Has anyone replaced an impeller yet on the new 502/8.2HO? After looking at it today, there looks to be a lot more to it than my old 496HO. It sits behind the cool fuel module and under a bracket. Just wondering if anyone had a plan of attack, other than the dealer Thank you for any help.

The best advice I can give here is when or if you remove your serpentine belt completely - mark the direction of rotation beforehand and when reinstalling it - install in the same direction if you are reusing the belt and of course make sure it is in good condition.

These pumps internally can come 3 different ways from depending on year and other factors.

1. The housing can have no wear plates installed - meaning backside and front side of impeller
2. The housing can have a impeller backside wear plate installed only.
3. The housing can have both side - wear plates installed and it will take the .030 shorter impeller when front plate is installed. They come together in a kit form from Mercruiser. Make sure you have the correct impeller. Impeller and housing tolerances are very important for priming cooling water, to proper flow and proper volume thru out.

This is how Mercruiser is now offering them as well.

I've changed mine in a twin engine application, get ready for alot of swearing! Lol. Hopefully, your single engine will be easier.

Thank you for the tip on the belt, I wondered if the original direction, but planned on placing it back exactly just in case. I usually find it easier to just remove it and get it out of the way. Until I remove the water pump tomorrow, I am under the impression that I only have one wear plate in the housing, but will be sure to make sure the tolerance is tight. Last thing I need to do is re-do the job if it does not pump well.

When you loosened up the bolts and began to remove the pump, did you have to swing the cool fuel out of the way? When I saw a quick glimpse of the part diagram, it looked like there was some sort of fuel block off with a gasket? Until I get my batteries out of the way, it is tough and take a better look under there. And all this fun doesn't address the possibility of having to flush out any pieces that may be missing off the impeller. I have already found a few that somehow made their way out of my air actuator.

I don't believe I had any wear plates in mine, I didn't have to move anything out of the way. Good luck!

here is version # 2 as I posted above - there is bead needed of silicone to install the backside wear plate. Posting this just to show I know what I am talking about.

Wear plate backside is # 14 in link below

http://www.mercruiserparts.com/Show_...=Seawater+Pump

I didn't doubt you for one moment, thank you so much for the diagram. I am feeling a lot better about this. I will be starting this tomorrow morning, I will post back to let you know how it went. I am glad to hear I don't have to move all that.

Thank you both so much for the information, this was a relatively easy task. I was able to locate all the impeller pieces between the water pump and the oil cooler. The total job took just under 4 hours, mostly due the the flushing of the system. I did discover that I also had no wear plates in the pump, but the housing looked good. Thanks again!