Well, I put it off as long as I could, but I need to hit the road for the season soon and I needed to replace my green wastewater hose. What I have found is that this is a fairly rugged hose, as long as you don't pull on it too hard. It has a spiral wire reinforcement that's practically impervious to crushing or kinking, but if you yank on it too vigorously when trying to stretch it out you'll start a separation of the spiral bands, and you'll have a leak. I know that now, but I didn't when I first got my Sprinter, and the tape and sealant I had patched it with just wasn't working anymore. I promise not to yank on my new green hose now that I know this, because it's not a fun job to replace it.
I jacked up the passenger side of my Roadtrek, blocked and supported it in a safe manner, rocked it to make sure it was stable on the jack stands, and crawled underneath. First order of business is to take off the protective sheet metal enclosure around the macerator pump by drilling out the four pop rivets that hold it on. This exposes the macerator and the green hose connection to it.
The green hose is stored in a nifty ABS molded enclosure that's directly under the Sprinter's diesel tank. Here you can see the hose leaving the macerator pump and disappearing onto this enclosure. It reappears out the other corner of the enclosure at the point where we're most familiar with it – the utility bay on the driver's side, by the propane tank, where we pull it out to dump. I didn't want to take this enclosure off to install the new hose, so I had to figure out a way to get the old hose out and the new hose in without taking the whole thing apart. I admit it – am old and lazy. I'd rather think than work any day of the week. My burning curiosity to take things apart for the fun of it flamed out long ago.
Here's my new hose, ready to install. the PEX hose type clamps came with it, and thanks to my previous work on my city water valve I had the appropriate crimper to install them. I unhooked the old hose from the macerator pump, and pulled out enough of it to allow me to get the end of the hose out from underneath the Roadtrek. It pulls out either end of the enclosure, we're just accustomed to pulling the other end out to dump.
Now here's my genius idea to avoid unnecessary disassembly and dreaded work – I'm going to attach the new hose to the macerator end of the old hose, so when I pull the old hose out the passenger side it will pull the new hose into the enclosure right behind it. I can fish it right through if I use the old hose as a pre-installed fishing line. I need a sturdy and not too bulky way to do a hose butt splice, and settled on Gorilla Tape. Here's a photo of the attachment – old hose on the left, new hose on the right. If it comes loose when I'm pulling it through, the end of the old hose will emerge with the tape flapping loose, and I'll have to do it the hard way.
I go around to the utility bay on the driver's side, and gingerly start pulling the old hose out, stopping frequently to make sure the new hose is feeding into the other end of the enclosure smoothly. It was a great relief to see the Gorilla Tape splice emerge, old faded hose on my side and bright green new hose on the other. Now all I needed to do is attach it to the macerator underneath and the discharge valve out here, and I'd be done.
These are barb connections at both ends, so you have to be really, really sure you're ready to put them together before you start pushing. The macerator end was easy, but I forgot to put the clamp over the hose before I pushed the hose onto the discharge valve. Luckily for me, I could unscrew the gray plastic elbow from the rest of the valve, and still get it on OK. Crimp these both on, and you are done.
Remember, folks, if you want your green hose to have a long and happy life, DO NOT PULL ON IT. If it doesn't quite reach the dump, push it back in and move your Roadtrek as necessary. Don't try to stretch the hose to reach. I also use a misting of silicone spray on the outside of the hose so it slides into and out of the enclosure easily.