Montana Black Tank Valve Gates

[adeakins]

I’ve had this 2018 3791RD for about 4 years now. The valve for the black tank has always been more difficult than the grey tank valves. Now, that valve is near impossible to fully open or close. I’m thinking the rod or cable - I’ve heard different versions as how that mechanism works - is rusted. I was going to have it addressed by my favorite RV mobile tech along with a myriad of other repairs when Helene roared through town (Brevard, NC). Now, I’m halfway to my next resident volunteer gig in northeast Alabama (Decatur / Huntsville). When I get there, the black tank issue will be first priority. As our 5’ver is a 4-season unit, I have to contend with the bottom cover … it has to removed or cut open. If removed, that does not look like a 1 person job. If cut open (and “bottom-taped” back), how do I know where to cut? I would be very appreciative if anyone with DIY experience can share. Or, if not that, then the name of a good mobile tech near Decatur, AL.

 

[NH_Bulldog]

Does your unit have a wet bay where the cable valve pulls are located? I have a new Cougar and the cable pull for the black tank was a bit stiff, so I removed the back wall of the passthrough and rerouted the cable to eliminate sharp turns, then sprayed in some cable lube.

Depending on where your tanks are located, you might be able to see the valves from the basement area. If absolutely necessary to cut into the belly, you could poke a nail down through from above to pinpoint the location. Aside from the coroplast belly, you will also have Astrofoil bubble insulation to contend with. If you have to cut, do a 3-sided opening with the end closest to the front acting as a hinge so that when you put it all back together and tape it, the wind won’t catch the edge and tear it open.

 

[chuckster57]

In most fifth wheels the waste tanks are located where you can see the tanks and the cables if you remove the back wall as suggested.

I have dropped many underballys by myself. Just take out enough to service the valve, then using a creeper work your way back up one screw at a time on each side.

 

[adeakins]

Does your unit have a wet bay where the cable valve pulls are located? I have a new Cougar and the cable pull for the black tank was a bit stiff, so I removed the back wall of the passthrough and rerouted the cable to eliminate sharp turns, then sprayed in some cable lube.

Depending on where your tanks are located, you might be able to see the valves from the basement area. If absolutely necessary to cut into the belly, you could poke a nail down through from above to pinpoint the location. Aside from the coroplast belly, you will also have astrofoil bubble insulation to contend with. If you have to cut, do a 3-sided opening with the end closest to the front acting as a hinge so that when you put it all back together and tape it, the wind won’t catch the edge and tear it open.

Good advice. I do have a wet compartment. I will check it out tomorrow. Thanks.

 

[workinonit]

I wouldn't suggest cutting the coroplast I don't think you could get it taped back together and have it hold. I took mine down partially for the exact same reason you are having so I could lube the cable.

 

[NH_Bulldog]

I wouldn't suggest cutting the coroplast I don't think you could get it taped back together and have it hold. I took mine down partially for the exact same reason you are having so I could lube the cable.

In my last camper, I had to open the belly in a couple of areas to do a plumbing and floor repair from underneath. It was pretty simple to re-secure the coroplast where I had cut it open. Using an awl, I poked holes every few inches around the perimeter of the cut area and then using zip-ties, "stitched" the flap closed, clipped the "tails" and then ran a bead of black sealant along the cut. I never had any issues of it coming open or keeping it weathertight for the years or tens of thousands of miles we traveled with the camper after that.

 

[chuckster57]

Scrim tape works real good also. I’ve seen that stuff stay on for years.

 

[Notanlines]

What Bulldog and Chuckster said^^^^. Gorilla tape or scrim tape, no problem. Also it will be worth your time to try to lube the cable itself. With the cable open use a spray can with a little red hose and try to force it in the cable with your fingers tight around the opening. Send lots of it in the cable.

 

[workinonit]

Mine was pretty simple to get down without cutting. Those gun type fasteners are a trick to get out but I replaced them with self tappers.

 

[Pathfinder75]

In most fifth wheels the waste tanks are located where you can see the tanks and the cables if you remove the back wall as suggested.

I have dropped many underballys by myself. Just take out enough to service the valve, then using a creeper work your way back up one screw at a time on each side.

Agree with Chuckster57.
Your Montana has a drop frame so your valves are forward of the 3" Black drain tube. Of course your galley tank valve will be back farther near axles. See photo showing pipes leaving black and gray tank pipes join then exiting drivers side. Photo view from door side.
Drop under belly from rear of drop frame as needed to access (should not need to cut material). The hex headed fasteners are not threaded (more like a nail) but with drill or impact will come out when spinning and a THIN pry tool assisting to pull them out.

 

[440scout]

This is what I used to lubricate all the dump valve cables. The email below is to order one the devices. It requires an aircompressor and includes oil which is forced through the cable to the valve. He has a video available on YouTube.

NOTE: Private email addresses are not allowed on the forum. Posting the link to a YouTube video is permitted, but not personal or commercial emails for product advertising.

 

[Mark-wny]

It might be a little late for this, but once you get them freed up, keep the cables lubed. I keep the can right there so that I don’t forget, every time I dump the tanks, I spray them.