Holding Tank Vent fittings

[Dan Mapes]

Hi Gang, and Happy New Year!

Santa dropped a good one under our tree, or shall I say he put a whopper in the tank. We pumped out recently without issue. However, the tank tender started to read oddly right away. It maxed out with one or two pumps. So I pulled the tender tube from the fitting on top of the tank and this clear ectoplasmic goo seeped out and wow did it stink! Ok the tank is pressurized. A quick 2 second hit hit on the macerator stopped the flow out of the tank tender sender fitting that mounts the tube into the tank. No neighbors around so it’s all good at this point.

Our holding tank vent line plugged. I was hoping that it would be the vent carbon filter, but no, it’s fine. So is the line over the side from the vent filter. As it turns out the line into the tank is clear. I have chased it with a greenlee wire snake. And yes, I put some saran wrap on the end and tried to blow into the tank. Has anyone pulled the fitting out of the tank and what’s in there? I currently have the hose to the tank outlet full of west marine (blue) head treatment standing on end in the closet hoping it will seep through what ever has done this deed.

Happy New Year!!! I hope Santa was better to everyone else!

[bobk]

Dan, Not sure I understand.... the entire length of hose is clear? If so, pull it off and try to snake into the pipe fitting. If you can't break through, simply replace the fitting. It should not go beyond the plate it is screwed into.

Bobk

[Pascal]

I never tightened the pump out cap, always leave it loose as a back up vent in case the vent of the charcoal filter gets clogged. Saves a lot if headache!!

When pumping out (pump out or overboard) I always open one of the vacuflush ball valve so that if the vent clogs the tank won't collapse (plastic tanks)

On my early boat, the vent fitting is just a basic round thru hull. If yours has one if dem fancy thingy with screen it may be clogged

[the kuz]

Dan, not sure exactly what your isssue is, but will share what I found when our tank was acting up 2 years ago and would not pump out as it should. First thought was that the pvc sleave I put into the pick up tube had somehow come loose but that was not the problem. After taking off the vent line at the tank fitting, discovered that the line was clear out to the overflow/vent, but plugged inside the fitting/tank. The plate that holds the fitting for the pumpout, vent and waste hoses was pretty corroded as were all the screws that held it in place. I tried to remove the top end fitting, but as expected lots of pull with a big wrench started to tear the entire mounting plate out. Ended up taking the entire plate/fitting assembly off the tank top. The pump out and waste line attach fittings were partly clogged and the vent and fitting for the tank full indicator were completely clogged.

Took a good bit of cleaning and several acid soaks to get the hard deposits out of the elbows/fittings and get everything back to bare metal. Drilling out all of the broken screws from the tank top was a smelly and nasty/time consuming job. Re-seated mounting plate with 4200 and used SS self tapping screws to attach back to tank top. Re attached all hoses - has worked fine for the last 2 years (even the 3/4 full indicator). Took 33 years to clog up the first time, but still there must be some way to stop/remove the build up short of a complete teardown.

Just posted this to let all know that tank fittings can totally clog with hard deposits that are difficult to remove/clear. Tank won't pump out completely/right once that happens.

Regards, Bob K

[captainwjm]

[QUOTE=Pascal;

When pumping out (pump out or overboard) I always open one of the vacuflush ball valve so that if the vent clogs the tank won't collapse (plastic tanks)
d[/QUOTE]

I assume you turn the VUF off, and, what, prop the flush lever open?

[Dan Mapes]

Ok, what I do know is the vent fitting was plugged. What I do not know is exactly where, but I am presuming just inside the tank under the plate.
I was able to connect a hose to the vent line after I detached it from the carbon filter I installed. About 40 PSI later it blew through the clog and we are back in business. I did not want to pull the hose off at the fitting because it is difficult to reach, and it was full of west marine blue in an attempt to dissolve what ever was jamming up the fitting.
I did not want to get into surgery at this point since we are in the Bahamas at Sea Spray.

Here is a link to some photos that show the vent filter I conjured up using KISS mentality. I looked at the stuff available and thought wow, that quarter inch line into the filter MIGHT handle a good fart let alone our tank. I use some air conditioner carbon filter cut into strips and rolled up to keep the charcoal from moving out side the tubes.

http://s252.beta.photobucket.com/use...%20Vent%20Line

I would have answered sooner but the gas in the dink turned a nice milky white color and I had to dump it and clean the carb today. NEVER put water sorb into the dink tank. It gets past the water separator filter and fails to fire in the outboard.