Frozen 'Thru hull'

[SteelCruiser]

toilet used to work.
Have pumped nothing through it for two, three years.

Now, the big thru hull its frozen.

I've sprayed with CRC / WD 40.
Tried a big wrench

But I 'm not even certain how to tell ' which way to turn'?

Is there any chance- when trying to get it to turn- of ' breaking it off' and having sea water suddenly pouring in?

[skipmac]

Can't tell from the angle of the first two photos which way is up or down but whichever, it looks like the handle should be pulled towards the direction from where the photo was taken. Look at the base of the stainless handle where it attaches to the body of the seacock. You will see a bit of the handle that sticks out and will not allow the handle to turn one way, just the other.

To free it up will depend on why it's stuck. Could be barnacles growing in it. Could be corroded together. I would get in the water and look inside the thru hull to see what I could see. If that's clear, plug it from the outside, take off the hose and squirt stuff down the inside of the thru hull. An easy way to block the outside is to cover the hole on the outside with a toilet plunger but have a plug ready on the inside in case it comes loose.

By the way, WD40 is not the best stuff to loosen corroded parts. PB Blaster or Kroil are both much better. Be careful with PB Blaster as it will eat seals and some rubber or plastic parts. If the seacock has a nylon ball or seal I think it would be resistant but not sure. Check first.

[dave777]

Had the same problem a couple years ago and got some great advice on this forum.

What worked for me and was easy:

Bought a 3 liter bottle of cheap Cola. Poor it down the tube so the soda rests on the seacock. I happened to let it sit a few days. Some recommended various forms of acid, some diluted. Cola, actually all soda, it some pretty nasty unhealthy stuff. I read on the interweb that some scientists are now saying that the Dinosaurs died off from a huge soda fad, but I digress.

Then I heated the seacock, not the handle, with a heat gun. Not even to very hot. The first attempt it moved, thought I would have to heat it more.

They all work the same direction as a nut, righty tighty, lefty loosey. When it's perpendicular to the hose, it's closed. When it's in line with the hose, it's open.

[B_Hunter45]

Try vinegar. should do the trick.

[Don C L]

They can break but the ocean won't come gushing in. My friend had the valve on the engine raw water intake broken halfway open. What he had thought was a cooling flow problem in the engine was the valve not fully open.
Mine was stuck the other day. (Mine are all bronze) I let a good deal of boiling hot water down the drain slowly. That got it moving. Maybe boiling hot vinegar is even better! If that didn't do it I'd add the heat gun to warm it up too.