I bought a used FD, when I replaced the battery I noticed lots of corrosion on the bolts holding the battery tray in the car as well as the corrosion has partially eaten through the crossmember running beneath the battery tray and has left a trail along the car's subframe up front.

I noticed that the air conditioning lines that run under there have some corrion on them as well, or some surface rust. Maybe a little of both.

I cleaned up the bolts, replaced the battery with a new one and re-installed. Today I removed the battery for some maintenance and noticed the two bolts that attach to the frame were covered in that white corrosive powder, as was the frame and the crossmember below the battery.

The battery isn't leaking, so what could cause this? Could it be the AST, the A/C Lines??

Any suggestions are very well appreciated.

Thank You

 

you need to clean it up with lots of baking soda and water. Clean all that up completely and go from there. The baking soda neutralizes all the battery acid so the corrosion doesn't come back. That doesn't sound like a/c at all, coolant maybe depending on what it looks like.

 

That is typical of battery-acid corrosion. Acid "breathes" out from non-AGM vented-to-air lead-acid batteries as they are charged and gets on everything nearby. Just clean it up as described above and repaint.

 

That crossmember is pretty easily replaced....IIRC just 4 bolts and a few clips.
FWIW, whenever I remove the battery for anything, I give the bolt holes and bolt heads a quick spray of terminal protector grease.