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RV Doctor ColumnRV Doctor #304 Dear RV Doctor, my RV has a 50-amp, four-prong shoreline cord. According to the wiring inside the RV going to the emergency management system, it should be a 50-amp, 240-volt system. The people I bought it from keep telling me it's only a 30-amp, 120-volt service. It does have a 120-volt adapter with it. It has a Line 1 and a Line 2 coming into the EMS system. I'm pretty sure that I'm right about it being a 240-volt system. Also, in the Owner's Manual, it states that this coach has a 12-volt inverter system. But the batteries, of which there are five, are 6-volt each. Is this correct or should there be 12-volts per battery. I do have two 12-volt batteries next to the inverter compartment. I believe these batteries are the starting batteries for the engine (this is a diesel pusher coach). In the first compartment I have my inverter, in the compartment to the right of this are the two, 12-volt batteries. In the next compartment is one, 6-volt battery and then there are four more, 6-volt batteries. All four of these batteries are wired in series. The one lone 6-volt battery, I have no idea what it might be for. John W. Tittle, (Nauvoo, AL) John, Indeed a four-prong shoreline cord is indicative of a 240-volt, 50-amp service. Actually you have two legs of 120-volts AC at 50-amps. The EMS along with the power distribution panel splits the coach electrically and supplies 120-volt AC service along two paths. But don't let this confuse you. If the campground does not have 50-amp service, the adapter is used but the available park power is limited to 30-amps maximum. The EMS again monitors your current usage and will shut down circuits if the 30-amp limit is realized. Your other question concerns the DC circuits. The actual usage of the direct current is 12-volts and with the 6-volt batteries wired in series, you have 12-volts being supplied by the batteries and used by the inverter to invert to AC when necessary. Why you have an odd 6-volt battery mystifies me also, unless it is a spare of sorts. You may want to trace the cables and see exactly where they go. Dear RV Doctor, while doing some cold weather camping I seem to have developed a leak where my piping from the gray water dump valve attaches to the gray water tank. I'm assuming that the water froze in there while I was camping. On inspection I noticed a large glob of some black material covering this connection. There is no "glob" (and no leak) on the black water tank fitting, which leads me to conclude that someone may have tried to repair this once before. Is it possible to repair a fitting of this kind? This is an older RV and I don't want to replace the tank if I don't have to. Patrick Bergin, (Ashburn, VA) Patrick, it's quite possible that "glob" you mention has actually been there from the start. Oftentimes, during production, a thick sealant is used at that juncture where the outlet pipe actually attaches to the tank outlet. Over time and after experiencing the extremes of the seasons, the sealant can ooze out a little around the opening. Perhaps some overly energetic installer applied a bit too much "glob" to that one tank during construction exasperating that ooze, so to speak. The fact that a leak has developed at that point is probably attributable to the expansion and contraction of the plastic components and the movement of the sealant over time and varying temperature exposures. Or you may be correct in thinking there was a prior attempt to repair a leak; it happens easily at the outlet of tanks, especially if the drain plumbing is not supported properly. Not a huge worry either way. Begin by completely flushing and emptying that gray tank. Disassemble the termination valve assembly at that tank by removing the four mounting bolts. Loosen the clamp positioned around the outlet opening and carefully wiggle and rotate the drain pipe as you pull it out of the tank. Thoroughly clean the pipe and the lip of the outlet and inspect the outlet for damage. Cracks can develop easily at the outlets of holding tanks. This is one of the most vulnerable points. If the termination assembly and subsequent plumbing is allowed to "bounce" or move in any direction, a crack could result. Be sure to add adequate support for the weight of the pipes and fittings attached to each tank. If you are sure there are no cracks at or near the outlet of the tank, apply a generous amount of soft piping sealant such as Rect-O-Seal, to the outlet pipe. Be sure to use a new clamp and secure it properly about 1/2" from the end of the outlet opening. Reinstall the dump valve and all other plumbing. It's a good idea to clean and lube the valve since you have it out. Also inspect and replace the "O" rings on either side of the valve if they appear to be dried out or damaged in any way. Now if you indeed find a crack at or near the outlet of the tank, it may be necessary to have it professionally welded. In most cases, cracks or holes in any thermoplastic such as ABS or polyethylene, (the most common plastics used for holding tanks), can be effectively repaired by welding. Some patches may work for the short term, but a permanent fix is secured only by plastic welding. After any repair, be sure to flood the tank to a level above the repair with fresh water and carefully check for leaks around the opening. Take your time and the results should prove effective. Dear RV Doc, I have an older Class C motorhome. There has been a leak around the seams of the cabover bed. I have removed them and was looking for some kind of putty or sealant to seal it off when I put the metal strips back on. It looks like the manufacturer used some kind of putty strip about ¾-inch wide, then screwed the strips in place. Where could I find such an item or something that would do the job well. Ronnie Lee, (Carlsbad, NM) Ronnie, indeed, the 3/4" wide putty tape was the sealant of choice for many years under all the seams and fixtures attached to the roof of the RV. Problems arose when no other protection was used to seal the putty tape. The putty tape was helpful against leaks caused by installing mounting screws or other hardware, but seldom did it last unless coated over with a roof seal coating of some type. It was prone to dry out over time, shrink and crack with the extremes of varying temperatures and simply needed yearly attention. But as technology has improved in other areas of recreation vehicles such as electronics and hydraulics, so to has the technology of sealants. At the fore is a company called Eternabond, makers of an assortment of roof repair and sealing products. For your particular application, I would recommend their DoubleStick to be used between the roof and the metal strips followed with an overlay of Eternabond's WebSeal. The only preparation necessary is that the surfaces be clean, dry and free of any remnants of silicone. Silicone is the only thing Eternabond will not stick to. Eternabond products will remain flexible to minus 70 degrees F., which means it will stay stable even under bombardment of UV rays. Plus it is so easy to install. Just simply roll it out and press it down. Quite simple, no mess, very little prep, no clean up and Eternabond will stick to just about any type of RV roof including EPDM. Just be careful you have it where you want it. It is virtually impossible to "un-remove." Ask your dealer about Eternabond products, or visit them on the web at www.eternabond.com.
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