Oh dear air vent, why doth thou leak?????

[halliealdrich]

It started a few years ago when my boat destroyed its tether and ran aground, resting on the diesel intake side. I noticed some leakage and cleaned it up. A consult with help said that sometimes the diesel will flow out of air vent at that extreme angle, and apparently elsewhere since there was diesel in the bilge, five absorbency mats-worth. Fast forward a year, after joining the yacht club, where I had access to dockside workspace! I added diesel via the intake port, and in about 30 seconds the diesel started spitting out the air vent.

My club friend tightened all the connections to the tank. We thought that fixed it. I motored around between sailing stints without filling the tank since he said, after plunking the tank with his wrench, “oh that’s full!” (Note to self: when you know you haven’t filled the tank for five years ... why believe such nonsense) until I ran out of fuel. Guess what happened when filling.... spurtage from the air vent. And leakage from above— on top of the tank. We thought, clog? Yes, there was a clog! It was cleared by a wire through the intake line. Was there a leak after clearing the clog in the line, presumably from tank gunk that settled when aground a year before. Yes, a leak! I figured that there must have been a half cup of fuel above the leak, and it weaped out a failing connection when the clog dispersed. Then we inserted a smaller tube to go through the intake line to pass the tank connection (on top of tank), since that must be the leak location, which is very hard to access. Now we add diesel via mini pump action. Once again, now we have a very active air vent spurting fuel.

a couple observations:
-The leak starts about 30-60 seconds after filling begins
-the tank glistens on top first, then into bilge
-the last attempt, at the moment there was fuel spurting, there was a sucking sound from inside the tank, which then disappeared at approximately the air vent spurt began. (Only reason I can muster is that maybe the tube reached the very bottom, and new fuel was pumping into bottom gunk?)

questions:
Um, what about gravity and geometry??? The air vent connects to the tank right beside the intake, on the top of the tank.is the tank full? Empty? Pressurized? Is the air vent clogged (and how the hell do u clear that)? How could it be, it’s leaking fuel?

Solutions? Long term? Short term? Thank you for reading all the way to the end! I’d really like to sail this summer! New bottom paint and chart plotter/depth sounder and new cushions and curtains are going unused!

 

[Loren Beach]

No experience with your model, but my boat had (past tense) the vents for both the diesel tank and the holding tank up on the back of the transom, but several inches below the top. This is all right for the HT, but the fuel fill point forward on our side deck is higher. (!) So, when adding fuel and getting to the top portion of the tank, that vent would have to have a rag placed/taped under it to catch spurts of diesel. (sigh)

The problem was two fold. First the vent hose had sags in the hose run where they had led it under the side deck, aft, from the settee tank location, and second... ultimately the vent was lower than the fill point.
Always best to have the vent path be, even if only slightly, all uphill from the fuel tank.

Some years ago, I moved the tank vent to the inside of the combing at the end of our bridge deck, and now it's higher, somewhat, than the deck fill fitting. That was when I replaced all hoses, and also fastened up the new vent hose securely so that it has almost no sags to hold any fuel.
No more spills n spurts when refueling. And, when when the boat pitches while motoring into a steep wave, no more fuel emerges from the vent. (Was only a problem with a completely full tank, I should note.)
If your tank is located under the cockpit, at least you have a short hose run, hopefully uphill, to the transom vent.
If... you have fuel leaking out from *any* fitting on your tank , that's another problem. Take the tank out and repair it, or even replace it. I replaced our tank with a larger one in about 2008.
Keep us posted, and best of luck!

 

[Christian Williams]

What Loren said.

You'll have to inspect the connections and location of the air vent line. This may mean disassembly of the tank cover, or making an inspection port, or sawing out the entire tank lid. Yes, access is usually difficult.

 

[Chris Mc.]

I’ve discovered mud daubers like to build their muddy larvae nests in the vent ports. Probing it with a wire may have pushed the larvae casing deeper in the hose. Just a thought to consider.

 

[Rocinante33]

Forsooth! Forsaken by the air vent! Shakespeare would be aghast!

what year and model of Ericson are we talking about here?

