Fresh Water Large Drain Plug Leak

[Hikingsolo]

On my 34’ 1991 Limited there is an access panel behind the second wheel. Removing the panel reveals a large drain plug in the freshwater tank. When I turned on the auto fill switch water rushed out of the access panel so I removed it to find the large drain plug leaking badly. Tightening the plug did not fully stop the leak. I removed the plug, wrapped it with Teflon tape, and put it back in tightening a few turns by hand and then with a makeshift socket. When I turned on the auto fill there were about six drips per second. Tightening the plug reduced the number drips to once every three seconds, but I can’t get them to stop. I’m afraid of tightening the plug all the way into the tank! The water seems to be coming around the threads as it’s dry on the outside of the plug receptacle. I can’t see a visible crack or feel any kind of crack in the plug receptacle but I do feel a small split in the plug itself. I’m not sure if that’s part of the manufacturing of the plug or not. Any ideas on how I can stop the leak?

[GMFL]

I would remove the plug completely and clean the tank and plug threads with a toothbrush. Check the tank bib for cracks. If no cracks, then use pipe dope (Teflon paste) on the plug threads and re-install the plug. Use a good amount of paste.

[Hikingsolo]

Thanks for the suggestion. Is Teflon paste a material that will need to set up for a while before water is added to the tank? I’ve used gas pipe three sealant but not anything for potable water systems.

[GMFL]

No it does not have to set up and it I’d available at any hardware store in the plumbing section. It works and a sealant and lubricant filling in micro gaps while screwing plug in place. It drys to a putty consistency and I believe it to be superior to Teflon tape on plastic threads. Plastic threads do not have the strength to cut into the tape and that only causes more potential for leaks.

[AtomicNo13]

In my experience, I have found the plug will shrink over time. Ive had a couple do this. The only remedy is to buy a new plug from Airstream. The new style is made of black plastic, not the yellow.

[Silvr_Bullet]

Did you try adding additional layers of Teflon tape?

[GammaDog]

Having just replaced a fresh water tank I'm with GMFL. Atomic could also be on to something... I'd certainly replace the plug based on his experience. Airstream currently uses a non-hardening pipe thread compound on both threaded fittings and slip joints on the fresh water tank. I'm not sure what brand they use, it's light green. My Airstream dealer parts guy didn't know either, but said their service team uses a widely available commercial product. After researching the subject, I used RectorSeal T plus 2. So far, so good. Use it liberally... you want it in every nook and cranny of those threads.

[GMFL]

Originally Posted by Silvr_Bullet

Did you try adding additional layers of Teflon tape?

Again the plastic threads are not really strong enough to cut into the tape.

[harryk]

Get a new 1 1/2 inch plug from lowes or home depot. I found some with more thread area which means that the plug was actually about a 1/2" longer and it had a wrench end instead of the hole. Then teflon tape....clockwise. Near the wrench end I put 10 wraps and tapered towards the other end. The 10 wraps is key.
While you are there, consider putting a fresh water hose thru the hole and move it around to clean. You are gonna get wet but your tank will be clean !

[Silvr_Bullet]

If you need To go the route of a new plug I would bring the old with you, the same thread pattern is important in addition to the 10 wraps of Teflon tape, when I wrap it I will do near the most it will hold on the threads, tapes cheap do it a couple of times with tape till it feels snug not loose when you hand tighten it.

[Hikingsolo]

6 layers. I’ll try the paste. A local guy suggested both. Tape then paste.

[Hikingsolo]

Thanks for the specific name!

[Hikingsolo]

Originally Posted by harryk

Get a new 1 1/2 inch plug from lowes or home depot. I found some with more thread area which means that the plug was actually about a 1/2" longer and it had a wrench end instead of the hole. Then teflon tape....clockwise. Near the wrench end I put 10 wraps and tapered towards the other end. The 10 wraps is key.
While you are there, consider putting a fresh water hose thru the hole and move it around to clean. You are gonna get wet but your tank will be clean !

I wondered if the plug was metric since the hex head was metric. I thought about going to
Lowe’s/Home Desperate but the local stores are somewhat sketchy. My local RV place was no help. A call to Airstream may be next if the tape and paste don’t work.

[AtomicNo13]

Harryk,
The thread pitch is different on the plugs fromthe hardware store, I suspect you might damage the tank side threads, or worse crack the bung.

[harryk]

Both the tank, the old plug, and the new plug are NST....national standard pipe thread.

[madpiper]

I can't find a replacement plug for my 1988 Excella 1000 fresh water tank drain plug. Mine is 1/75" in diameter and it looks like it has 2 hairline cracks in it.