Slideout Roof Sealants
Dear RV Doctor:
We are new at this and are trying to do the best for our new motorhome. What type of sealing products would you use on the roof of a slideout?
Vickie Kennedy
Via email
For new motorhomes still under warranty, I heartily recommend doing nothing but keeping a close eye on all the seals, seams, and sealants around every penetration up on the roof — basically the entire exterior of the coach, including the roof portion of the slideouts. If there is any doubt about the integrity of any sealant, bring it to the immediate attention of the servicing dealer. Remember, that new coach is under warranty for at least a year. After the warranty period, the onus is on you for all future maintenance and upkeep.
Monthly or quarterly inspections are called for. Look for voids, gaps, cracks, etc. everywhere an attachment penetrates the roof or sidewall. Remember, every screw location is a potential water leak!
Be sure you know exactly which of the five or six types of roofing material you have. As I state in my seminars, the product you use must be applicable to the type of surface you are applying it to.
As far as sealants on slideout roofs, many manufacturers use a product called EternaBond; www.eternabond.com. Unlike caulking or lap sealant, it’s a smooth, flat tape containing a microsealing adhesive that you peel and stick. It’s important that nothing damage or impede the rubber slideout seals. The smoother, the better. Lumpy sealants or deteriorated caulking may cause some slideout seals not to fully seal. EternaBond is a smooth tape that eliminates that concern.
Waste System Worries
Dear RV Doctor:
The 3-inch gray-water waste valve on my motorhome was leaking badly. I did a little research and determined that both the gray-water and black-water waste valves should be replaced. After watching a couple of videos, this didn’t seem outside of my abilities. Boy, was I wrong!
The black and gray tank valves are exactly opposite each other, as in a mirror image, with a common “Y” fitting between them. After removing both of the old valves, I easily could install either of the new valves, but then the other would not install correctly. I kept dragging out one or both of the rubber seals when I tried to slide it into place. The spacing is simply too tight to work with while trying to hold the seals in place and line up the bolt holes, etc.
After many unsuccessful attempts, I cut out about a 2-inch section of the pipe between the black valve and the black-water tank (it was the easiest to access), thinking I could install a rubber coupler to make the pipe whole again. That also appears to have been a mistake. The coupler holds a seal as long as nothing moves, but applying even the slightest movement makes it leak like a fire hydrant.
How badly have I damaged my motorhome, and what’s the best way to make a permanent repair? Is it even salvageable?
David Rasmussun
Via email
I’m sure your waste system is indeed salvageable. And, yes, it can be quite challenging to replace either tank valve when they are configured like that. Many coaches have that setup.
As the situation stands now, you’ll likely have to use some ABS cement to attach a simple coupler and a short piece of 3-inch pipe to replace the portion you cut out in order to install the connector. Be sure to use a Calder-type coupler with thick sidewalls. Get that part of the “Y” back to what it looked like before you started.
You’ll notice that at each tank outlet, a clamp secures the pipe into the molded outlet fitting. With one of the valves removed, the trick is to push the whole assembly deeper into one of the outlets, thereby creating a slightly larger gap between the adapters where the valve will be placed.
First, though, secure the seals to each valve by using light grease; I recommend Dow Corning’s Molykote 111 Compound. The grease will help hold the seals in place as you insert the valve between the two ABS adapters. This can be tedious, since there’s a rim on the adapters that the seal must encompass.
Once the valve is inserted to the proper orientation and the seals are in place, pull the assembly slightly out of the tank outlet in order to install the four bolts that sandwich the valves. Before proceeding, open and close each valve a few times to ensure they slide properly and the seals have not become distorted.
With both valves installed, you should be able to slide the complete “Y” assembly an inch or so, back and forth, deeper into one tank outlet and shallower into the other tank outlet. Center the assembly between the tank outlets and secure each with new hose clamps. You should also apply some pipe sealant around each portion of piping that slides into each tank outlet. The whole assembly will likely rotate up and down, so you’ll have to secure those clamps enough to keep it tight and stable. Perhaps even install a brace of some type to keep the assembly secure.
Now, run some clean, fresh water into each tank and check for leaks. If you see any drip at all, it might be necessary to start all over, but if you’re careful, you’ll accomplish the task just fine. Just take your time and don’t be stingy with the pipe sealant.
A follow-up from David Rasmussun:
Well, I believe a successful repair has been made. To begin with, the waste pipe attachment at the tank outlet was as you described. However, that sucker wouldn’t budge even after I applied the largest set of slip-joint pliers available. I was afraid of cracking the tank if too much torque was applied, so I abandoned hope of moving the pipe at that end.
Instead, I purchased a new fitting that connects to the waste valves, and I glued in a new section of pipe that closed the gap to the tank pipe end to within 1/8 inch. (The previous gap was about 2 inches wide.) To close that gap, I installed the rubber coupler that is covered with a metal “skin” and tightened with two hose clamps at either end. The skin provides rigidity, and the whole thing is now leak-free and appears to be vibration-resistant. I’m cautiously optimistic that my waste-water system problems are (for the time being) a thing of the past. I still need to replace the section of sheet metal I destroyed while gaining access to all the parts, but if I’m lucky, I’ll be able to keep the total cost under $200 and 20 man-hours.
Tesla Towing
Dear RV Doctor:
Shipments of the new Tesla Model 3 are expected in late 2017. Can any Tesla vehicles be flat towed behind a motorhome?
Kaleae Groene
Via email
Tesla does not recommend flat towing any of its vehicles behind a motorhome. It has to do with the fact that the drive axles are never disconnected from the engine. Perhaps in the future an aftermarket supplier might come up with a modification, but for now, the only way to tow a Tesla is on a trailer.