I would start taking some components apart. If all the fuel and the vent and the fill hoses are old, then I would pull them off and replace. Take extra care that each hose has a pretty smooth route and no significant bend. Look for any blockage in the old hoses. Try to clean up any previously spilled fuel with absorbent pads.that way it is easier to inspect for leaks. It’s very hard to find access to the fuel tank and hoses. On my boat I had to remove a panel inside a galley locker for access to the fill hose under the deck. Also, access to the tank itself required cabinetry removal....settee bottom, etc. Next check those fittings on top of the tank. They may not be implicated in a clog, but possible sources of leaks. New hoses might fix it, though. At least it’s a start.

 

[windblown]

I have a very similar issue on my 32-3: I get spurts of fuel out the air vent when fueling, no matter how full/empty the tank is. I will be checking the vent hose for sagging. Thank you, Loren and Christian. Of course, it runs in a space I haven't yet been able to contort into.

I also get visible diesel at the fuel sender and the access port over the winter when the boat is on the hard--enough to soak a 2" square of fuel absorbent cloth. The first year, I assumed I had over-filled the tank before haul out.

The next year, we had a failure in the in the fuel/water separator (really, a winterizing failure to drain the water, which apparently froze and cracked the bowl around the drain nut, which was discovered when the nut and a lot of diesel flowed into the bilge at launch). Although we thought we got all the diesel cleaned out of the bilge, we continued to find traces of fuel in the bilge all that summer, particularly after a day on the water of rough seas. Because it tapered off, we assumed there were little puddles of fuel trapped in the TAFG, and it finally cleared.

The next year, we had a little diesel showing up in the bilge again (I have become expert at soaking/skimming/extracting diesel traces so that it ends up in appropriate disposal rather than escaping via bilge pump into the lake). We traced it to the connection at the new fuel pump (professionally installed, by the way).

This winter, we again noticed a little visible fuel at the sender port and access port. (I have never opened the access port, I confess.)

This discussion is very helpful, because I think we may find issues with the vent, supply lines, or tank that may yet need remedy.

 

[Christian Williams]

Common for the sender port to leak after tank is filled. Usually it's not "underwater."

A new gasket solves that, or some sealant goop (Permatex Aviation Form-a-Gasket or similar).

Sometimes the five sheet metal screws of the fuel gauge sender become loose. Moving up to the next size screw fixes that, and they will self-tap into an aluminum tank.

 

[windblown]

Common for the sender port to leak after tank is filled. Usually it's not "underwater."

A new gasket solves that, or some sealant goop (Permatex Aviation Form-a-Gasket or similar).

Sometimes the five sheet metal screws of the fuel gauge sender become loose. Moving up to the next size screw fixes that, and they will self-tap into an aluminum tank.

This so helpful!

 

[Kenneth K]

The problem with the 32-3 is that the fuel sender port (with the 5 sheet metal screws) sits in a cutout about 2" below the top of the tank. If the tank is filled to capacity, the port is not only "underwater," as Christian said, but "pressurized" by the fuel sitting above this level. That little 5-screw plate was never meant to be a pressurized seal and is never going to prevent leaking if the tank is filled above this level. I dealt with this same thing after my first refill.



The trick is to only refill below the level of the sender port. The port seal will hold back sloshing fuel, but not fuel under pressure.

 

[Rocinante33]

One more cause may be that your fuel vent (circled in the first picture) may have actually rusted and with the rust clogging it up. No vent, no fuel fill. Ericson did seem to use some ferrous, non stainless fittings which would rust. With your boat on its side in the mud, who knows? Perhaps just mud clogged, too. I had that rust occur on my holding tank vent and it prevented pump out. If so, try to remove and clean out or replace. Otherwise, use a coat hanger or small screwdriver blade from outside, but if you do that it may send crud down the hose to the fuel tank which would not be good.

One of these would work, methinks;

https://www.fisheriessupply.com/browse?terms=tank%20vents

 

[halliealdrich]

No experience with your model, but my boat had (past tense) the vents for both the diesel tank and the holding tank up on the back of the transom, but several inches below the top. This is all right for the HT, but the fuel fill point forward on our side deck is higher. (!) So, when adding fuel and getting to the top portion of the tank, that vent would have to have a rag placed/taped under it to catch spurts of diesel. (sigh)

The problem was two fold. First the vent hose had sags in the hose run where they had led it under the side deck, aft, from the settee tank location, and second... ultimately the vent was lower than the fill point.
Always best to have the vent path be, even if only slightly, all uphill from the fuel tank.

