Stuck seacock

The pics below are of the small (1/2" - 3/4"?) seacock that supplies seawater to my aft head. I have not exercised it for the better part of a year and it now refuses to budge. I could apply mucho leverage to the handle but that way leads to tears.

The plug appears to be tapered. Can I slacken nut "A" about 1/4 turn and tap "axially" with a soft-faced mallet to loosen the plug in its barrel?

A search of the forum suggests that "B" might be a drain. I am not familliar with these - can I replace it with a grease nipple? If so, can I do the replacement with the boat in the water?

At next haul out I will remove and service the seacock properly, but for now I just want the head to work.

If anyone reckognises the make, I would be grateful for a scan of the service manual or whatever literature is available. This is original equipment in a 1984 DeFever.

Thanks in advance for the input.

'B' is a drain to remove water from the tapered plug for winterizing against freezing. Water will be trapped in the taper plug hole otherwise.

Yes, the plug can be removed and a grease nipple used. When the seacock is 'open' pump in some grease. Move the handle to distribute the grease.and open and do it again. The grease fitting should not be left at they are usually steel and will rot away. Do not pump grease when the seacock is closed or you will simply fill the hole. Pump only when the seacock is 'closed'.

I don't recognize the seacock, maybe a Taiwanese unit. Most of the domestics of that age used a removeable handle. I haven't seen them all of course but the ones I had , the handles were removeable.

Loosening the plug nut and tapping may loosen the handle. Leave the nut well onto the shaft. Give it just a small amount of clearance. Once the nut is loose and after a few taps then try turning the handle again.

Be carefull/gentle if doing in the water.

I always make sure I have an appropriate size wood or foam plug at my side when doing this. I had a friend that tapped it and it broke off. Bad corrosion but could not be seen.

Hopefully there is a plug on both sides you can use to lube the seacock.

Yes backing off the nut and a tap of a hammer is std when they freeze.

The commom 1/8 inch size will usually accept a SS grease ( Zerk) fitting from an outboard engine source.

Job done and thanks to all who responded.

A half turn of the nut and a couple of gentle taps was all it took.

A 1/8 x 27 grease nipple fitted. Having the right size pipe tap to clean up the threads was useful. I put the brass screw plug back in when the job was finished. Sadly no hole on the other side Fred, it would have helped - just a stub in the casting where one could have been machined.

I have concluded that pumping grease into an old dry valve probably helps, but it is really not the answer. Removing the core, reseating it with valve grinding paste, lubing it before reassembly and then an occasional pump of grease is the right way to go. I'll do this to all three on the next haul out.

BTW: The piece of bright orange 1/2" PVC pipe is not for leverage! I have one on the handle of each of the small seacocks so I can see at a glance if they are open or closed - it's dark down there. The levers on the larger seacocks (head outlet, engine cooling etc) are yellow and big enough to be seen easily.

The PVC is a good idea. A 120' corporate yacht I was associated with for awhile had the handles of all its seacocks wrapped in reflective tape so they would "glow" in the light from a flashlight.

those tapered designs were far superior to todays ball valves because they could always be loosened .


I had some with rubber taper plugs and big wing nuts to draw up the plug, brilliant idea.

The proper grease cups for seacocks work better than grease gun fittings IMO. Easy to use, just give them a twist, and no clearance issues with getting a grease gun in a perhaps a tight spot.

Buy Aquafax GREASE CUP 1/4 BSP 33mm OD Miscellaneous Engine parts at Marine Megastore Chandlery 15% off orders over £300!*

Darn Bill you are dating yourself. Haven't seen one of those in a long time.

Yeah it's to bad they are so hard to find these days. Perko or Groco used to sell them as I recall. They work great.

Hello Shoalwaters,

I just finished servicing my two engine raw water tapered cone seacocks on our 1974 Grand Banks. I followed the excellent directions from this web site, Compass Marine, Compass Marine How To Articles Photo Gallery by Compass Marine How To at pbase.com

It is a very do able project, especially given the apparent room and access you have. After servicing mine the work smoothly and easily.

Nicely done Shoalwaters. Now we need to talk about that ball valve on a thruhull next to your very nice seacock. I really hate to see that. The threads in the valve don't match the threads on the thruhull and the thruhull can break. I'd like to see a Groco flanged adapter between the valve and thruhull. It solves the mismatched thread problem and protects the thruhull.

I caught that too Parks.


1983 Present 42 Sundeck
Twin Lehman 135's

I think you can find those grease cups at McMaster Carr. I'm sure I've seen them in the cat..

Grease cups would be nice, but this is a small seacock and the thread for attaching nipple or cup is only 1/8" pipe. I am not comfortable with a Christmas tree of adapters.

Parks and Forky: Thanks for the heads-up, I had seen it so often it didn't really register. It is now on the list for next haul. Believe it or not, that was the original w/c outlet; just upstream of the flush water inlet, so the bowl was being flushed with a mixture of . . . well never mind! The new outlet is on the oposite side of the keel.

That 'compass marine' website listed is phenomenal. Great info, and lots of pics.

Read and heed. Good stuff.

One of the best lessons I received as a kid was watching the yard work boat (which was used every day, for 9 months a year) being lifted out of the water after the dual strainer element froze and cracked sinking the boat.

Shut off the sea cocks each and every time you leave the boat. period. It should be a part of the daily routine when boarding the boat. When arriving, open. When departing, close. Simple. Safe.