Removing coroplast on Sprinter

boxcar · 08-21-2021, 10:35 AM

I bought a 2018 297FWRLS 33' Sprinter in 2018 and have gone through the usual set of problems and fixes. Two days ago we got back to the camper after several hours and found the toilet had been running and overflowed onto the floor. I "always" shut off the water supply before leaving.

I can't tell how long the toilet was running but there was only a bit of water on the floor to clean up.

I have the Theford Model 42072 porcelain toilet. It kept running during a few tests until I switched over to the water pump, making me think it was related to water pressure. Back on city water now and the toilet is behaving.

Figuring that there may have been a lot of water that went somewhere, I crawled under and saw that the coroplast is bulging some, but there doesn't seem to be any water in it now. The insulation that I can get to in the holes next to the plumbing in the basement is wet, however, so I believe the water got there.

We're temporarily living in the camper and I'll likely need to stay in it into winter because of medical issues and proximity to the hospital. We're camping at 7000 ft on the front range in Colorado so it's going to be cold.

I'm sure I need to drop the coroplast and dry out the insulation at the very least. I know I'll need to look for floor damage.

I'd appreciate any advice before I start on this project. While it doesn't look like I need much in the way of tools. I don't have a lot of tools here. It looks like I'll have to drop the gas line all the way along one side and cut around the spray insulation.

I see that I can buy coroplast at Home Depot in case I have to replace it. Anything else I should do before I go in?

I plan to put some type of skirting around the camper and use something to keep it from freezing underneath.

Thanks!

bobbecky · 08-21-2021, 04:44 PM

If you don't feel the weight of water on top of the coroplast, I would just leave it alone and it will dry out just fine. Usually, all there is for 'insulation', is a thin layer of bubble wrap material. A better project would be replacing the toilet with a Dometic model. I replaced our Thetford about 7 tears ago with a Dometic 310, and have not had to replace anything on it, and we full time, and it holds water in the bowl. The Thetford was a problem early on, and nearly flooded the trailer late one night when the pedal broke. I replaced the pedal, but it was never good after that and the replacement Dometic at about $200 at that time was money well spent.

gearhead · 08-22-2021, 05:41 AM

This time of year I would think you have low humidity at 7000 ft. Rather than drop all of the chloroplast I would start on the side opposite the gas line. Drop one side and see if it dries out. Be prepared for some of the screws to break off. I would also get some self drilling/self tapping screws of the same size as the OEM to re-install. Also some lage fender washers to help hold the chloroplast better.
I've always used a small 20volt impact gun to run the secrets in. I guess if you go back in the original hole you could use a ratchet.
All this is assuming they used screws originally. I haven't dealt with the "nails".

**JRTJH** · 08-22-2021, 06:07 AM

An "easy way" to dry out the space between the floor and the coroplast is to put a "floor drying fan" (the small type used in bathrooms in restaurants, etc) at one end with a "home style duct" made from a dryer vent pipe and duct tape to attach it to the fan opening. Remove 3 or 4 screws from the end of the coroplast and insert the dryer vent pipe into the "basement". Then remove several screws and put a couple of "1x4 spacers" (cut from a spare 1x4) to "prop open the end of the coroplast"...

Turn on the fan, it will blow air into the "basement" and with the opening on the other end of the trailer, will push all the "wet air" out of the space. After a couple hours, check to see if there is any remaining moisture. Sometimes it takes a day or two, depending on the amount of standing water, to completely dry the space.....

IMO, this definitely is easier than removing large sections of coroplast, which seldom go back up the same as they were before removal.

boxcar · 08-22-2021, 11:59 AM

Thanks for the suggestions. I crawled under to drop the coroplast on one side but found out those hex-headed "screws" are actually nails. At least, they don't respond to my impact wrench and turn freely.

Some are 5/16 and others are larger but star instead of hex. I've never seen a fastener with a head like that. I have a cutoff tool with a diamond blade on it so I will cut some of the heads off after I buy some self-tapping screws and fender washers. I'll try to find a fan and put in a duct port and drop other end.

I noticed that there was a bulge over the axles 12' behind the basement so I cut a couple of holes there and drained out 4 gallons of water. The coroplast is one very large sheet.

