This week a customer brought his boat in with coolant in the bilge. What we found was on the heat exchanger Mercury uses a large hose clamp to hold the exchanger in place. The bottom hoses don't have hose clamps on them, they just wedge in with rubber grommet's and held by the one large hose clamp. The clamp on his broke and when it got hot and pressure was up combined with bouncing around it would spray coolant out.
I would suggest 496 owners carry a spare large hose clamp and coolant just in case.

There are two hose clamps over the heat exchanger. And yes, they are paramount to operation.

Eric tell them how much a impeller kit is for one

Impeller kit is cheep, the complete pump is 472.89$ and none of the internal parts can be replaced only impeller and o-ring.
New pump comes with
Pully
pump
w/p switch
bracket
The pump we took apart only had 110 hrs and needed to be replaced

$500 clams for a water pump!?!?!!? Man, my old tech 1996 454's are looking better all the time!

Just had the same thing happen to a customer yesterday!

just throw a couple of the big-azz cable ties around the works next to/over the hose clamps for insurance...

then just check'em every now and then.

I did the grommet replacement this spring so I know the area.

Great, ONE more thing to worry about.

just checked mine :

I remember the press releases that GM made saying the 496's had capability to go beyond the 502...right