Replacing my belly pan and drilled through my black water tank

[Bwilson11]

What's the best way to repair a small drill hole in the bottom of my black water holding tank??

[J. Morgan]

I would consider putting a glob of epoxy on a screw and simply screwing it in.

[Belegedhel]

Your tank is likely made of roto-molded poly-ethylene. It is pretty hard to find glues/epoxies/caulks that will stick to it. If you can find something, then definitely try gooping it up. There was a recent thread where a guy had a leaking fresh water tank in a 2000's vintage trailer. It looked like a spun on fitting had separated from the tank. He said that he repaired it with with some kind of marine epoxy. Maybe worth a try if you can find the thread.

Otherwise, you might be able to repair it with plastic welding, or a spun-on blank fitting (plug).

[J. Morgan]

Another take on this might be to use a tap, tap threads into the tank, coat a proper sized screw or bolt with epoxy and screw it in.

It it leaks you are out a few bucks and a few minutes, if it works, you are out of the woods for a few bucks and a few minutes.

Is the repair fails, the attempted fix won't screw up anything.

I have a feeling that this fix will work and work well.

[Jim Foster]

You might try using JB Weld epoxy. It comes on two small tubes.
Another great epoxy is Marine Tex. Marine Tex tends to flow a little before it goes off. You might try mixing a small amount, forming it into a dowel shape, inserting half of it onto the hole, spreading the outside part, then use a hit dryer to slightly hear the area. It may spread the material inside before it starts to harden.

Or, you could use either of these products to heavily coat a screw to plug the hole. That might be the surest method. I would use some 80 grit sand paper to roughen up the area around tho hole to give the epoxy a "tooth" to secure to. Forgive me for using a preposition to end a sentence with.

Good luck.

[TG Twinkie]

Look for a product called LEXELL in your local lumber store.
Tapping the hole is a good idea. Use a Stainless Steel screw. Apply the LEXELL to the treads. Screw it in.
I swear this stuff will stick to water.

[Bwilson11]

I'll let ya know if the screw and epoxy / sealent works!

[Wolfe]

Done that way more than i care to rember, you need a O-ringed seal screw.
Call APM HEXSEAL at 201-569 5700 Tell them about it, ask for a free sample.
I think a (OVERSIZE PAN HEAD STAINLESS 10-32 UNF should do it )
WW GRANGER sells them 100 pc box just in case, best of luck-Jim

[perryg114]

I like the O-ring sealed screw approach. You can put some RTV over the screw head for added protection.

Perry

[RickDavis]

An O ring or flat rubber washer on a sheet metal screw. I am assuming a small hole but you could probably do this up to a 1/4 inch or more

[perryg114]

By the way, you can get short double ended sheet metal drill bits at mcmaster.com. You can chuck them up in the drill so that only about 1/2" protrudes. This makes it a lot less likely that you will drill through the tank. Usually there is about 1" of foam under the tank.

Perry

[AtomicNo13]

Drill the hole bigger, get a rubber well nut, tighten with a stainless bolt. I suspect epoxy will not stick! If you must try glue, I suggest gorilla glue. It will expand on both sides effectively making a seamless 2 sided cork. You don't want this to fail with the pan in place with your wife and kids away from home. Deal breaker!

[Cannonball]

3M 5200, made for marine use. It is rated for use below the waterline on boats. Should stick to anything.

[J. Morgan]

"Everything should be as simple as possible but not simpler."

-Albert Einstein

[J. Morgan]

If a decent epoxy is applied to clean, dry, freshly cut threads it will stick and damn good,

A person could add some insurance by scuffing the area where the screw or bolt head will contact the bottom of the tank just to be sure if there are any doubts. (I would scuff it aggressively)

Epoxy WILL form a mechanical bond to abs to the effect of sealing the threads of a screw against a gravity leak no problem.

[airdreamers]

I used J B Weld epoxy. Excellent results. Make sure you drain the tank and let it dry. Apply and let sit for 15 hours as the instruction say. Worked like a charm. Nothing like a water leak to frustrate the you know what out of someone, good luck.

[silverbp]

I build green underwater fishing lights. Have for years. I use a two part M. grade epoxy and I've never had an issues. The stuff is bullet proof and once applied wont come off or leak. Just sand area to give epoxy something to grab onto clean and let it stand overnight. Im sure it will work. Let me know if you have any question as to where I got the stuff.


Sent from my iPhone using Airstream Forums silver bp

[dbj216]

Hi All, I worked in a rotomold plastic shop for four years. Polyethylene is a thermoplastic. The cross linked versions and nylons are not. So we repaired many, many leaky tanks by "welding" polyethylene to polyethylene at about 300 degrees. We had "wire feed" heat guns that would feed the poly into the heated area, similar to a hot melt glue gun. Otherwise finding a stick of polyethylene and using a hot heat gun, or soldering iron, you can melt the hole and feed in new poly. Let it form a glob and then sand it smooth when it cools.

Polyethylene tanks are very repairable. Like others have said, we did not find any adhesives that would hold on it. But we puddled polyethylene into some pretty big holes and then sanded with Scotchbrite disc so you couldn't tell it was repaired.

Practice on some scrap pieces first. It isn't hard. Even I can do it!

David