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Poppy_s_5th_Whe's avatar
Aug 29, 2014

My Epic Repair Project

Well, just finished my big repair project. I previously posted about my broken black water tank in my 3 year old 5th wheel.

I first noticed this problem on July 29th and I finished today so 1 month! The job ended up being much more time consuming than I thought it would be.

It was easy to remove the coroplast. I did cut it into about 5 sections. 3 of the cuts I was able to make where there are cross members, which made reattachment much easier, and 2 were not.

Removing the tank was frustrating because there are 4 different connections to deal with. The toilet inlet, air vent, flush valve and the outlet. I had to partially remove the grey tank just to have room to remove the black tank. It also required emptying out the pass through storage and removing a wall to access the drain and vent pipes from above.

Once it was finally out and inspected and pondered I decided to order a new one versus trying to repair this. I found the exact OM tank though Amazon and got it almost half what the manufacturer's direct distributor wanted with the added bonus that they were charging $120 for shipping and, as an Amazon Prime member I paid $0 shipping.

The longest delay in this project was acquiring all the fittings and parts I would need for reassembly. No one local had a couple of the pieces so back to special ordering.

Replacing the tank was even harder than removing it because it's discharge and the gray water discharged are joined with a "Y" fitting. There's only so much room in there and very difficult to maneuver the pipes and fittings.

While I waited for parts I took the opportunity to do some clean up in the belly like rerunning heater hoses and remove excess length and kinks! I also changed out the 1/8" silver bubble insulation with 1" R-Tech rigid foam board insulation.

I also added a BAL Hide-A-Spare, a new storage tube for my sewer hose and ran power from my inverter in the forward compartment, to the rear wall of the trailer in the kitchen. So, I kept busy.

I reassembled a section at a time. The sections that were not at a cross member required fabricating something to attach the 2 edges of coroplast to so I used 2 pieces of aluminum angle stock (an idea I stole from someone else who did some under belly work so a shout out to him). On the joints where there was a cross member I still used 2" wide flat aluminum stock to cover the edges and screwed it into the cross member with self taping screws. I also used a full roll of Gorilla Tape (absolutely love this stuff, way better than basic duct tape). Then I reapplied expanding foam insulation everywhere something sticks through the coroplast.

One thing I really want to pass on is I got so much miss-information from a couple of local RV repair facilities, especially my local Camping World. I couldn't believe how many wrong parts they tried to sell me telling me "that's the way we would do it"! Man am I glad I didn't take it to them to fix!

Anyway, 4 weeks with the last 2 being 6 - 8 hours a day and it's all done! I am beyond thrilled.

I took almost 100 pictures and many won't make too much sense but they are in chronological order from the very beginning to the end.

Here's the link and if you choose to look and have any questions about what you're looking at or what I did, feel free to ask.

Let's see if this link works:

http://smg.photobucket.com/user/blown96ws6/slideshow/Trailer%20underbelly%20holding%20tank%20repair
  • rjxj wrote:
    Good job. Good job on the pics too. Do you had to run with full tanks at times?


    I doubt I have ever run with full tanks. If we are on a road trip where we might be at each spot maybe 1 or 2 days, I will go a few stops before emptying but never past 3/4. If you are trying to figure out how that crack developed in the first place, my money is on manufacturer defect. I found nothing that could have caused it. I did re-drill to relocate the support that runs along that side of the tank so it is closer to the body of the tank. The tank flanges are just the ABS with no special support or thickness.

    shadows4 wrote:
    Awesome work Paul!! Looks better than new. How did you like the Horst probes? None of my tank monitors works and haven't since I have owned the trailer. Also what did you think of the Bal-Hide a spare? Been thinking of doing both of these mods. Good luck, John


    I was impressed with how different the Horst probes are over the OEM probes. I don't know if you've ever seen the OEM style but the contact point in the tank is just basically a button. I haven't used the holding tank, other than to fill and empty with fresh water 3 or 4 times checking for leaks so I don't really know how they will perform under normal use.

    I really like the Hide-A-Spare. It does exactly as advertised. It was fairly easy to install only hampered by the aluminum skirt around my trailer (and most other newer units) that hides the main frame (in my case I beam). As with anything, measure twice, drill once. I found it difficult to find good reference points to make sure I located the 2 mounting brackets properly. Since mine is in front of the axles, I used the front landing gear as reference points. I secured the brackets with 2 self tapers and 2 bolts with lock nuts.
  • Outstanding work Poppy. Thanks for the write up and pics. For those with a Cougar, you might want to book mark this.
  • Awesome work Paul!! Looks better than new. How did you like the Horst probes? None of my tank monitors works and haven't since I have owned the trailer. Also what did you think of the Bal-Hide a spare? Been thinking of doing both of these mods. Good luck, John
  • Good job. Good job on the pics too. Have you had to run with full tanks at times?
  • Great work but I only got a "Sorry this page doesn't exist" when I tried to open your link.
    I'd really like to see them though.
  • Hi Paul,

    I applaud the decision to go for a new tank. The labor is far more the determining factor and I'm sure a new tank was the right choice.