How to Change a Sea Water Impeller on a 350 Mag Motor

You should replace the sea water impeller in your 350 Mag every season. It pulls in water to cool the engine. A worn impeller cannot pull the proper amount of water, which causes the engine to overheat. Impellers are fairly inexpensive to buy at your local boat shop. You will need to verify the year and outdrive model of your engine to ensure that you buy the correct impeller.

• 1

  Place the throttle in the forward position.

• 2

  Place a container under the drain screw on the bottom of the outdrive near the skeg. Remove the drain screw with a flathead screwdriver and allow the gear lube to drain.

• 3

  Remove the bolts that secure the lower unit of the outdrive to the upper unit with a wrench. These bolts are located in the center of the outdrive between the two fins. There are three bolts on each side.

• 4

  Remove the lower unit of the outdrive carefully by lowering it from the upper unit. The drive shaft spindle will be attached to the lower unit; use extreme caution to avoid damaging the gears.

• 5

  Locate and remove the four screws that secure the impeller housing to the outdrive with a wrench. The impeller housing mounts to the top of the lower unit. The drive shaft spindle extends out of the impeller housing.

• 6

  Pull the impeller housing toward you and off of the drive shaft spindle.

• 7

  Pull the impeller from the drive shaft with your hands. Install the new impeller on the drive shaft spindle and slide it down toward the outdrive. Replace the impeller housing assembly and install the four bolts. Tighten them with a wrench.

• 8

  Reinstall the lower unit of the drive shaft onto the upper unit. Use caution to avoid damaging the gears as you raise it up to the upper unit. Align the mounting holes and install the bolts. Thread the nuts on the opposite side and tighten them with a wrench.

• 9

  Refill the gear lube by screwing the hose connector that came with gear lube onto the drain plug. Remove the vent screw on the top of the outdrive with a flathead screwdriver. The vent screw is near the square section of the outdrive on the side.

• 10

  Pump gear lube into the outdrive until it seeps out of the vent hole. Remove the hose connector and install the drain plug. Tighten the drain plug and the vent screw with a flathead screwdriver.