Hi there, I'm looking for some advice. I'm going to change the heat exchanger pencil zinc on my universal M25. I closed the raw water intake valve and then unscrewed the socket to replace the zinc on the heat exchanger, I was expecting some water to flow out, but it just kept coming... the valve is defiantly closed or so I think.. I'm a little concerned. Any advice? Thank you!
Catalina 30 - Replacing Heat Exchanger Zinc (issues with too much water after closing thru-hull).
- Thread starter ChrisVR1994
- Start date
There's a lot of water in that system, don't be surprised. Look at how long the hose run is from the thru hull to the rw pump to the HX, and it's most likely a 5/8" hose.
Two ways to deal with it: 1) If you want to assure your thru hull is closed, just wait until the water stops. 2) Don't worry and just replace the zinc.
Good luck, either way not an issue.
Two ways to deal with it: 1) If you want to assure your thru hull is closed, just wait until the water stops. 2) Don't worry and just replace the zinc.
Good luck, either way not an issue.
On my 3" heat exchanger, about 3 cups of water drains when I open the zinc nut. How much water have you seen comming out? I capture the water in a 1gallon zip bag, some spills in the engine bilge which I drain out using a syringe. You can also view the water strainer to see if it is emptying out. If not then your through hull valve is not closed.
Thanks Joe. more than that, at least 3 gallons so far. i have the valve closed but maybe im missing something
If the flow of water doesn’t prevent you from removing the old zinc and getting the new one screwed in, I would just do it.
But I would also mark that valve for replacement at your next haulout.
Generally, if the handle is “in line” with the valve body, it should be open, and if the handle is perpendicular to the valve body, it should be closed. I suppose someone could change the handle orientation, but not typical.
And I would get in the habit of closing all of the thru-hulls when you are not at the boat. Bad clamps, rotted hoses and the like have sunk too many boats. Then you will know if they are open or closed.
Good luck with the zinc.
Greg
But I would also mark that valve for replacement at your next haulout.
Generally, if the handle is “in line” with the valve body, it should be open, and if the handle is perpendicular to the valve body, it should be closed. I suppose someone could change the handle orientation, but not typical.
And I would get in the habit of closing all of the thru-hulls when you are not at the boat. Bad clamps, rotted hoses and the like have sunk too many boats. Then you will know if they are open or closed.
Good luck with the zinc.
Greg
Chris.
Your challenge is an interesting one. What you report implies that there is a siphon occurring.
Is the opening for the zinc below the water line?
I wonder do you have a PSS dripless shaft seal?
Is there a hose connected to the collar to let water flow from the HE to the collar and out the shaft log?
Your challenge is an interesting one. What you report implies that there is a siphon occurring.
Is the opening for the zinc below the water line?
I wonder do you have a PSS dripless shaft seal?
Is there a hose connected to the collar to let water flow from the HE to the collar and out the shaft log?
There should be two seperate devises that stop the flow of sea water. Your thru-hull valve should stop the flow. If it is the original gate valve, it is very possible that it is not sealing. Even if your thru-hull does not seal you still should not have any seawater that free flows into the boat because the raw water pump is a positive displacement pump which means that the only way that water should pass through it is by rotation of the pump. no turn, no water. It sounds like you could have a couple of problems.
Thank you Hayden, I'll double check everything, I appreciate your expertise.
If there isn't much left of the zinc and it looks rough ( as opposed to smooth and conical) you should remove the end cap and remove any zinc chunks that might be in there. And, if you remove one end cap, remove the other and rod out the exchanger. A .177 caliber bore cleaner works well.
Given this fact, the thru hull valve does not appear to be completely closing. Time to replace it. IMHO.
Does your C30 have a quarter turn ball valve or a gate valve for the thru-hull? If it is a gate valve, they should be replaced along with the pipe that comes thru the hull. I am not sure when Catalina started installing real thru-hulls but know it was sometime after 1980 and before 1988. My 1980 C25 had brass pipe nipples that were put through holes in the hull and held in place with a bound of resin with chopped strand matt. Mine fell out just after I launched one year. I was very fortunate that the trailer was still on the ramp so that I could put it back on and drain the water out.
Thank you all for the insight. Just to follow up, the valve is indeed under the waterline and here are some images of both the valve and the heat exchanger
Attachments
IF the valve can be closed completely, consider removing the hose from the top and add on a "T". On the top of the T place a threaded plug. Plumb the hose through the side of the T. This will give you the ability to rod out the intake. Marine life loves to set up housekeeping in the intakes and valve bodies.
Should you note an increase in engine temp and the raw water discharge is less, there is a good possibility that there is an occlusion in the intake. With the valve closed, remove the plug and then open the valve. you should experience a fountain. Anything less is indicative of a blockage. A small wooden dowel pushed down thru until a fountain occurs will do the trick. There should also be a strainer immediately off the side T before the intake hose.
Should you note an increase in engine temp and the raw water discharge is less, there is a good possibility that there is an occlusion in the intake. With the valve closed, remove the plug and then open the valve. you should experience a fountain. Anything less is indicative of a blockage. A small wooden dowel pushed down thru until a fountain occurs will do the trick. There should also be a strainer immediately off the side T before the intake hose.
That's an RC Marine valve, from the 80's. ForeSpar bought them and redesigned the product in the 90's.
If the handle rotates firmly from the open to the 90 degree stop position it should be OK. But it might be a time to move forward in technology.
We changed all of our OEM RCMarine thru hull valves out to the better-design ForeSpar 93 series seacocks in the 90's. Good product with no worries about electrolysis.
If the handle rotates firmly from the open to the 90 degree stop position it should be OK. But it might be a time to move forward in technology.
We changed all of our OEM RCMarine thru hull valves out to the better-design ForeSpar 93 series seacocks in the 90's. Good product with no worries about electrolysis.