My Columbia 10.7 was suffering from hardening of the arteries. More specifically, hardening of the seacock. In way of explanation, Groco manufactured a style of seacock (SV Series) that featured a rubber plug in its heart.
The Groco SV series of seacocks was a unique design. Instead of a tapered bronze plug or spherical ball, it had a rubber plug. The horizontal rubber plug had a vertical hole through the center. To operate the valve, a wing nut on the side of the seacock was loosened. This relieved pressure on the rubber plug and allowed the handle to rotate it open or closed. Once in position, the wing nut was tightened, compressing the rubber cylinder and sealing off any leakage. These units were manufactured from 1960 through 1993 and have served faithfully in many installations if properly maintained.
However, when maintenance is deferred and the seacocks aren’t exercised often or maintained, the rubber plug hardens and the seacock becomes harder and harder to operate. In my case, the previous owner had let them go to the point the cooling water inlet seacock seized up to the point the handle broke off. The good news was that it broke off with the seacock open so the engine could be run. The bad news was that the seacock had broken with it in the open position with no way of closing it.
I limped by until the next haul out by simply squeezing the hose closed with a pair of Vice-Grips, not an ideal situation. But I knew I would have to replace the seacock at the next haul out for safety’s sake. As haul out time approached, I began to gather the needed supplies and tools to accomplish the job. The first order of business was purchasing a new seacock, one with a stainless steel ball with Teflon seals, a stainless steel stem and a bronze body.
I chose a Groco model BV750 bronze seacock. In addition to the stainless steel ball and stem, it had PTFE (Teflon) seals and is serviceable while installed. The triangular base offered different mounting holes than the old seacock, which turned out to be a good thing. There are two drain plugs and a provision for attaching the grounding wire.
While going through my parts boxes gathering supplies, I came across a flush valve setup I had done a magazine test on years before. The system was designed for an I/O unit on a powerboat but had features I liked. Primarily, it featured a quick disconnect fitting and associated ball valve that allowed for easy introduction of antifreeze in the engine. You simply connected a hose to the quick disconnect fitting and dropped it in a bucket of antifreeze.
It also came with a length of hose with a quick disconnect fitting at one end and a strainer at the other. This could be dropped into the bilge and the valves configured to allow the engine cooling pump to act as an emergency bilge pump. With a little repurposing, I adapted that setup to my new seacock installation.
With all the necessary parts on hand, it was time to get started. Once the boat was hauled, the first task would be to remove the thru-hull from the seacock. Now, this particular thru-hull had been in place since the boat was built back in 1978. I figured it was well and truly stuck in place and wasn’t looking forward to having to remove it. To ease my task, I purchased a thru-hull removal tool. This was a cast iron fitting that was stepped and notched to fit anything from a 1/2” to a 1-1/2” thru-hull.
I figured I would need all the help I could get so I used a pipe wrench on the tool with a four-foot pipe as a breaker bar on the pipe wrench handle. To my utter surprise, the thru-hull backed slowly but surely out of the seacock. The butyl sealant applied all those years ago was still sealing yet still pliable. In fact, I don’t think I even needed the breaker bar,
With the thru-hull removed, it was time for the next surprise. I had purchased a new thru-hull to go along with the new seacock as I thought I might have to cut the old thru-hull out. My thru-hulls are all of the flush, countersunk style. Guess what? Modern thru-hulls have a much smaller head than older ones. If I would have had to cut the old one out, I would have had to fill in and patch the old hole to fit the new thru-hull. Luckily, the old one was in perfect shape and could be reused.
The first step in assembling the new seacock and associated plumbing was to add a bronze tee to the top of the seacock. I fitted one leg of the tee with a hose barb for the connection to the engine cooling water intake. The other leg had, first of all, a ball valve then the quick disconnect fitting. Actually, it was a bit more complicated than that as I had to use some creativity and additional bronze fittings to get the various connections headed in the right direction. I used Teflon plumbers tape on all connections.
The original seacock was installed on a plywood donut epoxied in place. I had planned on replacing that donut along with the seacock. On inspection, the donut was as sound and as solid as the day it was installed, a further sign that no leakage had ever occurred. One less job to accomplish.
I found a reputable supplier of marine butyl sealant online (www.pbase.com/mainecruising/butyl_tape) and purchased more than enough for the job. I applied a layer of the butyl sealant on the thru-hull with a bead of it around the base of the threaded section. I then screwed the thru-hull into the seacock and slowly tightened it. The sealant will slowly flow into place so I retightened the fitting over the next day or so, scraping off the excess sealant that oozed out.
While I was at it, I decided to replace the hose from the seacock to the engine as it was also original to the boat. I pulled it out to get a measurement for the needed length of new hose. BIG MISTAKE! I should have bought more hose than needed and taped the end of the new hose to the old one so I could pull it through the various limber and access holes. I probably spent more time fishing that new hose in place than replacing the seacock. Lesson learned.
Operation of the new seacock is simple. Normally, the quick disconnect ball valve is kept closed and just the normal seacock opened for cooling water and closed when I leave the boat. To winterize the engine, I close the seacock and open the ball valve. A hose from the quick disconnect is placed in the antifreeze and the engine started. Normal cooling pump operation will pull the antifreeze through the engine. By switching the antifreeze hose with the strainer equipped hose, I can use the engine cooling pump as an emergency bilge pump.
So I now have a new seacock for my engine cooling water intake. In addition, I have an easy way to winterize the engine with antifreeze and the possibility of using the engine cooling pump as an emergency bilge pump if needed. As long as I regularly exercise and maintain the seacock, it should last as long as the original, maybe longer.
With the engine cooling seacock replaced, that only leaves the galley sink, the head sink and the head overboard discharge seacocks to be replaced, Whew!