My 5th wheel is winterized. I used compressed air and blew out the water in the lines but I did not get the cover on for winter. I live in the Northwest, so rain and snow are a sure thing. I’ve found that my RV’s sealed underbelly is collecting a small amount of water. Is this a leak in the sealed underbelly? I turned to YouTube for ideas on how to look for leaks and found a video on how a dealership in PA places a positive 2-3 psi on the inside of the trailer then soaps the outside looking for leaks. Have you ever heard of such a process? Do you know if this is a good or bad idea? Your thoughts, please. Thank you. —Mary
The process you are describing is probably from a machine known as Sealtech. This is a machine that draws air from an outside source such as a roof vent or a side window and pressurizes the inside of the rig. The theory behind it is that a slight pressure inside the rig would cause air to escape out of any leaks or cracks around the rig. Spraying the outside with a soapy water solution would create bubbles where the air was escaping, similar to finding a nail or leak in a tire. The pressure is adjustable as larger rigs would require slightly more pressure to fill the rig and smaller ones would not want the high pressure as it could push out a slide room.
The most accurate way to find leak in sealed underbelly
We conducted a series of videos years ago at a local dealership and it was amazing how many leaks we found on a new unit. This method is the most accurate leak detector, as some of the leaks can actually come into the rig in an area away from where the leak shows up on the inside. Leaks are one of the most difficult issues to find as water can travel along hollow tubes used in the frame and other paths. The Sealtech machine finds the outside entrance source other than the old fashion way of soaking the outside of the unit down and searching the inside for moisture.
According to the locator on the Sealtech site, there are several locations in the Northwest from Eugene, OR, all the way up to Seattle, WA.
However, before you take it into a dealership, keep in mind the leak in your sealed underbelly could just be a corrugated piece of plastic covering the tanks and/or drain lines and using the Sealtech machine would not identify the leak. You would need to remove the material and visually inspect what might be leaking. It could be something as simple as water running off the roof along the sidewall or back wall. You might find a small crack or hole in the material running along the flat material to another crack or opening. I would take a look at what the bottom layer of your rig is constructed with first. If it’s a hard basement-type construction, then find a service center.
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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