Parts for your 2004 Subaru Forester-Drive belt tensioner

2004 Subaru Forester drive-belt tensioner — is it actually there?

Short answer: a conventional spring-loaded accessory drive-belt tensioner isn’t fitted to the 2004 Subaru Forester (both non‑turbo and XT). This Forester runs two separate ribbed belts on the EJ engine, and belt tension is set manually via adjusters rather than an automatic tensioner unit.

Technical sources back this up. The Subaru Factory Service Manual for the 2004 Forester (SG, Engine section “Drive Belt” in the H4 SOHC/DOHC chapters) specifies belt adjustment by loosening the lock bolts and turning the adjuster screws on the alternator and idler, then re‑tightening. There’s no automatic accessory tensioner shown or referenced. Parts catalogues from Gates (ABDS/Accessory Belt Drive System) and Dayco for the same model years list belts and an idler, and note no separate automatic tensioner assembly for the accessory drive.

Why it isn’t used comes down to Subaru’s EJ layout. The twin‑belt setup is short, simple, and easy to set with basic tools, so an auto tensioner wasn’t necessary. It keeps costs down, is reliable, and gives the tech direct control over belt tension under the bonnet.

Worth noting: the engine’s timing belt does have a hydraulic tensioner, but that lives under the timing covers and is unrelated to the external accessory (drive) belts that run the alternator, A/C and power steering.

Servicing tips owners appreciate:

• Inspect the two accessory belts at every service for cracking, glazing, fraying, or noise on start‑up.
• To adjust:
  • Alternator/A/C belt — loosen the alternator pivot and lock bolts, use the long adjuster screw to set tension, then tighten to spec.
  • Power steering/A/C idler belt — loosen the idler pulley lock nut, turn the adjuster to set tension, re‑tighten the lock nut.
• Aim for firm tension without squeal, don’t over‑tighten or the bearings in the alternator, idler or A/C compressor can suffer.
• Recheck tension after a few hundred kilometres as new belts can bed in.

When in doubt, follow the Subaru service manual’s procedure and torque specs, or have a qualified technician set the belts. If squeal persists after a correct adjustment, check pulley condition and alignment, and consider replacing aged belts.

Popular questions

Does a 2004 Subaru Forester have a serpentine-belt tensioner?
No. It uses two separate accessory belts that are manually tensioned via the alternator and an idler adjuster. There’s no spring‑loaded serpentine tensioner on this model year and engine family.

How do you adjust the drive belts on a 2004 Forester?
With the engine off, loosen the relevant lock/pivot bolts, turn the adjuster screw to set belt tension, then tighten everything to spec. Check deflection and run the engine briefly, then recheck. If you’re unsure of torque values or belt play, follow the Subaru workshop manual.

Is the timing belt tensioner the same as the drive-belt tensioner?
Different parts entirely. The timing belt system uses a hydraulic tensioner under the front covers, and it’s serviced with the timing belt at the prescribed interval (often around 100,000 km in AU/NZ markets, check the owner’s schedule). The accessory drive belts are external and adjusted manually as needed.