Some years ago, I moved the tank vent to the inside of the combing at the end of our bridge deck, and now it's higher, somewhat, than the deck fill fitting. That was when I replaced all hoses, and also fastened up the new vent hose securely so that it has almost no sags to hold any fuel.
No more spills n spurts when refueling. And, when when the boat pitches while motoring into a steep wave, no more fuel emerges from the vent. (Was only a problem with a completely full tank, I should note.)
If your tank is located under the cockpit, at least you have a short hose run, hopefully uphill, to the transom vent.
If... you have fuel leaking out from *any* fitting on your tank , that's another problem. Take the tank out and repair it, or even replace it. I replaced our tank with a larger one in about 2008.
Keep us posted, and best of luck!

Ok that’s a lot of info, thank you. To be clear, this is not a bit of spurtage, but a full on fountain. As much as goes in comes out (from my perspective, Jimmy wouldn’t say this yet but he’s only seen it once and I’ve seen it thrice). And no part of either hose is positioned lower than the tank at any point including lower than the fill line, which it is .... not filled to.

on another topic, didn’t I meet you at the Ericson raft up in Anacortes?

 

[halliealdrich]

I’ve discovered mud daubers like to build their muddy larvae nests in the vent ports. Probing it with a wire may have pushed the larvae casing deeper in the hose. Just a thought to consider.

Omg.... something can line in there????? Gonna have to Google that. Thank you, I say, hesitantly...

 

[halliealdrich]

Forsooth! Forsaken by the air vent! Shakespeare would be aghast!

what year and model of Ericson are we talking about here?

I would start taking some components apart. If all the fuel and the vent and the fill hoses are old, then I would pull them off and replace. Take extra care that each hose has a pretty smooth route and no significant bend. Look for any blockage in the old hoses. Try to clean up any previously spilled fuel with absorbent pads.that way it is easier to inspect for leaks. It’s very hard to find access to the fuel tank and hoses. On my boat I had to remove a panel inside a galley locker for access to the fill hose under the deck. Also, access to the tank itself required cabinetry removal....settee bottom, etc. Next check those fittings on top of the tank. They may not be implicated in a clog, but possible sources of leaks. New hoses might fix it, though. At least it’s a start.

1984 26’ her name is Siren. Thank you, that sounds do able.... I used to be athletic so maybe I will be able to fold myself in half to dive through the cockpit hatch and reach the hose connection points across the centerline. Good grief. I swear ladies would be better designers. They don’t like bloody knuckles, so access might be simpler!!!

Game on. At least I’ll start here!

 

[halliealdrich]

I have a very similar issue on my 32-3: I get spurts of fuel out the air vent when fueling, no matter how full/empty the tank is. I will be checking the vent hose for sagging. Thank you, Loren and Christian. Of course, it runs in a space I haven't yet been able to contort into.

I also get visible diesel at the fuel sender and the access port over the winter when the boat is on the hard--enough to soak a 2" square of fuel absorbent cloth. The first year, I assumed I had over-filled the tank before haul out.

The next year, we had a failure in the in the fuel/water separator (really, a winterizing failure to drain the water, which apparently froze and cracked the bowl around the drain nut, which was discovered when the nut and a lot of diesel flowed into the bilge at launch). Although we thought we got all the diesel cleaned out of the bilge, we continued to find traces of fuel in the bilge all that summer, particularly after a day on the water of rough seas. Because it tapered off, we assumed there were little puddles of fuel trapped in the TAFG, and it finally cleared.

The next year, we had a little diesel showing up in the bilge again (I have become expert at soaking/skimming/extracting diesel traces so that it ends up in appropriate disposal rather than escaping via bilge pump into the lake). We traced it to the connection at the new fuel pump (professionally installed, by the way).

This winter, we again noticed a little visible fuel at the sender port and access port. (I have never opened the access port, I confess.)

This discussion is very helpful, because I think we may find issues with the vent, supply lines, or tank that may yet need remedy.

Aha! Leak at fuel pump! We will look there too. We might use that opening to fill the tank, if push shoves. (Don’t worry i have an expert mcGyver) thank you. And yes I’ve become an expert diesel in bilge sniffer. Plus I can now tell just by a slight color difference if diesel is down there.

