Lubing Seacock

In preparation for our trip north to CT, Magic is being hauled on Monday for routine bottom painting and inspection. Our main engine(s) seacocks are operable but getting stiff. I'm thinking that with the boat out of the water, I can simply apply grease to the rubber cone thru the top of the strainer and apply grease up through the bottom of the thru hull as well. Is it necessary to disassemble the whole contraption? It would also be easy to flush the seacock with fresh water and work it open and closed before greasing.

Interested your thoughts. Thanks, Howard

Greetings,
Mr. hm. On one of our previous hauls I disassembled all 15 seacocks/valves, lapped them, greased and reassembled. MY reasoning for doing this was 1) My main engine seacocks were VERY stiff and 2) I had no idea when they had been done last or would be done again. All good thus far after 5 years.

HM, what kind of seacock do you have? You mentioned rubber cones, that suggests old Groco seacocks. There are three different types of seacocks, ball valve, taper cone, and expanding rubber plug. All require different maintenance.

AFAIK only the tapered cone type of seacock can benefit from greasing. See Servicing Tapered Cone Seacocks Photo Gallery by Compass Marine How To at pbase.com for the maintenance procedure.

Other types like ball valve types have a stainless steel ball against a plastic seat and grease doesn't do much. Opening and closing a dozen times should help those types.

David

HopCar said:

HM, what kind of seacock do you have? You mentioned rubber cones, that suggests old Groco seacocks. There are three different types of seacocks, ball valve, taper cone, and expanding rubber plug. All require different maintenance.

Click to expand...

HopCar,
Yes they are 1995/1996 vintage Groco. They have a handle at one end to open and close the seacock and a handle on the other end to compress and tighten/expand the rubber piece inside.

I would take them apart. It's the only way to know the condition of the rubber.

I shoot WD-40 into them and work them a few times. This has worked for over 20 years.

Hm, the old Groco seacocks develop a bulge in the rubber plug where it lines up with the opening. Remove the rubber plug, sand the bulge down, put a little silicone grease on it, and reassemble. Figure ten to fifteen minutes per seacock.
Eventually the rubber will deteriorate and you'll need to replace the seacocks as parts are no longer available.

HopCar said:

Hm, the old Groco seacocks develop a bulge in the rubber plug where it lines up with the opening. Remove the rubber plug, sand the bulge down, put a little silicone grease on it, and reassemble. Figure ten to fifteen minutes per seacock.
Eventually the rubber will deteriorate and you'll need to replace the seacocks as parts are no longer available.

Click to expand...

The seacocks are in the open position virtually all the time except when I am cleaning the strainers. Do you think i will find a bulge? Parts are no longer available? Wish you didn't say that.

You might find a little bulge where the rubber expanded into the drain holes. Maybe the rubber has gotten hard in the expanded position and doesn't shrink when you loosen the the compression screw. Take one apart and see if you can figure it out. As I recall you only have to remove two bolts to remove the rubber plug.

I wish I could tell you how long they'll last. Might still last a long time. The common failure mode starts with them sticking and when you try to force it, the shaft turns but not the rubber. The other failure is that eventually the rubber won't expand enough and the dripping annoys you enough to replace them.

Don't worry, replacing seacocks isn't as bad as it sounds. Anyway, yours could last several more years.

The trick with the rubber units is to well loosen the T handle , taking all the load off the rubber.

NEVER operate the open close handle with out first freeing the rubber a good bunch.

I have these on my boat and Hopcar is right; if the lever isn't exercised regularly the rubber plug tends to expand under pressure into the cavities of the bronze housing. It takes a set and will totally lock the plug in place.

You can try removing the drain plug and shooting some silicone grease in. That helped loosen up a couple of mine. If it still sticks or won't turn at all, you can remove the two screws on the cover plate. Working the lever back and forth gradually with some silicone spray, I was able to get a badly stuck plug out and sanded it enough to get it working again. That said, I still plan to replace all of mine.