Fresh water tank fill bung broke out.

[Roadking Larry]

Saturday I filled the freshwater tank on my '76 Cal. I filled it right to the top. Of course when I put the cap back on the fill bung I discovered that the threaded bung molded into the tank was breaking around the threads. It's nearly 40 years old and looks to be at least partly caused from over tightening the plug. The tank and fill access is under the v-berth, it takes running a hose to the fill neck to use. Removing the tank for a replacement would be a major undertaking requiring a nearly complete tear out of the V-berth area. Is there any kind of replacement type fill caps that can be installed from outside the tank? I have limited clearance from the tank top to the v-berth floor, probably not more than 1.5" or so. Current access to the tank top filler neck area is pretty limited but could be enlarged some if needed. I've been searching the web but not entirely sure what I need or if what I want exists.

Sailing with 20-25 deg of heel later that day did give my forward bilge areas a bit of a freshwater rinse though.

 

[Peggie Hall HeadMistress]

There's no deck fill fitting for the water tank?

 

[Benny17441]

Look in automotive parts and accessories for fuel cell bungs. You should find one that may be suitable for a replacement.

 

[Ron20324]

replace it with an inspection port?

 

[wufibugs]

Is there enough left of the bung to put a hose on? If so, you could create a deck fill set up.

 

[Roadking Larry]

Here's a pic to show what I've got to work with. The "decking" is the bottom of the v-berth. I could enlarge the access hole and add a cover plate to keep from having a divot under the cushion.




I'll take a look at fuel cell bungs and see if that might offer a fix.

 

[Benny17441]

Now that I see it you might try to epoxy it back on as a temporary measure. Apply a generous amount of epoxy and make sure you clean the threads before it starts drying. As long as you do not overfill the tank I think it might be all right. Fuel cell bungs can be attached from the top by rivets; it should bring a gasket and a threaded cap.

 

[Roadking Larry]

I've considered some kind of glue/adhesive. Since this isn't a pressurized tank nor do I need to worry about venting noxious fumes I might be able to get by with that. I wonder if this is one of those rare applications where 3M 5200 might be the right choice.

 

[Peggie Hall HeadMistress]

If the tank is polyethylene, nothing will bond permanently to it. If it's not, you can glue the bung back in with anything you like.

 

[Roadking Larry]

Not sure what it's made of as far as I and the PO know it is original equipment circa 1976.

 

[Peggie Hall HeadMistress]

Surely you've seen it and know whether it's metal--steel or aluminum....fiberglass...or translucent plastic, which would be PE.

 

[Roadking Larry]

Plastic it is just not sure which type/grade. I was rushing and didn't make a complete post. being 40 years old I had a brief thought maybe polystyrene but that would be too brittle for the application.

I have a friend with a plastic welding set up used to repair rotomolded plastic boats might give that a try first.

Thanks to everyone for the input, if I come up with a good fix short of replacing the tank I'll update here.

 

[Benny17441]

Peggie is correct, I thought the bung itself was just cracked but I can see where it might have also separated from the tank. I would just try one of those epoxy recommended for plastics. It should work for some adequate period of time before it separates again. The only forces applied to the bung are when the cap is screwed on and off. I recently had a similar problem with a separated handle from a hatch and gluing worked for the two weeks it took to find and install a replacement lens.