How to: Water Pump Replacement CRF 450
¼” drive Ratchet
¼” drive extension
Inch pound Torque wrench
Blind bearing puller
Seal / bearing driver
Engine assembly lube
Step one: Drain transmission fluid from transmission drain bolt and drain coolant from lower water pump housing bolt.
Step two: Using some flat cardboard cut from a cardboard box, make a template of the bolt pattern of the water pump housing, the clutch cover and the right side crankcase cover. Punch holes in it to receive the bolts.
Step three: Remove bolts from the water pump housing. Remove housing to expose the impeller.
Step four: Remove impeller using a 10mm socket. It is a standard thread so nothing special needs to be done. ( the 250’s are a reverse thread…)
Step five: Remove clutch cover using an 8mm socket. Use a criss-cross pattern to avoid warpage. Place bolts in their respective spots on your cardboard template.
Step six: Remove right side crankcase cover using an 8mm socket. Use a criss-cross pattern to avoid warpage.
Place bolts in their respective spots on your cardboard template.
Step seven: Remove water pump shaft by pulling straight up on it from the backside.
Note the grooving on the shaft. Simply replacing seals at this point will cause the new seals to fail rapidly. This shaft needs replacement.
Step eight: Using a seal puller, remove the water seal from the front side of the water pump housing.
Step nine: Using a blind bearing puller, remove the bearing from the backside of the water pump housing.
Step ten: Using the seal puller, remove the oil seal from the backside of the water pump housing.
Step eleven: Thoroughly clean the rightside crankcase cover of any foreign debris before any reassembly occurs. Lubricate the new oil seal (P/N# 91201-965-000) with assembly lube before installing.
Step twelve: Install new oil seal into the backside of the water pump housing. Install the seal spring side up using a seal driver of the appropriate size.
Make sure it seats all the way down against the boss.
Step thirteen: Before installing the new bearing ( P/N# 91001-KA4-003 ), place it in the freezer for an hour. Put some assembly lube around the edges of the casting to facilitate the installation of the bearing. Drive the bearing in until it seats using a bearing driver.
Step fourteen: Install the new water seal ( P/N# 91211-MEN-A01 ) from the front side of the water pump housing. Liberally coat with assembly lube and install with the spring side up using a seal driver.
Step fifteen: Liberally coat the new water pump shaft ( P/N# 19241-MEB-670 ) with assembly lube and install from the backside of the crankcase cover.
Step sixteen: If you have the new style impeller (hole drilled in it) skip this step. Drill a 1/8” hole, 3/8” from the edge in between the blades. This will help to equalize pressure on both sides and prevent cavitation.
Step seventeen: Reinstall right side case cover. Use a new gasket if the original was damaged in the removal process. A new gasket should have no sealant applied, only a light coat of oil. Torque bolts to 84 in/lbs using a quality torque wrench or snug plus 1/8th turn.
Step eighteen: Install impeller and copper washer on water pump shaft. Torque to 108 in/lbs (9ft/lbs or 12 N/m).
Step nineteen: Install water pump housing cover. Use a new o-ring (P/N # 19226-MEB-670 ). Torque bolts to 84 in/lbs ( 7 ft/lbs or 9.9 N/m ).
Step twenty: Install clutch cover. Torque bolts to 84 in/lbs ( 7 ft/lbs or 9.9 N/m ).
Refill transmission with fluid and coolant system with coolant.