Resources on Wakeworld have been fantastic and allowed me to gather the stones needed to try this. Thanks to Sparky Jay for taking the lead and putting his skills into play. If it is useful to folks, this link below shows the video of the entire process. Thanks to everybody who posted on this thread and shared their knowledge. This is exactly why I love wakeworld!
Step by Step Video:
2007 Mercruiser 5.7L Black Scorpion in a 2007 Sanger V215
9/16 socket with extension
screwdriver for hose clamps
1.) Empty lockers and remove partitions to access engine.
2.) Remove fuel filter mounting bracket (keep fuel lines attached) to move assembly out of the way to have more room to work. Watch out for the extra “spacing” washer. You’ll need a 9/16 socket and a small extension. There are 3 bolts.
3.) Check serpentine belt tension to get an idea of how tight to return it when done.
4.) Ensure that you have a diagram for the proper setup for the serpentine belt so you can return it properly.
5.) Drop serpentine belt by loosening the passenger side idler wheel – needs a pair of wrenches 5/8 and 5/16
6.) Remove two blue thumbscrew tabs to drain pump. Make sure they still have their little o-ring gaskets. Then, disconnect two main water hoses from water pump by loosening hose clamps.
7.) Unbolt and remove entire pump assembly – the mounting bracket will still be attached to the pump. Two bolts, 9/16.
8.) Working outside the boat now, unbolt the mounting bracket from the pump. Then, open the pump by unbolting the three 10mm bolts on the back of it. Then you’ll see the impeller!
9.) Remove old impeller and o-ring gasket. We used large needle nose pliers to grip it and wiggle it free – took some effort.
10.) Lube new one with dish soap, wrap with zip tie to get the splines all going the right way, get the new impeller half way in, then snip off zip tie and insert the rest of the way. Make sure you get it all the way in (should be flush)
11.) Replace the old o-ring gasket with new one that came with your impeller kit.
12.) Reassemble everything! Two tips: 1.) the spacer washer needs some careful handling to get in place. 2.) To tension the serp. belt, make sure the 5/8 nut is pretty tight, then crank the 5/16 at the end of the post. This will turn the entire assemble on its internal track, raising the idler wheel and tightening the belt tension. When it’s tight enough, crank the 5/8 the rest of the way to lock it in.