How to Replace the Impeller or the Water Pump in a 1974 85 Horse Johnson Outboard
- 1). Disconnect the negative battery cable and remove the engine cover. Unscrew the shift rod, located under the carburetor.
- 2). Remove the lower unit gear case covering, which is held in with four bolts, plus two additional bolts under the cavitation plate.
- 3). Remove the four bolts that secure the water pump head, and keep track of which bolt goes in which hole -- two of them are longer than the others. Pull the water pump cover off, using a small hammer to carefully tap it loose if it is stuck. You should see the impeller, the plastic part with six fins. Note the direction in which the fins are bent; you will need to bend the new impeller's fins in the same direction.
- 4). Pull the impeller out with a pair of needle nose pliers. Pick out any broken pieces in the water pump housing.
- 5). Lubricate the new impeller with dish soap and slide it over the shaft. Bend the fins in the same direction as the old ones, align the impeller's keyway over the shaft's key and slide it in place.
- 6). Replace the water pump head, making sure the water hose is properly aligned. Reinstall the gear case housing, and securely tighten the bolts. Replace the shift rod screw and reconnect the battery cable.
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