I checked to make certain I'd put on a water regulator - I had. My dial regulator shows 80 at the spigot. The inline regulator is supposed to be 40psi. Either the regulator is bad or the toilet won't reliably hold against that low a pressure. I'm onboard with the suggestion of replacing the Thetford with the Dometic. Any idea of the difference between the Dometic 310 and 320 series? I was about to put on a bidet so I'll do it all at the same time.

The humidity IS low here so I just need to make sure this dries enough before a freeze - I likely still have a couple of months. I'll find a fan and try to leave it running for a few days.

Thanks for the suggestions!

gearhead · 08-22-2021, 04:53 PM

John's fan idea is great. If there's a Harbor Freight store nearby they may have one.
https://www.harborfreight.com/search?q=fan
If you get everything fixed and the chloroplast is all screwed in and sagging, I have used 1 1/2" X 1 1/2" sheet metal angle to reinforce the chloroplast. I cut to the width of the frame rails and hold it up with a 1/4" bolt and nylock nut.

behrmr · 08-23-2021, 09:54 AM

Quote:

Originally Posted by boxcar

Thanks for the suggestions. I crawled under to drop the coroplast on one side but found out those hex-headed "screws" are actually nails. At least, they don't respond to my impact wrench and turn freely.

Some are 5/16 and others are larger but star instead of hex. I've never seen a fastener with a head like that. I have a cutoff tool with a diamond blade on it so I will cut some of the heads off after I buy some self-tapping screws and fender washers. I'll try to find a fan and put in a duct port and drop other end.

I noticed that there was a bulge over the axles 12' behind the basement so I cut a couple of holes there and drained out 4 gallons of water. The coroplast is one very large sheet.

I checked to make certain I'd put on a water regulator - I had. My dial regulator shows 80 at the spigot. The inline regulator is supposed to be 40psi. Either the regulator is bad or the toilet won't reliably hold against that low a pressure. I'm onboard with the suggestion of replacing the Thetford with the Dometic. Any idea of the difference between the Dometic 310 and 320 series? I was about to put on a bidet so I'll do it all at the same time.

The humidity IS low here so I just need to make sure this dries enough before a freeze - I likely still have a couple of months. I'll find a fan and try to leave it running for a few days.

Thanks for the suggestions!

I just recently watched a YouTube video of a black tank repair where the coroplast needed to be removed. The technician literally just pulled the nails out with a pair of channel locks. Then when he replaced them he used self tapping screws.

bobbecky · 08-23-2021, 10:14 AM

The 310 is a round bowl and the 320 is an elongated bowl. Those ‘regulators’ that they sell that are about 3” long and just screw inline with the hose are really just restricters and don’t work well. You would be better off with one of these that are a real regulator. https://www.etrailer.com/RV-Water-Pr...01-1117VP.html

Scttw · 08-23-2021, 10:30 AM

I knew when I started to read this post you would find the water on top of the blanket.

Most toilets are designed that if filled too high they overflow underneath instead of throughout your trailer. Depending on what is in there for insulation, I'd replace the wet stuff with fresh, cut a 2 foot x 2 foot access trap door and then just tape it back up.

**sourdough** · 08-23-2021, 11:37 AM

Quote:

Originally Posted by boxcar

Thanks for the suggestions. I crawled under to drop the coroplast on one side but found out those hex-headed "screws" are actually nails. At least, they don't respond to my impact wrench and turn freely.

Some are 5/16 and others are larger but star instead of hex. I've never seen a fastener with a head like that. I have a cutoff tool with a diamond blade on it so I will cut some of the heads off after I buy some self-tapping screws and fender washers. I'll try to find a fan and put in a duct port and drop other end.

I noticed that there was a bulge over the axles 12' behind the basement so I cut a couple of holes there and drained out 4 gallons of water. The coroplast is one very large sheet.

I checked to make certain I'd put on a water regulator - I had. My dial regulator shows 80 at the spigot. The inline regulator is supposed to be 40psi. Either the regulator is bad or the toilet won't reliably hold against that low a pressure. I'm onboard with the suggestion of replacing the Thetford with the Dometic. Any idea of the difference between the Dometic 310 and 320 series? I was about to put on a bidet so I'll do it all at the same time.

The humidity IS low here so I just need to make sure this dries enough before a freeze - I likely still have a couple of months. I'll find a fan and try to leave it running for a few days.