 

[halliealdrich]

Common for the sender port to leak after tank is filled. Usually it's not "underwater."

A new gasket solves that, or some sealant goop (Permatex Aviation Form-a-Gasket or similar).

Sometimes the five sheet metal screws of the fuel gauge sender become loose. Moving up to the next size screw fixes that, and they will self-tap into an aluminum tank.

Huh, what? The gauge has something to do with this?

 

[halliealdrich]

The problem with the 32-3 is that the fuel sender port (with the 5 sheet metal screws) sits in a cutout about 2" below the top of the tank. If the tank is filled to capacity, the port is not only "underwater," as Christian said, but "pressurized" by the fuel sitting above this level. That little 5-screw plate was never meant to be a pressurized seal and is never going to prevent leaking if the tank is filled above this level. I dealt with this same thing after my first refill.

View attachment 38845

The trick is to only refill below the level of the sender port. The port seal will hold back sloshing fuel, but not fuel under pressure.

My gauge is on the very top. At least that’s one problem I don’t have! Thanks for the tip tho.

 

[Loren Beach]

on another topic, didn’t I meet you at the Ericson raft up in Anacortes?

We drove up. The pot luck under the tent on the dock was a lot of fun. We had hoped to take our boat up to Maple Bay this summer for a re-scheduled rendezvous, but it looks like Canada will not open their borders this year.
Pandemics are inconvenient, to say the least!

 

[halliealdrich]

One more cause may be that your fuel vent (circled in the first picture) may have actually rusted and with the rust clogging it up. No vent, no fuel fill. Ericson did seem to use some ferrous, non stainless fittings which would rust. With your boat on its side in the mud, who knows? Perhaps just mud clogged, too. I had that rust occur on my holding tank vent and it prevented pump out. If so, try to remove and clean out or replace. Otherwise, use a coat hanger or small screwdriver blade from outside, but if you do that it may send crud down the hose to the fuel tank which would not be good.

One of these would work, methinks;

https://www.fisheriessupply.com/browse?terms=tank%20vents

Ayyy, matey, thanks everyone for all this!

 

[halliealdrich]

Update: the top connection of the air vent is loose and the connection to the tank is damp/wet, so I presume it is also loose. I’m going to replace the hose and fittings, but first I have to do some yoga....

“no air vent, no fuel fill” is a motto I will remember! I will also remember to f’ing look at the obvious first, like at replacing or tightening hoses. Duh!

As a kid I remember my dad cursing and futzing around his little race car, a Datsun z-thingy, confounded by the starting problem he could not solve. Finally, he worked through the chain of events that lead to the car starting.... which begins with the fuel tank, and back another step, which begins with fuel. You can imagine the rest (he thought his dork maneuver was hilarious so that was good!). I get to go back one more step, to begin with air! Hopefully there are no more steps to go backward.

 

[nquigley]

The problem with the 32-3 is that the fuel sender port (with the 5 sheet metal screws) sits in a cutout about 2" below the top of the tank. If the tank is filled to capacity, the port is not only "underwater," as Christian said, but "pressurized" by the fuel sitting above this level. That little 5-screw plate was never meant to be a pressurized seal and is never going to prevent leaking if the tank is filled above this level. I dealt with this same thing after my first refill.

View attachment 38845

The trick is to only refill below the level of the sender port. The port seal will hold back sloshing fuel, but not fuel under pressure.

I'd never thought about that before - I must have missed Christian's earlier post about this issue.
This observation raises an interesting possible consequence of filling the boat's tank to the max...
... the fuel sender port is naturally at the deepest point in the tank, at the forward inboard corner, below which is the tank corner in which several of us have discovered pinpoint corrosion holes. I'm guessing that years of overfilling the tank caused an overflow leak from the sender unit's gasket that runs down the outside of the tank to that corner, where it pools around that bottom corner. There was a nasty soup in that corner when I pulled my tank out that seemed like old fuel. By that time, fuel was probably was seeping out of the tank via those pinholes (which were clogged with gunk from inside the tank), and then running in to the main bilges after filling the small pocket around the tank corner. But the original cause of the corrosion was likely a fuel/oxygen soup corroding the tank from the outside-in.
Now I just have to work out the point on my fuel gauge that corresponds to the safe-fill level in the tank.