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Holding Tank Vent Hose

John Butler

Member II
As you can see in the photo below, the vent hose for the holding tank is attached to a 90 degree downward elbow that routes the vent hose below the intake hose. The vent hose seems to be totally blocked as pumping out creates suction at the deck fitting that doesn’t release once the pump stops. This is not surprising as the hose can easily get filled with holding tank matter if the holding tank fills completely or even if it is mostly full and the boat heals much too starboard.

Although I’d rather a vent hose attachment on the top of the tank, I’m not sure there is clearance for one. However, it seems to me that the vent hose could come out straight from the current attachment point and flex over the intake hose, still clearing the compartment cover. I’m wondering how others have their vent hose configured on the same model boat (1982 E38 with the holding tank under the seat next to the head which is forward of the main salon).

Another question, can someone reassure me that the white plastic fitting holding the elbow to the holding tank is a threaded piece that I should be able to unscrew to remove the elbow? I don’t want to damage the holding tank in trying to fix this problem.

Thanks,
John
1982 E38
Red Rover
 

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rwthomas1

Sustaining Partner
I can't see that particular hose on my boat so the tank must be different. Would it be possible to rotate that 90* fitting so it points aft and up? Then route the vent hose over the top of the tank? Hard to tell from the pic if you have the depth for that.... RT
 

treilley

Sustaining Partner
John, I have the same setup on my E35 with what appears to be the exact same tank. Mine has a hose barb that comes out straight and yes that is a fitting you can unscrew. Also check the vent at the thru hole in the cabinet behind the potty. Mine was clogged there and created the same symptoms.


You will still need to go under the 1.5in hose though. Maybe you can turn the 90 degree barb so that you can route the hose across the top of the tank. There may be just enough room for that. Either way, you will still have a low point when on a stb tack heeling but should clear itself when heeled to port or nearly level.
 

Cory B

Sustaining Member
Looks similar to our fitting as well. I'm sure theres some slight variation in the location of the fittings, but ours manages to go straight and over the intake hose (so no dips to accumulate gunk). It does torque the vent fitting a bit though - maybe cut off off part of the hose barb to allow a better lead?
 
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mherrcat

Contributing Partner
I bought the book "Get Rid of Boat Odors" by Peggie Hall and she makes a good case for larger sized vent hoses. She also suggests that they should be as short as possible and not angle downward or have any sharp bends but always stay as straight and horizontal as possible or rise slightly from the tank to the hull vent.
 

treilley

Sustaining Partner
I upped mine to 5/8" ID but still need to upsize my vent. It is only 1/2" and that is where mine clogged.
 

Rocinante33

Contributing Partner
Our vent fitting, where it exits the hull beneath a small clamshell vent cover, was clogged with rust and gunk. It appear to have been made of steel or iron that rusted. I took off the clamshell cover and reamed it with an old flat bladed screwdriver and it solved my similar problem. One of these days I will replace that fitting, but it's well down the list.
 

Ray Rhode

Member III
John,

Here is a shot of the vent line on Journey. It appears to have the same 90 degree elbow but mine is rotated up and over the top of the "waste in" line. It clears the cover and does not form a trapl

Ray Rhode
S/V Journey
E35-III, #189
 

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John Butler

Member II
It turns out that the blockage was at the vent thru-hull (just as others have reported). I’m pretty sure the vent hose connector at the holding tank is secured with some kind of adhesive. I don’t want to risk damaging the holding tank or the threaded fitting that is presumably attached to it and can’t pivot the elbow to turn it sideways. I considered cutting the 90 degree elbow off the hose barb. However, I’m not confident that I’d get a secure enough connection for the vent hose with the stub that would remain. So for now, after clearing the blockage, I have left the grungy old vent hose in its original configuration.

Thanks for all the input!

John
 
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