Thanks for the suggestions!

The 310 is round and does not have a lip at the top of the bowl so the water jets are on the surface and shoot sideways around the bowl. The 320 has a lipped elongated bowl and the water comes out under the lip. The cutout distances are different and are probably different from the Thetford. Depending on how your Thetford is located that might be an issue or not. I've replaced 3 Thetfords with Dometic 310s with no issue. Some of the Thetfords have a cutout that is 8" from the wall to center, the 310 is 10" and the 320 is 11" as I recall - just measure to be sure.

boxcar · 08-23-2021, 12:52 PM

I picked up necessary materials at Lowes last night and spent about 45 minutes putting it all together.

I bought a 1/4 HP 3 speed 925CFM floor fan, a 6x7 square to 6" round HVAC duct adapter, a 12"x4" to 6" register adapter, and a roll of foil tape.

I also needed a dansko shoe box, but my DW provides an endless supply of those.

The coroplast is held on with self-tapping machine screws across the front and the back so I pulled all the screws across the tail. I cut a three-sided rectangular hole up front behind the spare tire the shape of the 6"x7" square and folded the coroplast back, inserted the adapter and pushed the tabs down, then taped it all with foil tape.

I put the 12"x4" rectangular register vent over the mount of the floor dryer leaving a 2" gap on one end and taped it all up with foil tape. I had purchased some flexible vent hose and a male/male 6" adapter but discovered that I only need to raise the blower 4" with the shoebox to mate the two adapters.

The fan is blowing on low speed with a good breeze blowing out the tail of the 5er. The fan has a timer on it so it will shut itself off periodically.

I expect I could have just let it dry out but I'll sleep better knowing that the moisture is evaporating quickly now.

Invaluable help from the forum members! Thanks again!

Scttw · 08-23-2021, 01:07 PM

Nicely done!!!!!!!

boxcar · 08-24-2021, 10:44 AM

Quote:

Originally Posted by bobbecky

The 310 is a round bowl and the 320 is an elongated bowl. Those ‘regulators’ that they sell that are about 3” long and just screw inline with the hose are really just restricters and don’t work well. You would be better off with one of these that are a real regulator. https://www.etrailer.com/RV-Water-Pr...01-1117VP.html

I have one of those but was using the inline at the time. Proves your point!

boxcar · 08-24-2021, 10:46 AM

Quote:

Originally Posted by sourdough

The 310 is round and does not have a lip at the top of the bowl so the water jets are on the surface and shoot sideways around the bowl. The 320 has a lipped elongated bowl and the water comes out under the lip. The cutout distances are different and are probably different from the Thetford. Depending on how your Thetford is located that might be an issue or not. I've replaced 3 Thetfords with Dometic 310s with no issue. Some of the Thetfords have a cutout that is 8" from the wall to center, the 310 is 10" and the 320 is 11" as I recall - just measure to be sure.

My Thetford is mounted diagonally into a corner so there should be room for either. I haven't yet decided on which to buy.

tomd · 08-29-2021, 07:32 AM

On our Sprinter the water tank 'dropped' so I had to remove most of coroplast. The hardest part was removing the original fasteners. They are shot in, not really screws. I used small vice grips to twist them loose, and then pried them out. I suggest throwing them out and replacing with screws!!

Coproplast was not expensive, and I replaced the insulation with foil insulation, and used self tapping screws; all found at local builder supply. Suggestion: Look at screws holding tank frames... replace with bolts. My screws failed, easy fix to use bolts instead. Black duct tape or gorrilla tape helps a lot for seams. I made cut out areas near valves, fittings for future inspections. Just some thoughts...

Third Degree · 08-29-2021, 08:04 AM

I have been using an adjustable water regulator with very good results. I up mine at 50 psi and it gives enough pressure inside the RV. I do not believe there is an on board water regulator in the RV. Also you might get a heated water hose now since the cold is coming. Also get some pipe insulation for any exposed areas. This is the regulator that I have been using with good results.
https://www.amazon.com/Twinkle-Star-.../dp/B07P94MQ68

rlh1957 · 08-29-2021, 08:20 AM

Cut it with a razor knife where you need to work. Save the piece and tape it back with black 2” or 3” gaffers tape.
Gaffers tape works better than duct tape, and the adhesive doesn’t turn to goo.

