Has anyone changed one of these? I have very little room in front of my engine, about an inch, and adjusting the belt is going to be a real treat. I thought maybe I could go at it from the backside of the pump and not loosen the belt.

I also have the 496 mag HO without much room to work. You have to loosen the tensioner on the opposite side lower pulley, then remove the bracket assembly and pulley right near the pump (big bolts). That's the easy part, the part that sucks is getting to the two big hose clamps on the inlet and outlet hoses and then lining them back up to re-install after you have replaced your impeller. Can you take your back seat out? This would really help. The pump comes apart easily once you get it out. I have an exploded diagram of the 496 ho that a merc tech faxed me. It helped quite a bit. I could fax it or e-mail it to you, if you need it. Good luck...

Harper220

Remove the fuel/water seperator assembly. It makes getting to the intake/supply hoses much easier. You definitely want to remove the sea water pump housing and the change the impellar on a bench.

Mine turned out to be easy. I removed the fuel filter and pump, loosened the belt as the book says, removed all bolts out of pump, including the three that hold it on and just pulled the front half of the pump out. I changed the impeller,stuck on a new o-ring and put it back together. I know I spent a lot more time looking at the project than I spent doing it. Mine had 130 hours and 2 years on it and was in good shape. I am getting ready for a vacation and didn't want to take a chance.