Drill (buy on Amazon)
Wire brush attachment (Buy on Amazon)
Putty knife or old plastic card (Buy on Amazon)
Roof Seam Leak Fix
A common problem with our model Sprinter is the separation and rusting of the roof seam. Our van had a pretty significant roof leak that we did not notice until after we purchased it. The leak was so significant that any decent rainstorm could fill two 5-gallon buckets with water.
Cutting out the old material and welding in new material on our roof was not within our capabilities and seemed like overkill to have done professionally.
After a bit of research and weighing a few sealant options, we settled on using POR15 Patch "Filler and Seam Sealer". This seemed to be something that would seal the leak and also keep the rust development to a minimum. We have previously used POR15 products on other projects with success.
We first went over the seam with a wire wheel to remove any loose material. POR15 literally stands for "Paint Over Rust", therefor for the best adhesion you do not want to remove the rust entirely.
We filled the seam with the POR15 Seam Sealer and used an old plastic card to push the sealer down into the seam. Once the sealer cured, we painted over it with 3 coats for POR15 paint on both the inside and outside of the van.
Update: It has been over a year since we sealed the roof seam and we have not had any leaks!