Symptoms
No symptoms until it fails, which is the problem. Due every 90,000 miles. The water pump is belt-driven, so a weeping pump or coolant crust behind the timing covers is a good reason to do both now.
The fix, step by step
- Remove the fan and shroud, accessory belts and crank pulley, then the timing covers.
- Set the engine to its timing marks and replace the belt, tensioner, idlers and water pump, plus the thermostat and hoses while you're in there.
- Before installing the new belt, compare its tooth count and alignment marks against the old one, because Engine Builder warns that even a half-tooth error means doing the job twice.
- Watch for P0011, P0016, P0018 or P0021 afterward, which can point to timing misalignment.
Tools & part numbers
- Crank pulley holder
- long breaker bar
- torque wrench
- coolant
- belt kit with tensioner, idlers and water pump (OEM or Aisin-type kit)
Where to buy the parts
Aisin timing belt kit with water pump and tensioner, LX 470/GX 470 (TKT-021)CruiserTeq ↗Amazon ↗
Thermostat, 2UZ-FE (90916-03100, the OEM number GXOR lists)CruiserTeq ↗Amazon ↗
Timing belt kits, 2005 GX 470RockAuto ↗Amazon ↗
Coolant (use Toyota Super Long Life or equivalent), 2005 GX 470RockAuto ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Lexus GX 470 parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.