Our motor home is 2 years old and we have discovered what is best described as small pimples on the interior wallboard under the passenger window. I'm guessing there is about 100 of them that are 1/16" wide. Suspecting this is a water leak I removed the interior window trim and sprayed water on the roof and window looking for a leak and found nothing. What could this be? Thomas (Lodi, OH)
Thomas, you are probably correct; such marks are typically caused by moisture reacting with the glue on the wall panels. As a starting point, removing the window trim was the right course of action. If you are sure there is no source of water entry at the window or the roof above the window then the water is likely entering somewhere else and eventually seeping towards the window, where it finds its way to the inside of the coach. A good place to start a detailed inspection would be exterior moldings or trim pieces mounted close to the window. Inspect them very carefully for open seals, rusted mounting screws, etc. Also inspect the entry door seals and any other fitment attached to the sidewall that is at the same level, or likely higher, than the window. Remember, water seeks its own level, so the leak could literally be anywhere above the window. Excessive moisture can migrate laterally to a lower location before it is actually manifests itself. Water leaks can be extremely difficult to find and need to be caught early to avoid an expensive repair. Search meticulously and thoroughly and you should find it. RV repair facilities can be a last resort if you simply cannot locate the entry point of the moisture. Some will be equipped with ultrasonic devices that can locate water leaks in a relatively short time. If all else fails, take it to a pro shop. Be sure to use a sealant that is applicable to the material(s) you'll be applying it to once you located the source.