Holding Tank Vent

SwiftCloud

GreatGrady Captain
Joined
Mar 22, 2006
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Location
Marblehead MA
Model
Marlin
Hello!

Any idea why Grady used (uses?) a fuel tank screened through-hull for the holding tank vent? Mine keeps getting clogged (I think from the outside) and my holding tank ends up under a lot of pressure! I've confirmed no blockage in the vent between the tank and the through-hull.

I'm looking to replace the through-hull with a standard plastic fitting (no screen). Any cautions / success stories?

Thanks!
 
How do you know it’s getting blocked?
What is blocking it ?
 
SwiftCloud said:
Hello!

Any idea why Grady used (uses?) a fuel tank screened through-hull for the holding tank vent? Mine keeps getting clogged (I think from the outside) and my holding tank ends up under a lot of pressure! I've confirmed no blockage in the vent between the tank and the through-hull.

I'm looking to replace the through-hull with a standard plastic fitting (no screen). Any cautions / success stories?

Thanks!
Probably to keep insects from getting into the system. The possible odors would be attractive to fliess especially
 
Ozz043 said:
How do you know it’s getting blocked?
What is blocking it ?

Extensive pressure buildup in the tank is a clear signal that the vent isn't working. I was able to detach the vent hose from the through-hull and blow air (from a pump, not from my mouth!) easily through the hose, so it must be the through-hull (which is more difficult to reach and test)...

I don't know what is blocking as the hose looks clean. Maybe the screen is subject to a buildup that won't occur when used as a fuel vent b/c the fuel vapors inhibit it (just a speculation).
 
Try squirting with a hoze, it’s probably a spider or something benign
 
Same issue with my 07 Express. I just reached in from the outside with a 90 degree small pick and ripped out the blocked screen. It isn't uncommon for those screens to get gummed up and they don't seem necessary. Never had a bug issue. Once I removed the screen, the unit has worked perfect ever since. Each time I pump out I do so until I hear air rushing in from the vent to assure that nothing has gotten into the line and started to block it.
 
This post got me curious so I checked mine.
The gauze was fine but the brass elbow screwed into the top of the holding tank was totally blocked.
It’s a good 1/4” hole and it was chocked.....
I wondered why I could hear a whistle when pumping it out, whistled because of suction ...

Works a treat now though ... :dance
 
Be careful removing the cap to do a pump out when it's under pressure....ask me how I know! Have added the term "Sh*t Volcano" to my vocabulary.

That poor marina worker took it full force, my brother and I both got "splashed" as well :jaw

Cleaned the vent line, problem solved.
 
Bayhouse said:
Be careful removing the cap to do a pump out when it's under pressure....ask me how I know! Have added the term "Sh*t Volcano" to my vocabulary.

That poor marina worker took it full force, my brother and I both got "splashed" as well :jaw

Cleaned the vent line, problem solved.


Thanks for the laugh and the warning!