Holding Tank Vent

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KenKrawford
Posts: 614
Joined: Wed Nov 02, 2005 8:54 pm
Location: Atlanta, GA

Holding Tank Vent

Post by KenKrawford »

I was helping a fellow C350 owner this weekend with a holding tank problem. When he goes to pump out, the holding tank is pressurized (no further description in case someone is reading this near meal time) ! I could hear air going through the vent as he pumped out but have to assume that it is at least partially blocked or the tank would not have pressurized. There was nothing obvious in the vent opening on the hull.
Has anyone experienced this?
Ken Krawford
Message Board Moderator
C350 # 351
Lake Lanier, GA
lyle
Posts: 45
Joined: Mon Aug 13, 2007 8:22 am

Re: Holding Tank Vent

Post by lyle »

I have not experienced this in my Catalina 350 but have had the issue on a previous boat. I would guess the vent is probably clogged from previously over filling the holding tank. When this happens the waste has nowhere to go except up the vent line overboard and solids can lodge in the vent line. It is an easy job to change the holding tank vent line - while you are at it change the discharge hose as well - your boat will smell better and the head will flush easier.
Triumph
Posts: 256
Joined: Thu Nov 03, 2005 7:34 am
Location: Tampa, Fl

Re: Holding Tank Vent

Post by Triumph »

I have a problem flushing a large XXX when the holding tank value is closed. I thought that maybe my vent was clogged, so I blue on it from the outside of the boat. Air went in, so now I'm thinking, maybe the impeller on the pump is getting weak. It doesn't work like it used to. I plan to check the vent one more time before starting to look at the pump, and recheck the flushing ability after blowing in the vent.
lyle
Posts: 45
Joined: Mon Aug 13, 2007 8:22 am

Re: Holding Tank Vent

Post by lyle »

When was the joker valve and the discharge hose last changed? This happened to me - when I pulled the discharge hose off and looked at it I realized it was clogged to less than half its diameter. I replaced the hose and joker valve and now you can flush a rubber boot - OK not quite - but the difference is amazing.
Triumph
Posts: 256
Joined: Thu Nov 03, 2005 7:34 am
Location: Tampa, Fl

Re: Holding Tank Vent

Post by Triumph »

I think your suggestion might have worked. I removed the 4 screws holding the discharge hose from the base of the toilet, and removed the choker rubber back flow perventer thingy. It was covered with a calcium type build up, and so was the general area in the hose near it. I cleaned all this off, reinstalled everything, and it seems to work well. I'll test it out for real soon. I do give the system a vinegar bath now and then, but I guess not often enough. I think the Bahamas waters may be a real contributor to this build up.
Triumph
Posts: 256
Joined: Thu Nov 03, 2005 7:34 am
Location: Tampa, Fl

Re: Holding Tank Vent

Post by Triumph »

Update. I had gotten a bunch of shell like crud out from around the choker value, and that end of the hose. It worked pretty good for a dozen flushes, then, back to the old problem. I removed the hose, beat it on the dock, and a shovel full of sandy shell like crud came out. Before I did this, I could hardly blow through it. This did the job, and I too can now flush a boot through it. Problem solved !

The challenging part of his was removing the small panel to get access to the top end of the holding tank. I used a blow dryer to help get the hose off the barb once I had access.
lyle
Posts: 45
Joined: Mon Aug 13, 2007 8:22 am

Re: Holding Tank Vent

Post by lyle »

Any saltwater environment will contribute to the problem. Happens in the Pacific Northwest and the Bahama's. Flushing once a month with vinegar will help but the buildup will still occur over time.
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