Puzzled- toon takes on water, but holds pressure

[asdasc]

So here is a puzzle for you. My left U-tube takes on water over the course of the summer. When I pull it out of the water in the fall, I can drain for about 5-10 minutes siphoning thru a half inch hose. You can feel the boat lists that direction as well.

Last night, it was probably 40 degrees or so, I took the cap off and tried again to siphon, and got a little more out, not much. I put the cap back on. This morning in the sun it might have been 45 degrees out, but very sunny. When I pulled the cap, it exhaled, quite a bit actually (maybe 3-5 seconds?).

How can it build pressure if it leaks? I assume the sun warmed it causing it to build pressure. Someone told me it may be foam filled, but I don't think so. I will stick a longer coat hanger wire in there next time to feel around. I was planning to add a little pressure to see where the leaks were before putting it in the water this spring.

 

[5150abf]

Re: Puzzled- toon takes on water, but holds pressure

For it not to hold any pressure it would have to have a pretty big leak, and you are right, the sun heats the tube and causes pressure to build, cold will cause a vacuum too and actually suck water into the tube.

Either you have a leak or a magic tube, my money is on a leak.

To not be filled with foam this would have to be an older boat, the last time I built U tubes was 12 years ago and it was required then.

Get a spray bottle and some dish soap, we use polmolive,(it keeps the guys hands soft) and some air,5-8 psi max and start spraying.

Alot of times when I am looking for a leak I will listen first, alot of times you can hear the air coming out.

Watch the brackets at the front and rear of the tubes, it is a stress point and prone to crack, as the boat runs water gets on top of the tubes and then into the tube itself.

 

[asdasc]

Re: Puzzled- toon takes on water, but holds pressure

thanks 5150. I will Check it out again this weekend.

 

[lowkee]

Re: Puzzled- toon takes on water, but holds pressure

If it holds air, yet lets water in, the hole may be on the bottom of the pontoon and is clogged with a dirt particle when trying to 'exhale' and allows water in while 'inhaling'. The Bill Clinton edition never had this issue, of course

 

[asdasc]

Re: Puzzled- toon takes on water, but holds pressure

Good one! I love Clinton jokes.

Anyway, yes, it is an old one. In fact, I remember it looking very old when I first drove it at my wifes grandfather home almost 25 years ago, so it is AT LEAST that old. My guess is closer to 50 years old, which would make it about the same age as the motor (1959). The idea of dirt clogging the hole on exhale is a good one. I am not sure how I will handle that when the time comes. This weekend I will pump it up ever so gently and see what I can find.

Thanks,

 

[asdasc]

Re: Puzzled- toon takes on water, but holds pressure

Well, I got to work on it some more this weekend. I realized that the bow was sleightly lower, so I jacked it up in front a bit. It is on blocks and now is maybe 8" higher in front. We got a BUNCH of water drained out, but it is still much heavier on the left than the right. The small hose that fits thru the fitting kept getting clogged, and I think there are some old blocks of foam in there, just not filled with it like I imagined. It also seems to be waterlogged and breaking down as it seems like that is the dark orange-ish crud that is coming out with the really clear water. I will leave it another week propped up and hope that more of the water will work its way to the back so that I can drain it further.

Any other ideas? Suggestions?

Thanks,

 

[asdasc]

Re: Puzzled- toon takes on water, but holds pressure

By the way, how much pressure can you blow into a tube with your mouth? We found that by wrapping the siphon tube with a little tape, we could get it to seal up the fitting. Then we could blow into it with our mouths and get the flat sides to 'pop' out just a little. Then it would drain faster and not get so easily clogged with the orange crud.

 

[lowkee]

Re: Puzzled- toon takes on water, but holds pressure

I think at best 5psi. Oddly enough, when testing my pool filter pressure gauge I was curious to know that same fact and I could barely move the needle to 5psi.

If you have an air compressor you can use that, just don't go crazy and pump in 100psi. I'd bet there is a 'max pressure' thread somewhere on here.

EDIT: forgot the word "don't".. a pretty key word in that sentence

 

[5150abf]

Re: Puzzled- toon takes on water, but holds pressure

that is exactly how I do it at work when we get a leaker in, I drill a drain hole and put an air check hose on it and blow the water out.

On a toon that old I would be pretty shy about air pressure and wouldn't go above 5psi.

It would almost have to be a steel tube if it is that old or it could be one of the first aluminum ones, I am pretty sure welding aluminum didn't happen till around that time, late 50s early 60s.

 

[asdasc]

Re: Puzzled- toon takes on water, but holds pressure

Thanks lowkey and 5150. By the way, the thread 5150 posted is the key one about pressurizing pontoons.

If the crud is making a check valve, pressurizing it and looking for leaks may not work. I have been thinking about the way we were blowing bubbles in the tubes. Maybe I can fill them back up with water and form a vaccuum, then listen for the bubbles!

 

[5150abf]

Re: Puzzled- toon takes on water, but holds pressure

You may here bubbles but telling where they are coming from will be next to impossible, with 5psi in the tubes it will blow the crud out of the way and you can see exactly where the leak is.