Parts for your 2010 Subaru Impreza-Drive belt tensioner

2010 Subaru Impreza drive-belt tensioner — is it actually there?

For the 2010 Subaru Impreza fitted with EJ-series engines (2.0, 2.5, WRX/STI), a conventional spring-loaded accessory drive-belt tensioner isn’t used. Instead, these models run two separate V-ribbed belts that are manually adjusted — one for the alternator/power steering and one for the air-conditioning. This setup is detailed in the Subaru Factory Service Manual for 2008–2011 Impreza GE/GH/GR models in the Engine (ME) Drive Belt sections, which describe belt tension checks and adjustment using lock bolts and an adjuster screw, with no automatic tensioner in the layout. Australian and New Zealand parts catalogues from Gates and Dayco echo this: they list belts and an idler/adjuster for the A/C belt, but no automatic accessory-belt tensioner for the 2010 EJ engines. Automatic serpentine-belt tensioners appear on later FB-series Impreza models (from the 2012 generation), not this one.

Why did Subaru skip the auto tensioner here? The EJ accessory drive uses a simple, robust arrangement: the alternator pivots on a slotted bracket to set tension for its belt, and the A/C belt tension is set by an adjuster/idler. Fewer moving parts means fewer things to fail, and it suits the twin-belt layout. It’s worth noting there is a timing belt tensioner on these engines, but that’s a different, internal part under the timing covers — unrelated to the external accessory belts.

What should owners and workshops do during servicing instead of replacing a “tensioner”? Keep an eye on the belts themselves and the manual adjustment points:

• Inspect belt ribs for cracking, glazing, fraying, or chunking, and listen for squeal on cold starts.
• Check tension/deflection and adjust via the alternator bracket and the A/C adjuster as per the Subaru workshop specs. Retighten lock bolts correctly.
• Recheck tension after a short bedding-in period, as new belts can settle.
• Replace belts when wear is evident or on age/kilometre grounds as advised in the service schedule.

If a parts listing shows a “drive-belt tensioner” for a 2010 Impreza, it’s usually either a generic listing that suits later FB engines, or it’s referring to the timing belt tensioner. When ordering parts, specify “accessory/drive belts” and “A/C adjuster/idler” for EJ models to avoid mix-ups. Technical references: Subaru Factory Service Manual (GE/GH/GR, Engine: Drive Belt and A/C Belt adjustment procedures) and AU/NZ catalogues from Gates and Dayco that do not list an automatic accessory-belt tensioner for 2010 EJ engines.

Popular questions

Does a 2010 Subaru Impreza have a drive-belt tensioner?
No — not an automatic accessory-belt tensioner. The EJ-powered 2010 Impreza uses manual belt adjustment (alternator bracket and an A/C adjuster). This is shown in the Subaru workshop manual and reflected in AU/NZ parts catalogues, which don’t list an automatic tensioner for this year.

How are the accessory belts adjusted on a 2010 Impreza?
Tension for the alternator/power steering belt is set by moving the alternator on its slotted bracket, then tightening the lock bolts. The A/C belt uses an idler with an adjuster screw. Correct procedure and torque settings are in the Subaru service manual, so it’s best done by a qualified tech if you’re not confident.

Is the timing belt tensioner the same as a drive-belt tensioner?
Different part entirely. The timing belt tensioner sits behind the timing covers and keeps the timing belt correctly loaded. It’s replaced with the timing belt at the scheduled interval. The external accessory belts on the 2010 EJ engines don’t use an automatic tensioner.