Water leak at top of water tank - help

[jdy2kgt]

As you can see from the video and pictures I have water pushing out from
1) where the sender goes into the top of the tank
2) where the plastic weld is that makes up the disk the sender is attached to

What can I use to seal these two seams? I've tried making sure not to over fill the water tank but then once we heal over we still get a leak so I need to fix this. Thank you!

 

[jviss]

Welcome to the forum.

I think you mean water tank, not holding tank? Holding tank refers to the toilet waste tanks.

The plastic weld, I can't help you. Almost nothing sticks to that material. Perhaps an auto body plastic welder could fix it?

The sender, mine have fairly thick rubber gaskets.

 

[jdy2kgt]

You are 100% right I meant water tank, post edited. Still doesn't help me stop the leak

 

[Tally Ho]

I don’t know if there is enough material in the welded on disk to break it loose and then use a gasket or some caulk under it and screw /bolt it down to the tank.

For the sender, that should be a pretty easy fix...new gasket or some caulk to seal.

Greg

 

[Rich Stidger]

I agree with what Greg suggested. I would use gaskets. I think you would have problems with sealants due tothe plastic material.

 

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[JamesG161]

We had similar problems with our Polyethylene [Plastic] tank.
Our seam leak was from overfill of the tank.

We ground out a "V" notch around the "flange" leak seam, then filled the notch with 3M 5200.
No leaks, but we never fill the tank to > 95% now.
Jim...

 

[Ralph Johnstone]

If that were my baby, I'd be having regular seizures by now.

Whatever you do, you'll have to do it in place as there's a lot structural and finished woodwork in the V berth to be removed and replaced if you want to pull the tank for repairs.

I don't know what depth you get into with your boat maintenance but if I woke up tomorrow with that problem, I'd be studying plastic welding for repairs to the the poly flange and inserting a soft gasket for the sender flange as mentioned by others here. Mind you, I'm OCD with everything with my boat, so the cost and time involved with plastic welding would be just fine. Maybe even a learning experience.

As far as any sealant sticking to poly, the only one I have found that will hold is Permatex No. 2 which is NOT acceptable for potable water. Also, as this is an internet forum, take this info with a grain of salt and be sure to try it yourself first. Place a dab of Permatex on the poly tank and see if you can dislodge it cleanly after a week or so. Rubbing alcohol will remove it. I've used this on the holding tank and it's held for the last 19 years.

I'll be out to the boat in the next few days, and have a closer look to see if I have an epiphany or holy revelation but it's not looking good from here.

 

[senang]

Drill holes in the disc and tank for bolts. Use cork sealant cut to size. Take bolt that are 1/2 " to long. Grind 2 flat sides on the last 1/2" of the bolt. Remove the disc from the tank. Insert bolts from the INSIDE of the tank (bolts should be a tight fit). Place cork and disc. Place nuts handtight only. Take pliers to hold bolt and tighten nuts in starlike sequence. Should last forever.

 

[jviss]

You know, another answer to this issue is to just do nothing. It only leaks when the tan is very full. When it leaks, it's fresh water, into the bilge. So what?