Holding Tank Fittings

[divert00]

I’m sure this has been asked, but I can’t seem to find it. 1986 63 MY. The hose nipple on the holding tank vent has corroded off right at the threaded elbow that comes out of the top of the holding tank. This elbow is a bronze male (tank end) to female (hose end). It looks to be approximately a 1” to 1.5” increase in diameter.I’ll need to remove this elbow and replace. It appears it is threaded in to a bronze plate that is fiberglassed in to the top of the holding tank.
In theory, I should be able to unthread this elbow from the holding tank. Is this a a correct interpretation of the construction and any tips for removing this 36 year old fitting?

John McCarley
Water Colors
Wrightsville Beach NC

 

[SKYCHENEY]

You are correct. It should unscrew from the top plate.

 

[q240z]

...any tips for removing this 36 year old fitting?

Pro tip #1: Don't mess it up.

I would advise replacing with plastic fittings. Sorry. I wish I had more to offer.

 

[dar636]

Just clean up the threads in the tank top reducers and install a new plastic vent elbow. I wouldn't mess with pulling the reducers - the vent line doesn't need to be that large in diameter. See pic-

 

[Captain Ralph]

Pro tip #1: Don't mess it up.

I would advise replacing with plastic fittings. Sorry. I wish I had more to offer.

If possible, go with the Marelon plastic fittings. Not as fragile now or years to come.

 

[divert00]

Thanks. Hopefully, removing the existing elbow will not be too difficult. John.

 

[jmooney]

I replaced my 5/8 vent line with a one inch hose . Just in case I stumble across a pump out station that really works well .

 

[Captain Ralph]

I replaced my 5/8 vent line with a one inch hose . Just in case I stumble across a pump out station that really works well .

Yes, You need good vents when getting pumped out.
I have witnessed lots of dockside issues with odor filters clogged and folk are wondering why and how that happens,,, HA.

I thought Hatt vents were already 1 or 1.25 inch hose.

 

[jmooney]

Yes, You need good vents when getting pumped out.
I have witnessed lots of dockside issues with odor filters clogged and folk are wondering why and how that happens,,, HA.

I thought Hatt vents were already 1 or 1.25 inch hose.

. They probably were , but when I got my boat the holding tank was converted to a fuel tank and a 5/8 fuel hose was used as the vent and it was relocated to a high location. I put the one inch vent hose back down near the water line .

 

[firbanks]

My holding tank fittings are directly below my fwd generator (my holding tank is the farthest fwd tank - between the stringers) and are difficult to reach. If I ever pull the genset I plan to replace the vent elbow with at least 1” - it is 5/8” now. That will help with pumpout and allow more airflow to the bugs in the tank.

 

[pmurphy]

I have the same model boat and the same exact problem. The difficulty in removing that fitting is that is sits down under the plan of the floor and is surrounded by other fittings that are in the way. I think the only was to get if out is to somehow turn it from above. That won't provide a lot of leverage opportunity though. Regrettably, I've made a temporary repair to mine using duct tape!!

 

[rwaldrop13]

No longer an issue since the boat is gone (but not forgotten) for me. However I never did figure out why my holding tank vent line was continually blowing crud up into the vent filter which was mounted about a foot below the on-deck pump out fitting. I had backwashed the tank numerous times, pulled the cap and washed it, never got the level indicator working (because there was a revision to the midship stairs that made it inaccessible). But without fail every time I pulled the vent filter it was clogged, and that was getting really expensive. I was actually pumping out 2x/week since we had at-slip DIY pumpouts available, with no success. It was a headscratcher for older more experienced hands than me as well. I had replaced the hose, and backwashed down the vent line to ensure it was clear, washed the tank, tried a couple of different "digesters" in the tank to reduce buildup but no success. Needless to say, when they lifted the remainder of the hull I was grateful that tank was still intact...

 

[divert00]

Pmurphy, I removed the nearby hoses and pump out fitting( large pipe wrench and cheater bar). Used heat on vent elbow and large pipe wrench. Elbow broke off flush leaving the male nipple in the tank. Well, #$&*@! Used a hacksaw blade, by hand, to carefully cut remaining nipple on opposite sides without cutting in to the female sidewalls.
Used hammer and punch to gently tap each half loose and extract with needle nose pliers. Replace with nylon plumbing fittings. A bear to get in and out of behind the generator, so I camped there, while my wife was tool gopher.

John McCarley