WrxBuild.com Service & Build Log

SEC 04 · Procedure

EJ Timing Belt & Water Pump, Marks Explained

The 105k service on any EJ-powered WRX/STI: belt, pump, tensioner, idlers, and getting all the cam marks lined up without panic.

Procedure

  1. Remove the accessory belts, crank pulley, and timing covers. If the crank bolt fights you, a starter-bump with the socket braced against the frame rail breaks it loose — breaker bar clear of your body.
  2. Set the engine to timing position: the crank mark and all four cam marks aligned to their notches. Mark the old belt against every pulley with a paint pen before removal as a sanity reference.
  3. Compress the new hydraulic tensioner slowly in a vise over several minutes and pin it. Cranking it fast damages the internal seal.
  4. Replace the water pump and thermostat with OEM parts — aftermarket pumps and thermostats are the most common cause of post-job overheating on EJs.
  5. Route the new belt in the factory order, keeping tension on the non-tensioner side. Double-check every mark; the DOHC EJ has left and right cam pairs that love to slip a tooth.
  6. Pull the tensioner pin, rotate the crank two full revolutions by hand, and verify every mark returns home. If anything is off a tooth, reset it now — valves meet pistons on an interference EJ.
  7. Reassemble covers and pulleys, torque the crank bolt to spec, refill and burp the cooling system nose-up through two fan cycles.

Work at your own risk. Torque values and procedures vary by vehicle — always confirm against the factory service manual for your exact model.

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