Black Tank Leak Repair
After a week or so on the road during a recent trip out west, we found that we had a tank leak. We were in Bryce Canyon, stopped at a lookout, and found water trickling out of several places at the rear of our 2010 Outfitter Apex 9.5. I realized from the odor it was either the gray or black tank. I had previously made a repair to the shower inlet line to the gray tank (see previous post), so my first thought (hope?) was the problem was there. We found the dump station at Bryce and I rinsed the black tank out thoroughly.
The black tank is in the back corner passenger side, with limited access. There are three openings into the tank: the inlet from the toilet; the drain line; and a top vent. The valves are under a “kickplate” as you step into the camper, and I could remove the kickplate and confirm there was not a leak at the 3” drain outlet from the tank. I also removed the camper from the truck, as there is a side access panel to the basement, right in front of the black tank, that can only be opened when the camper is off the truck. You can’t see much of the black tank except the side of the tank, and there is no clearance above, as the tank basically takes up the whole space between the basement floor and the camper floor. I could see the shower drain line to the gray tank, but with water everywhere I still couldn’t tell if the gray or the black tank was the problem. There was no obvious problem at the gray tank connection.
After a few days of experimenting not using the black tank, and then filling it with fresh water, I confirmed that the black tank was the culprit. The tank didn’t leak under static conditions. When I filled it approximately half-way, no leak was evident….until I drove around on a bumpy road, and found water really coming out…not just a weepy type of leak. So we didn’t use the black tank for the remainder of the trip, which was a bummer, because we were out for another 4 weeks.
When I got home, I dumped fresh water into the toilet inlet using an orange Home Depot 5 gallon bucket. At ~11.5 gals, water started pouring out. The tank is nominally a 16 gal tank, so I was afraid that I had a cracked tank. I call Bob Ward at Outfitter, who said they had never seen a broken tank and did not see any way for the tank itself to be a problem, and that it had to be one of the openings. He suggested removing the taillight. I did that, and found that the vent is a 1.5” ID rigid PVC line, and that it was not attached to the tank….I could squeeze my fingers into the narrow opening between the shower surround and the camper wall, and move the pipe back and forth. There was not enough clearance to remove the pipe, but at least I confirmed where the problem was (at least, I hoped it was the only problem :) ).
I removed the toilet and used a dental mirror, dropping a small light into the black tank, and even a camera scope to diagnose the problem. Very difficult. I could only see three options to repair: drop the basement floor, which is a major, complex job; remove the shower surround, which would involve removing the roof; or cutting a hole somewhere. I determined that I could fit a 4” marine deck plate on a beveled surface on the shower surround behind the toilet. I purchased this adjustable hole saw from Harbor Freight (part # 69063) for $5.99, which did a great job cutting the necessary 4.5” hole, but was only good for this job because it was worn down so much cutting through the fiberglass:
I wore a dust mask and cut in three sessions of ~20 seconds each to allow the dust to clear and the tool to cool down:
Now I could see where the rigid PVC pipe should have fit through a rubber grommet into the tank. The vent pipe made two 45-degree turns into the tank, and I was able to use a hacksaw to cut out about a 10-inch section just above the 45s. The vent pipe runs straight up from there, and then turns 90 degrees to an exhaust flange, which is mounted high on the rear wall of this camper (which is a pop-up, so can’t go through roof). An examination of the rigid pipe shown that it had not pulled out of the grommet, but rather had broken at the tank fitting:
I tried to remove the rubber grommet and the short piece of rigid PVC pipe inside it, but it didn’t move even after great effort, and I was afraid I would do real damage to the tank. I was afraid of cutting it out, the way I did on the gray tank repair, due to the extremely limited access if something went wrong. I then thought about using a 2-part epoxy and simply gluing the pipe back in place, but with a polyethylene tank and nylon insert (both notoriously difficult to adhere to), a rubber grommet, and the desire to never have to do this again, I decided on a different approach.
I purchased a mushroom fitting (threaded to make a compression seal against the tank wall on one end, and with a barbed connection on the other end) from West Marine, along with some 5200 marine sealant from 3M:
I threaded a flexible wire down through the vent hole, and was able to pull it out of the inlet. I threaded the wire through the mushroom fitting, configuring the wire so that I could pull it out the top after I got the fitting in place on the tank. I applied the sealant, and carefully pulled the fitting into place, applied more sealant, and then dropped the nut down the wire and tightened the fitting against the tank wall. Sounds easy, right?…..(hint: on jobs like this, I have learned to tie a small flexible wire to tools, lights, etc, in case you drop them in a space where you can’t retrieve them.)
I then threaded a length of ¾” flexible vinyl tubing down from the exhaust flange, inside the rigid PVC pipe that I abandoned in place, and used a hose clamp to connect to the barbed fitting. I personally think all connections to tanks on a camper ought to be flexible, because the camper….wait for it…flexes. The purpose of the vent line is to simply let decomposition gases out, and allow air in to prevent a vacuum when dumping the tank, so the size can be small. (Note: ¾” turned out to be the minimum barb size because I needed a minimum mushroom head size to prevent pulling through the 1.5” opening in the tank.)
The sealant has a cure time of a week, so I had to wait to leak test before I buckled everything up. I was glad to see that the flexing that had broken the exhaust line hadn’t caused any other damage.
Incidentally, we don’t do heavy off-roading with our camper. We do go on washboard roads such as Hole-in-the-Rock, and hit occasional potholes, but that should be normal wear-and-tear in the truck camper world.
