All good suggestions to seal it up. I think the problem is the construction of the seam.
After taking mine apart with the help of an out of state AF dealer , I saw how the mfg. lapped the roof layers on their units.
The dealer offered a solution to the AF mfg. many times over the years, as he rebuilt the nose caps on a lot of his units. He changed the direction of the layering and sealed the edges of the filon before sealing it up.
After he did that, none came back leaking. As for his method of repair, it all fell on deaf ears as far as AF was concerned.
The downward slope of the AF cab-over roof allows water to gather at that seem when the unit is parked stationary.
Being that this is how most campers spend most of their life (parked) you would think the roof layers (shingles) would be lapped like a roof on your house, to shed water .
AF believes they should lapped in the opposite direction allowing water to shed while your driving in the rain at 60 mph .
Driving in the rain all of the TC's life , it would probably not delaminate . After you seal it you might want to consider moving to a wet climate and drive it 24/7 , they were designed to work that way . :)
Once the ends of the filon are penetrated by water its over.
The filon has a cardboard backing in order for it to bend. That cardboard like backing soaks up water like a sponge causing the glue to let go, the filon delaminates from the under structure.
Check your basement and firewall area, that's where some of my rain water settled. Some rolled along the basement frame area , out the back near the dump valves. Water collected at every horizontal area under the kitchen sink, along the outside wall.
****The AF common ground is located between the firewall and the water heater. You can see it in the drivers side corner of the camper if you use a small mirror and flashlight. This rusted and killed all my 12 volt power while on the road.
I connected the generator cable inside my empty generator compartment to restore my common ground to get things working again. It was a temp/perm fix because it worked ,it lasted and saved me from ripping out the water heater to get at that rusted ground.
The rest of the water soaked my mattress completely. I had the pleasure to sell it at a garage sale as a water bed to re-coop some of my lost money.
