Originally written by luckysid1 on 2009-05-27 2:47 PM
Over the week end I drilled holes into the aluminum and took a tube and blew in a anti rust primer. Then filled the hole with a screw. Don't know how much coverage I got but it was something, I just hope the problem is checked. I'm afraid that your efforts were for naught. The proximity of the aluminum and steel has caused a galvanic reaction between the two dissimilar metals. Whenever two dissimilar metals touch, the softer of the two will suffer the most. Your white powder is active corrosion and a failure of the structural integrity of the aluminum sheeting. The only repair is the replacement of this metal. The only way to prevent any future damage, is to physically isolate the two metals from any electrical contact. You have a major reconstruction to consider, one that may exceed the value of your trailer. Gard | 
Steel touching aluminum
I have a steel framed trailer with aluminum skin inside and out. (Don't want to get into What Brand). It is a 2004. The aluminum is put on with two sided tape. There are spots where the aluminum is turning into powder. One of the spots is near a window. Last week end I pulled the window. There is no paint on the steel just rust. The rust was piled up in a corner of a joint and resting on the aluminum. From what I can tell, no paint or anything protecting the steel anywhere. I bought the trailer used and I really like it other wise. It looks like a very big job getting the aluminum off to paint trailer frame. If it took five years to show spots is this something that you just have to live with. any suggestions Is there any way this could make the trailer unsafe. Most of the spots are about the size of quarters. That would be a couple of dollars worth. 
