[C320-list] Marelon Parts

[Dave Hupe]

 Sara-
The kit of O-rings that Forespar sent to me deal only with correcting seeps that may occur just around the valve shutoff handle.  That would not resolve a problem (If any) associated with the valve "ball" itself.  
You mentioned "monthly maintenance" that you do involving rotating the valves.   This is good, but lubrication also is periodically recommended.  For instance, when I have my boat on the hard, I use a small brush and reach upward from outside and apply a waterproof Teflon grease to the "ball" and then work the valve.  There are other recommendations that suggest also doing the same from inside the boat to get the entire "ball" lubricated.  I have not done this because on most of my valves it would require pulling off the associated hose to be able to get grease onto the "ball" at the outlet end of the valve.  To get around some of this, there is a liquid lubricant available that can be poured into your galley and head sink drains that would flow down into those valves (that you then would close/open to lubricate the "ball"). If your boat is on the hard, you can do this and have someone catch the lubricant draining out one of those thru-hulls and reuse the liquid lubricant in other such sink drain. 
I know from experience that even a new valve is "stiff" to work as you described.  So, even with routine lubrication the valves won't necessarily work as easily as you may think. You can loosen slightly the 4 top screws holding the valve body together and it WILL work more easily, but Forespar warns that such activity can cause the valve body to leak,  so not recommended !
Based upon your explanation about the valve feeding your raw water pump, I agree it may be advisable to replace that valve and flush thru-hull assembly.  I believe the assembly would be either of these 2 from Catalina Direct (the only difference being if you have a straight outlet from the valve or a 90 degree elbow:
https://www.catalinadirect.com/shop-by-boat/other-catalinas/interior/plumbing/valves-thru-hulls/seacock-34quot-flush-90-degree-hose-barb/

https://www.catalinadirect.com/shop-by-boat/other-catalinas/interior/plumbing/valves-thru-hulls/seacock-34quot-flush-straight-hose-barb/

Dave Hupe
1994 C320 (#32)
Holland, MI