Water Pump: Inspection

Check the water pump bearing for smooth rotation.
Check the water pump pulley for abnormalities.
Using a dial gauge, measure the impeller runout in thrust direction while rotating the pulley.
"Thrust" runout limit:
1. 0.5 mm (0.020 in)
Fig 1: Measuring Impeller Run Out
Courtesy of SUBARU OF AMERICA, INC.
Check the clearance between impeller and pump case.
Clearance between impeller and pump case:
1. Standard
  1. 0.5 - 0.7 mm (0.020 - 0.028 in)
2. Limit
  1. 1.0 mm (0.039 in)
Fig 2: Checking Clearance Between Impeller At Pump Case
Courtesy of SUBARU OF AMERICA, INC.
After water pump installation, check the pulley shaft for engine coolant leaks. If leaks are noted, replace the water pump assembly.