I need to replace the riser gaskets as they just started leaking, also my captians call is leaking out of the butterfly. Is the riser gasket for the 502 all the same or different per version of 502? Mine is in a 98 powerquest serial number **173702. What is the best place to buy riser gaskets and corsa parts? Is there anything else I should do while in there? Obviously will check for signs of water etc, but in the down pipe, is there butterflies to replace etc? Thanks

There are bunch of different kinds of 502 from mercury alone, go to mercruiserparts.com and find the part number that matches your engine serial number.
As for the captains call, a small leak out the transom with them closed is normal.
There are flappers in the Y pipe that might need replacing, depends.

Thanks, the corsa leaking out of the transom wouldnt be a concern. Mine are leaking from the solenoids/butterflys so in turn leaking into the bilge

I would contact corsa marine about that