All in all, this was a long and tedious project, between diagnosing the problem, figuring out a plan, getting the parts, and then making the actual repair. I probably spent 40 hours total. Out-of-pocket costs were cutting tool ($6); deck plate ($20); mushroom fitting ($20); 3M 5200 Sealant ($15); and vinyl tubing ($8), which totals
The black tank is in the back corner passenger side, with limited access. There are three openings into the tank: the inlet from the toilet; the drain line; and a top vent. The valves are under a “kickplate” as you step into the camper, and I could remove the kickplate and confirm there was not a leak at the 3” drain outlet from the tank. I also removed the camper from the truck, as there is a side access panel to the basement, right in front of the black tank, that can only be opened when the camper is off the truck. You can’t see much of the black tank except the side of the tank, and there is no clearance above, as the tank basically takes up the whole space between the basement floor and the camper floor. I could see the shower drain line to the gray tank, but with water everywhere I still couldn’t tell if the gray or the black tank was the problem. There was no obvious problem at the gray tank connection.
After a few days of experimenting not using the black tank, and then filling it with fresh water, I confirmed that the black tank was the culprit. The tank didn’t leak under static conditions. When I filled it approximately half-way, no leak was evident….until I drove around on a bumpy road, and found water really coming out…not just a weepy type of leak. So we didn’t use the black tank for the remainder of the trip, which was a bummer, because we were out for another 4 weeks.
When I got home, I dumped fresh water into the toilet inlet using an orange Home Depot 5 gallon bucket. At ~11.5 gals, water started pouring out. The tank is nominally a 16 gal tank, so I was afraid that I had a cracked tank. I call Bob Ward at Outfitter, who said they had never seen a broken tank and did not see any way for the tank itself to be a problem, and that it had to be one of the openings. He suggested removing the taillight. I did that, and found that the vent is a 1.5” ID rigid PVC line, and that it was not attached to the tank….I could squeeze my fingers into the narrow opening between the shower surround and the camper wall, and move the pipe back and forth. There was not enough clearance to remove the pipe, but at least I confirmed where the problem was (at least, I hoped it was the only problem :) ).
I removed the toilet and used a dental mirror, dropping a small light into the black tank, and even a camera scope to diagnose the problem. Very difficult. I could only see three options to repair: drop the basement floor, which is a major, complex job; remove the shower surround, which would involve removing the roof; or cutting a hole somewhere. I determined that I could fit a 4” marine deck plate on a beveled surface on the shower surround behind the toilet. I purchased this adjustable hole saw from Harbor Freight (part # 69063) for $5.99, which did a great job cutting the necessary 4.5” hole, but was only good for this job because it was worn down so much cutting through the fiberglass:
I wore a dust mask and cut in three sessions of ~20 seconds each to allow the dust to clear and the tool to cool down:
Now I could see where the rigid PVC pipe should have fit through a rubber grommet into the tank. The vent pipe made two 45-degree turns into the tank, and I was able to use a hacksaw to cut out about a 10-inch section just above the 45s. The vent pipe runs straight up from there, and then turns 90 degrees to an exhaust flange, which is mounted high on the rear wall of this camper (which is a pop-up, so can’t go through roof). An examination of the rigid pipe shown that it had not pulled out of the grommet, but rather had broken at the tank fitting:
I tried to remove the rubber grommet and the short piece of rigid PVC pipe inside it, but it didn’t move even after great effort, and I was afraid I would do real damage to the tank. I was afraid of cutting it out, the way I did on the gray tank repair, due to the extremely limited access if something went wrong. I then thought about using a 2-part epoxy and simply gluing the pipe back in place, but with a polyethylene tank and nylon insert (both notoriously difficult to adhere to), a rubber grommet, and the desire to never have to do this again, I decided on a different approach.
I purchased a mushroom fitting (threaded to make a compression seal against the tank wall on one end, and with a barbed connection on the other end) from West Marine, along with some 5200 marine sealant from 3M:
I threaded a flexible wire down through the vent hole, and was able to pull it out of the inlet. I threaded the wire through the mushroom fitting, configuring the wire so that I could pull it out the top after I got the fitting in place on the tank. I applied the sealant, and carefully pulled the fitting into place, applied more sealant, and then dropped the nut down the wire and tightened the fitting against the tank wall. Sounds easy, right?…..(hint: on jobs like this, I have learned to tie a small flexible wire to tools, lights, etc, in case you drop them in a space where you can’t retrieve them.)
I then threaded a length of ¾” flexible vinyl tubing down from the exhaust flange, inside the rigid PVC pipe that I abandoned in place, and used a hose clamp to connect to the barbed fitting. I personally think all connections to tanks on a camper ought to be flexible, because the camper….wait for it…flexes. The purpose of the vent line is to simply let decomposition gases out, and allow air in to prevent a vacuum when dumping the tank, so the size can be small. (Note: ¾” turned out to be the minimum barb size because I needed a minimum mushroom head size to prevent pulling through the 1.5” opening in the tank.)
The sealant has a cure time of a week, so I had to wait to leak test before I buckled everything up. I was glad to see that the flexing that had broken the exhaust line hadn’t caused any other damage.
Incidentally, we don’t do heavy off-roading with our camper. We do go on washboard roads such as Hole-in-the-Rock, and hit occasional potholes, but that should be normal wear-and-tear in the truck camper world.
All in all, this was a long and tedious project, between diagnosing the problem, figuring out a plan, getting the parts, and then making the actual repair. I probably spent 40 hours total. Out-of-pocket costs were cutting tool ($6); deck plate ($20); mushroom fitting ($20); 3M 5200 Sealant ($15); and vinyl tubing ($8), which totals
