Yeah, but the stainless on one side plus the gasket with stainless on the other side is net/net zero. I have been reallly happy with mine. Never had an issue and the impeller rebuilds lasted longer than stock.

The wp sensor on my earlier 496 is on the backing plate (where hoses attach). The Hardin pump still uses the stock backing plate, with an additional plate so the impeller does not use the stock backing plate to seal the impeller.

I just installed a mechanical wp gauge. It reads 29psi at 3500rpm.

I hear you but some boats have no sea strainers and wear / scar the blade area sides of the impeller housing internally. So the drop in S S plates front and back are not repairing the side wear / scars of the housing. That was mainly my point. and I agree the drop in repair S S plates can work 100 % for impeller housings but not all of them.

I have seen housings that look like a die grinder was ran internally on the sides. GEN VII, Jabsco, Johnson impeller housings to name a few

the hardin housing replaces the front section of the Gen VII pump. The back section is still Mercs. Hardin uses a Stainless steel backing plate that goes inbetween the hardin housing and the Merc back section. The WP still mounts in the original merc back section that is still used, when replacing with Hardin S S housing (kit).

$450 and you have to use your used back section. Whhhhaaat? Thats Bullcrap!

I just put a new impeller and plate kit in last week to try to solve the problem. I smear dish soap on the inside of the housing when installing the impeller, and didn't notice any scoring on the housing.

I guess I could swap water pumps between motors to find out if its the pump before I have the boat hauled to check the external stuff.

The only other thing I can think of is that I had the drives off this winter for paint. I had a hard time (by myself) getting the drives back on. I wonder if the square oring could have moved on the install, and it could be sucking air while on plane ?? I should be able to prove or disprove that by looking at the PSI of the pump while increasing the RPMS in neutral to see if it goes past 5.8

The Hardin replacemnet impeller kit comes with a stainless front and rear wear plates. The pump housing itself is stainless which is much harder for wear. It is a nice design. It does use the stock rear plate housing which the hoses are connected to. The impeller does not touch the rear plate using the wear plates.