Replacing black and grey water drain lines

I completed the job yesterday and learned a few things. For sealing the ABS pipe to the holding tanks I used pipe thread sealant. It is like toothpaste for consistency and helps the pipes slide together as well. I put plumbers putty on the ABS taper before pushing it in so it could seal at the taper in the back of the hole.

I used two hose clamps with tighteners on opposing sides. I put a rubber elbow on the 1 1/2" grey line in case I ever need to have a clean out and makes it easy to replace valves or pipes this way.

My grey lines had two supports on it and we replaced the bars coming down to them as I pushed the valves and connection about 3-4" farther out. I had to crawl under the trailer to drain the black water before and we all know what is on the ground in those areas!

Finished it yesterday about 2 pm and added about 50% water to each tank. Checked it this morning and there were no leaks! Leaving Saturday with my 9 year old on a 7,800 mile road trip so it will be nice to have things working perfectly.

One last tip, I checked the water pump area and all the lines this morning to make sure there were no leaks before taking off. Never know what crept up over the winter to haunt one! I hope someone can use this for their project. Thanks for the tips!

I had never seen rubber no hub elbows before. I looked them up and that may help solve some problems. I bet it also helps with vibration damage to the pipe seals. Thanks.

lamopar wrote:
I wish I could just cut the 3" pipe and repair from there but the ABS comes out of the tank at a 45 with another 45 going right into the drain valve which is where the break is located. I have not had any luck locating the exact style of drain valve with the T in the same location so it won't attach back to the 1 1/2" line with out modifications there also and if I do it makes it even farther under the trailer. I am thinking I would like to have it stick out a bit farther as it is a real challenge to get to the black water valve now.

I looked and it seems the goop is the soft sealant that was used at the tank so it should come out pretty easy I hope. I figure the unit is 7 years old so it is probably a good idea to change out both valves now before they fail. Would you agree?

You can also get rubber no-hub ells.

I have a leaking double rotating waste valve, all 3" glued ABS including the tank with minimum ABS pipe distances and no hoses.

I'm concerned about getting enough clearance to replace the seals. Suggestions appreciated.

09 42' Scepter.

I wish I could just cut the 3" pipe and repair from there but the ABS comes out of the tank at a 45 with another 45 going right into the drain valve which is where the break is located. I have not had any luck locating the exact style of drain valve with the T in the same location so it won't attach back to the 1 1/2" line with out modifications there also and if I do it makes it even farther under the trailer. I am thinking I would like to have it stick out a bit farther as it is a real challenge to get to the black water valve now.

I looked and it seems the goop is the soft sealant that was used at the tank so it should come out pretty easy I hope. I figure the unit is 7 years old so it is probably a good idea to change out both valves now before they fail. Would you agree?

beemerphile1 wrote:
Just cut the piping where needed and use a no-hub rubber coupler. No need to start at the tank unless that is where it broke.

I agree, no reason to fix things that don't need fixing and if your gluing ABS pipe use ABS glue and don't try to reinvent the wheel.

Just cut the piping where needed and use a no-hub rubber coupler. No need to start at the tank unless that is where it broke.

If it has the hose clamp holding the pipe to the exit fitting of the tank, you remove the hose clamp and use a LARGE Channel lock pliers and put pressure on the pipe by attempting to rotate the exit pipe back and forth. The adhesive will break loose. It is NOT a hard glue, but a soft glue. Never had one break the tank. Now, if it was an ABS tank with a glued ABS exit pipe, you cannot remove it. ABS glued tanks do not have hose clamps. Doug

So if the ABS is glued in place getting it out without damaging the tank would be a challenge I am guessing? I was planning on replacing the system as when it was in for repairs a few years ago we had freezing weather and the Y connection for the 3" and 1 1/2" pipe with the 3" valve cracked where the 1 1/2" enters the 3". I also see a slight bit of leakage at one of the 1 1/2" connections. We are leaving on a 7 week trip across the country and I don't want any leaks. I thought of trying to do a better job a repairing the pipe as I used RTV on it with some tape and had limited success. I was guessing it was better to just replace everything but if the pipes are glued to the tank that may be a severe challenge.

If you have the hose clamp at the exit fitting of the tank, the ABS insert is glued and held in place by that hose clamp. I use Sikaflex as the sealant to glue and seal the ABS fitting to the exit of the tank. The hose clamp just holds the 2 parts snug. The Sikaflex does the job. If you are talking about a rubber splice that has a hose clamp on each end, then yes, you loosen the 2 clamps and the ABS pipe pulls out. There should be no adhesive on this type fitting. Doug