Parts for your 2007 Subaru Impreza-Drive belt pulley

2007 Subaru Impreza drive-belt pulleys: what they do and how to look after them

Based on the Subaru Factory Service Manual for the 2007 Impreza (EJ-series engines), the Subaru Electronic Parts Catalogue, and the Gates Australia Accessory Belt Drive System guide, the 2007 Subaru Impreza absolutely uses drive-belt pulleys. Both naturally aspirated and turbo EJ variants run V‑ribbed accessory belts with multiple pulleys, including the crankshaft (harmonic balancer) pulley, alternator, A/C compressor, power steering pump, and one or more idler/tensioner pulleys. Haynes coverage for 2002–2011 Impreza models echoes the same layout. So a drive-belt pulley is very much relevant on this model.

The drive-belt pulleys on a 2007 Subaru Impreza keep the essentials spinning: the alternator for charging, the A/C compressor for cool air, and the power steering pump for lighter steering. The crankshaft pulley (harmonic balancer) is the master driver, sending rotation through the belts to the rest. Note for EJ engines: the water pump is driven by the timing belt, not the accessory belts.

As part of regular servicing, it’s smart to inspect pulleys whenever the accessory belts are checked or replaced. Many Aussie and Kiwi workshops look over belts and pulleys every 12 months or 15,000 km, replacing belts at roughly 60,000–100,000 km depending on condition. Pulleys generally last longer, but idler and tensioner bearings can wear around the 100,000–150,000 km mark. If a pulley feels rough, wobbles, or howls, it’s due for replacement.

• Common warning signs: cold-start squeals or chirps, a steady whine, belt wandering on the pulley, visible pulley damage, or rubber separation on the crankshaft harmonic balancer.
• Tensioning setup varies: some EJ models use a spring-loaded tensioner, others use a screw-adjusted alternator bracket with a separate A/C idler. Always follow the FSM procedure for tension and alignment.
• When replacing belts, spin each pulley by hand (engine off) and check for play or noise. Any gritty feel or side-to-side wobble means the bearing is on the way out.

Good practice during any belt job is to clean pulley grooves, ensure the ribs track true, and torque fasteners to spec. If the crank pulley shows wobble or the rubber isolator is cracked or perished, fit a quality OEM-equivalent harmonic balancer. After any belt/pulley work, recheck tension and tracking after a few hundred kilometres.

Does the 2007 Impreza have one belt or multiple belts?

Many 2007 EJ25 non-turbo cars run two V‑ribbed belts (typically alternator/A/C and power steering), while some turbo variants use a main belt with a separate A/C sub-belt. The exact setup depends on engine and market spec. A quick look under the bonnet or a check against the Subaru FSM or parts catalogue will confirm your layout.

What noises point to a bad idler or tensioner pulley?

A brief squeal or chirp at cold start, a constant high-pitched whine, or a rhythmic chirp that changes with revs often means a pulley bearing is dry or failing. With the engine off, spin each pulley and listen/feel for roughness. If the noise changes when a light mist of water is sprayed onto the belt while idling, it can indicate belt slip or misalignment caused by a worn pulley.

Should the crankshaft harmonic balancer be replaced with the belt?

Not automatically. Inspect the balancer’s rubber layer for cracks, bulging, or separation, and watch for pulley wobble with the engine running. If any of those show up, replace it with an OEM or reputable aftermarket unit and torque the crank bolt to factory spec. When in doubt, follow the Subaru FSM procedure.