GMH · 08-29-2021, 11:31 AM

I removed two large sections of mine so I could replace all the heat ducts. I re-used the original #14 self tapping screws and fender washers all around the perimeter. For where I made my cuts, I got a 3-1/2” wide strip of .075” aluminum the width of the frame and screwed it in place (#8 self tappers) above the coroplast about 8” on center. After it was in place, I removed the screws one at a time, drilled the hole out to 3/16” and used a 3/16” aluminum pop rivet and homemade fender washer.

W5WI · 08-29-2021, 12:00 PM

Quote:

Originally Posted by boxcar

I bought a 2018 297FWRLS 33' Sprinter in 2018 and have gone through the usual set of problems and fixes. Two days ago we got back to the camper after several hours and found the toilet had been running and overflowed onto the floor. I "always" shut off the water supply before leaving.

I can't tell how long the toilet was running but there was only a bit of water on the floor to clean up.

I have the Theford Model 42072 porcelain toilet. It kept running during a few tests until I switched over to the water pump, making me think it was related to water pressure. Back on city water now and the toilet is behaving.

Figuring that there may have been a lot of water that went somewhere, I crawled under and saw that the coroplast is bulging some, but there doesn't seem to be any water in it now. The insulation that I can get to in the holes next to the plumbing in the basement is wet, however, so I believe the water got there.

We're temporarily living in the camper and I'll likely need to stay in it into winter because of medical issues and proximity to the hospital. We're camping at 7000 ft on the front range in Colorado so it's going to be cold.

I'm sure I need to drop the coroplast and dry out the insulation at the very least. I know I'll need to look for floor damage.

I'd appreciate any advice before I start on this project. While it doesn't look like I need much in the way of tools. I don't have a lot of tools here. It looks like I'll have to drop the gas line all the way along one side and cut around the spray insulation.

I see that I can buy coroplast at Home Depot in case I have to replace it. Anything else I should do before I go in?

I plan to put some type of skirting around the camper and use something to keep it from freezing underneath.

Thanks!

Home Depot Coroplast is white. You can purchase the black at Shapes Plastic. Seems like a reasonable price with free shipping.
Go to: https://shapesplastics.com/4-black-c...BoCgEgQAvD_BwE

firestation12 · 08-29-2021, 01:41 PM

Quote:

Originally Posted by boxcar

Thanks for the suggestions. I crawled under to drop the coroplast on one side but found out those hex-headed "screws" are actually nails. At least, they don't respond to my impact wrench and turn freely.

Some are 5/16 and others are larger but star instead of hex. I've never seen a fastener with a head like that. I have a cutoff tool with a diamond blade on it so I will cut some of the heads off after I buy some self-tapping screws and fender washers. I'll try to find a fan and put in a duct port and drop other end.

I noticed that there was a bulge over the axles 12' behind the basement so I cut a couple of holes there and drained out 4 gallons of water. The coroplast is one very large sheet.

I checked to make certain I'd put on a water regulator - I had. My dial regulator shows 80 at the spigot. The inline regulator is supposed to be 40psi. Either the regulator is bad or the toilet won't reliably hold against that low a pressure. I'm onboard with the suggestion of replacing the Thetford with the Dometic. Any idea of the difference between the Dometic 310 and 320 series? I was about to put on a bidet so I'll do it all at the same time.

The humidity IS low here so I just need to make sure this dries enough before a freeze - I likely still have a couple of months. I'll find a fan and try to leave it running for a few days.

Thanks for the suggestions!

A word of caution, since you mentioned wanting to install a bidet. I recently changed out my 310 (regular bowl) for a 320 (elongated bowl) and added a bidet. The 310 has a removable cover at the back of the bowl, the 320 has a permanent ceramic hump at the back of the bowl, that made the installation of the bidet a little more difficult. The base of the bidet contacted the hump that hides the backflow valve of the 320 toilet which denied the 3/16" of an inch that the bidet base needed to correctly fit. I was able to remove a small portion of the bidet base to make the installation work. Measure carefully before committing yourself to the project. In the end, I'm happy with the results. By the way, those "nails" that attach the coroplast don't come out very easily. I wore out 2 pairs of vice grip pliers in the process of removing about 50 pins.

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