Engine
Timing belt idlers, tensioner and crank pulley wear
The belt itself rarely fails, but the grease-packed idler bearings, the hydraulic tensioner and the two-piece crank pulley do. A seized idler or a pulley whose rubber ring has let go can throw the belt or wear the crank keyway.
Frequency basis: Two damper-pulley failures logged on RepairPal for the 2005 Outback and a handful of idler and pulley threads; the EJ255 is an interference engine, so any of these failures can mean bent valves. Most reports are on other EJ25 variants with the same belt layout.
Symptoms
- Bearing whine or rattle from behind the belt covers; squeal from the accessory belts
- Visible wobble of the crank pulley; misfires from a loose pulley wearing the crank key
- Sudden loss of charging, power steering and A/C when an idler seizes and the accessory belt is thrown
- No-start with the belt jumped or broken (interference engine: valve damage likely)
Causes found
- Grease in the idler bearings dries out with age; cheap replacement idlers and water pumps fail early
- The crank pulley is two pieces bonded by rubber; the rubber deteriorates and the inertia ring slips
- A crank bolt torqued to an old spec can loosen over time
Check in this order
- Pull the belt covers at the 105,000-mile service and spin every idler by hand; replace any with roughness or play
- Watch the crank pulley with the engine running for wobble or a shifting timing mark
- Check the crank keyway for wear whenever the pulley is off
What fixed it
- Replace the belt, all idlers, the tensioner and the water pump together at the factory interval; use Japanese-bearing parts (Aisin, NTN, Koyo) rather than no-name kits
- New crank pulley, woodruff key and bolt when the pulley wobbles; a worn keyway was repaired with a new sprocket and key in one report
- Torque the crank bolt to the H4DOTC chapter figure, not an older EJ25 figure
References on this site
OEM parts
- 13033AA040Adjuster assembly, belt tensioner
- 13073AA142Idler complete, belt
- 13085AA080Idler complete, belt No. 2
- 12305AA252Pulley, crankshaft
- 21114AA051Gasket, water pump
Factory manual chapters
Maintenance guides
Sources
Forum threads are owner reports, not factory findings. Counts are from the threads and complaint records read for this page; read the sources before buying parts.
- 1.crank pulley wobble
subaruoutback.org · Forum thread · 2011, 1998 EJ25; two-piece pulley failure and keyway wear
- 2.Tensioner & Idler Pulley Question
subaruoutback.org · Forum thread
- 3.Timing Belt and Idler Pulley Replacement Failure?
ultimatesubaru.org · Forum thread · early failure of no-name idlers
- 4.2005 Subaru Outback Problems and Complaints
repairpal.com · Complaint aggregator · damper pulley failure caused belts to grind: 2 reports