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RV Doctor ColumnRV Doctor #350 Hey Doc, I just purchased your book, The RV Owner's Handbook; thanks for the wealth of information. I own a 27-foot recreational vehicle and am about to embark on the "spring shakedown" and want to recaulk any external caulk with possible cracks or leaks, etc. I note you indicate remove all old caulking which would be a daunting task in terms of end caps, side molding, roof vents, etc. Can one simply clean the old caulking with denatured alcohol or some other product and then recaulk? How does one tackle such a task? Thanks much, Mike Bengs, (Roseburg, OR)
Mike, in my opinion, the crucial location where it's important to remove all remnants of the old sealant is the roof area, specifically the perimeter and any seams. This is especially true if the existing sealant appears to be flaking. For trim moldings, compartment doors, windows, running lamps, etc., it's not as critical, but aesthetics there, are important. Take a look at the ugly-looking sealing job pictured here. Even though this awning rail may not leak, it certainly can be made to look a lot better. On sidewall components such as windows, for instance, you'll still want to trim the existing caulking carefully with a razor knife and slant the blade slightly in to create a small cavity of sorts. Then apply a new bead of silicone or like sealant. Just a small bead is all that's necessary. Wet your finger and press the new sealant into the cavity you created with the angle of the knife blade. In some cases I recommend taping off the area to keep excess sealant pressed out by your finger from spreading too far. If you trim the nozzle of the silicone tube very small, however, it can be done with less preparation. Neatness isn't as critical up on the roof. Be sure to work the sealant in to all the cracks and crevices. If, however, the old sealant has become brittle and is flaking or peeling off, then it will be necessary to remove all of it and start over. In those instances, I would also remove the roof vent itself and put fresh butyl tape under the flange and re-secure it to the roof. The same process should be repeated for all components secured to the roof. And keep in mind, the type of roof, (aluminum, fiberglass, EPDM, etc.) will dictate other specific guidelines.
Dear RV Doc, we are shopping for a used motorhome and would love to have some guidelines for how long major components should be reasonably expected to last. Recognizing that there will always be wide variations because of usage levels, maintenance done and how many hours in campgrounds with poor voltage, etc., how long might refrigerators, air conditioners, generators, awnings, water heaters, water pumps, etc., last? We're looking at a seven year-old Damon with only 23,000 miles on the chassis and 107 hours on the generator. But we wonder how much we might have to spend over the next couple of years. Should the roof air conditioner likely be good for a few more years or should we just replace it now even though it works? Ditto for the other bigger-ticket items. Keith Bryan, (Grant, FL)
Boy Keith, that's like asking how long is a piece of rope! But at least you did phrase your question in context. I'm of the opinion that, when cared for properly, RV components can last a long, long time. Regular preventive maintenance practices can really prolong the useful lifespan of just about everything on the coach. How long? Like you stated, it depends on the treatment it has received during its life. I am personally wary of LP burning appliances approaching eight or nine years of age. Some components do wear out over time. One hundred hours on the generator is not outlandish, however. I've always said non-use is worse than abuse in many cases. With any used RV I would heartily recommend that a pre-delivery inspection, (PDI), be performed on all the components in and on the motorhome prior to signing on the bottom line. This procedure will reveal compelling issues which can then become a bargaining chip for negotiating the final price. I'm also of the opinion that just about anything can be repaired or at worst, replaced if need be. But I would never replace a major component until absolutely necessary. A seven year-old unit is not that old, (right now!), especially with such low mileage. So I would think your chances are good that most everything will be in working condition as it stands. But again, a thorough PDI will reveal any shortcomings with the LP appliances and the major systems. Consider it cheap insurance to PDI the rig prior to taking ownership.
Dear Doc, I am having a problem draining the black water holding tank on my coach. After opening the valve it drains normally until the tank is approximately half empty and then stops flowing altogether. However if I unhook the drain hose it will continue to drain until almost completely empty. I don't understand why I have to unhook the drain hose to completely drain the tank or how to resolve the problem. Any ideas or suggestions? David Badger, (Falls Church, VA)
David, barring any severe blockages inside the holding tank, it is apparent a venting problem exists. As a holding tank drains, air must enter the tank from above. All holding tanks must be vented through the roof of the RV. In some cases, the vent pipe can become dislodged and fall down inside the tank, submerging itself in the contents of the holding tank. This effectively blocks off the vent, thereby prohibiting the venting action of allowing air to enter as you try to empty that tank. This is why it seemingly drains normally if you unhook the drain hose. Disconnecting the sewer hose allows air to enter the tank. Here's an analogy..place a drinking straw into a glass of water. If you simply lift the straw out of the glass, the water inside the straw drains out as you lift. Now place your finger over the open end of the straw and lift it out. The water remains trapped inside the straw until you remove your finger from the end. Liquid entering the holding tank must displace the air when draining into the tank and air must enter behind the contents during draining of the tank itself. That vent through the roof must work in both directions. Here's how to check it out. From up on the roof, remove the cover for that holding tank vent. If the ABS piping is not protruding above the roof a couple inches or so, chances are the vent has slipped down into the tank and made contact with the contents. In some cases, you can re-attach it correctly from inside the RV; in other cases, the holding tank must be dropped in order to repair that vent connection. A thorough inspection will reveal the best method of repair.
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