-bearing: what it is, why it matters, and when to worry

Referencing Subaru’s technical literature for the FB20 engine used in the 2020 Subaru Impreza (Engine Mechanical section of the Subaru Service Manual, Subaru Technical Training on the FB engine family, and the Subaru parts catalogue for main bearing sets), this model is fitted with a crankshaft thrust bearing. It’s integrated into the rear main bearing (No. 5 journal) to control end-float of the crankshaft, so thrust-bearing is absolutely relevant to the 2020 Impreza.

The thrust bearing’s job is simple but crucial: it keeps the crankshaft from walking forwards and backwards under axial loads. Those loads come from things like the accessory belt drive, torque converter thrust (on CVT models), and clutch release forces (on manual variants in some markets). By managing that fore–aft movement, it protects the crank, block, and timing gear from expensive grief and helps the engine run smoothly and quietly.

It isn’t a routine service item. In normal use with good oil and sensible driving, a thrust bearing should last the life of the engine. What owners and workshops can do is look after the conditions that keep it healthy. Use the correct-spec 0W-20 engine oil, change it on time (typical dealer schedules are around every 12 months or 12,500 km in AU/NZ), and use a quality filter. Avoid accessory belt over‑tension, and don’t lug the engine. For manual cars, avoiding clutch riding reduces unnecessary axial load on the crank.

Warning signs of thrust wear tend to be indirect: glitter or ferrous particles in the oil, unstable idle timing or misfire codes tied to crank position variance, a dull knock that changes with axial load, or visible fore–aft movement of the crank pulley. On manual variants only, noise may change when the clutch pedal is depressed. Proper diagnosis means measuring crankshaft end-float against factory spec with a dial gauge, any out-of-spec reading warrants deeper inspection.

Replacement isn’t a driveway job. The FB20 uses a split crankcase, so the engine comes out, the case halves are separated, and the main bearings (including the thrust bearing shells) are selected and installed to graded specifications. Bearing clearances are verified (often with plastigauge), fasteners are torqued/angled, and cleanliness is paramount. It’s specialist labour, and a good time to inspect the crank, oil pump, and galleries. Prevention through clean oil and correct belt tension remains the smartest, cheapest play.

• Technical sources referenced: Subaru Impreza (2017–2021) Service Manual, Engine Mechanical (FB20) – Crankshaft and Main Bearings
• Subaru Technical Training – FB Engine Mechanical Overview
• Subaru Global Parts Catalogue – FB20 Main Bearing Set (includes thrust bearing shells)

FAQs

Does the 2020 Subaru Impreza have a thrust bearing?
The FB20 engine in the 2020 Impreza uses a thrust bearing integrated with the rear main journal to control crankshaft end-float. The CVT transmission also contains internal thrust elements, but they are not service items.

What are common symptoms of a worn thrust bearing on the FB20?
Metal in the oil, fore–aft crank pulley movement, timing stability issues, and a dull knock that varies with axial load. On manual variants only, noise may change when the clutch is pressed. Proper confirmation requires measuring end-float.

Can the thrust bearing be replaced without removing the engine?
No. The FB20’s split crankcase design means the engine must be removed and the case halves separated. Bearing grade selection and precise assembly make this a specialist workshop job.