How do you change impeller on 5.7l mercruiser?

Answer 1

Please Note I am not a mechanic. I had the same problem and found this answer: Tools and materials required:

Socket wrenches, 9/16th box wrench, torque wrench capable of measuring 10 foot pounds, Loctite for threads, Vaseline Petrolem Jelly, and of course a water pump replacement kit that includes the impeller, plastic housing, stainless steel back plate, two gaskets, and new bolts. Warning: The water pump is below the water line and when the lines to the pump are removed water will pour into the boat. I had my boat out of the water when I changed the impeller. Procedure: Loosen the idler pulley and remove the drive belt. Make note of the way the belt wraps around the various pulleys. Remove the two 9/16th bolts that hold the pump and bracket to the engine. You will now have enough room by pulling the pump out of the front of the engine to get to the two hose clamps on the water hoses. Mark the two hoses so you get them installed correctly. Loosen the two hose clamps and pull the hoses off the pump. I took the pump to my garage so I had access to a vise and wire brush. The wire brush was helpful in cleaning the bolt threads to make it easier to remove them. Mark or make note of proper position of the bracket on the pump. Remove the three nuts holding the bracket to the pump. Remove the 5 bolts holding the plastic pump to the metal end. Lightly coat the inside of the pump housing and the new impeller with the Vaseline. The Vaseline protects the new impeller as it will run dry for a few seconds when first starting the engine. Install the impeller in the new pump housing. Install the smaller gasket around the pump shaft, and install the new wear plate. Install the new gasket on the plastic pump, and then the plastic pump to the front half of the pump. Coat the new bolt threads with Loctite. Install the two shorter bolts and just snug them down. Install the remaining three long bolts after coating with Loctite. Tighten all boats in a cris-cross pattern. I set my torque wrench to 50 inch pounds, tightened all bots then increased the torque setting on the wrench till I reached 110 in. lbs. or just over 9 ft. lbs. Install the mounting bracket to the pump. Hold the heads of the bolts when tightening the nuts on the mounting bracket. Reverse the order of installing the pump back onto the motor. Install the drive belt and set the tension with the idler pulley. Make note in your maintenance log of the date and number of hours on the motor when you changed the impeller. Total time involved was about 2 hours. This is a maintenance that can be handled by most weekend wrench-turners.