After many months of anguishing over this
project, I just finished replacing six thru hulls and sea cocks on my
boat. They were the old-style Groco's w/the rubberized rotating cylinders. The problem seems to be if not serviced regularly the rubber surface sticks to the
interior of the body of the seacock. When you try to muscle the handle to open/close the valve you break the handle loose from the face of the end of the cylinder. It cannot be reattached, i.e. you're screwed! Groco has very few replacement
parts and they aren't making any new ones. Thus the decision to replace them. They had done a good job for twenty-some years so decided to stay w/Groco. In addition, their tech
service was very helpful. Now, here's the secret for easily removing these babies, which are usually slathered in 5200: buy yourself a "step wrench" to remove the thru hulls. Once they are out the seacock is easy-just break it free from 5200. I got my wrench from Hamilton Marine-approx $35 plus. It is essentially a graduated size cylinder w/a groove on each side. They catch the two "ears" on the inside of
thru hull. A pipe wrench can be applied to the base to turn the step wrench which for me broke the
thru hull free and allowed me to unscrew them from the seacock. I couldn't believe how easy it was!! I too had read about folks grinding off the heads, sawing them off, etc. I was distressed-although I'm pretty proficient w/my 4" grinder. Forget it-get a step wrench! Additional tip. Once you clean all the old 5200 off of the
backing plates recoat them w/epoxy before applying fresh 5200, Sikaflex, etc. Will try to post some pics I took of finished
project. Cptn Happy