Work done 2 yrs ago, heated garage, never out in the rain. the visual appeal of this car is a 10. As straight as they come. However, look at this picture. What would have caused this? Do I have a drainage issue? Any suggestions on repairing. I have bondo, glazing putty, acid etch primer, left over paint from original paint work. I am pretty talented with my hands, have sculpted etc... I also own an assortement of airbrushes, a compressor and a dremel. So if someone can help diagnos issue and tell me what to do and I can do it.
Exactly what panel is that?? It appears to be the bottom of a decklid or a door. >First--there appears to be some type of chaulk over that skin/seam...lots of chaulk will crack on its own over time..even if nothing is going on underneath it. >Second--being what I call a "tight area" it is virtually impossible to ever get those areas clean. Look at the OVAL drain hole to the L of the cracking chaulk. It looks like some rust at the very bottom of that opening...possibly an indication of what exists below that area. >If the cracking chaulk is in a spot BELOW that drain hole (as the panel is installed on the car) then any moisture naturally will accumulate down there. So, the drain hole becomes just an evaporation hole once water/moisture/etc gets below that level. >Short of dipping the part (complete immersion stripping/derusting) you may need to do some exploratory work and see what's under the cracking chaulk. Possibly, you could shoot something into that drain hole and attempt to stop the rust. No guarantees...POR15, etc MAY do it but all those products depend on being able to COMPLETELY SEAL OFF THE EXPOSED RUST from the atmosphere. >These "tight seams" (bottom edge of a 70-72 decklid for example) are always going to be problematic. I have seen rust repairs carefully done along the bottom of a decklid, top quality primers, etc used ....only to have the rust start bubbling up NEAR where the repairs were made later on. Not at the repair area but nearby along the same seam. >Does the outer skin show any signs of expansion/bubbling?
No--no need to apologize...regardless of which part it is it's apparent that it has something to do with an outer skin meeting an inner shell and the "tight spaces" that are a byproduct of this type of construction. You don't really have much choice other than to pick away at that area and try to treat whatever is under there. Again..FIRST TAKE A CLOSE UP LOOK at the door skin surface on the outside to look for any evidence of bubbling. If you see any on the outside then you know at some point you might dig right through the outer door skin. I would scrape away the chaulk and dig out as much rust as possible (if there's rust in there). After that I might put some zinc-rich paint in the cavity. Other ideas would include carefully swabbing the "cleaned" area with something like OSPHO ( using a QTip and not flooding it in there) and once dry (read the instructions) trying to seal it off with some sort of paint. You will need to really take your time using fine sharp picks, magnets, etc to get as much of the rust(if any) out of there. Don't use massive pressure with a pick, etc against the inside of the outer skin. Once done you will need to push that inner lip back flush with the door shell. Light tapping on that lip with a dolly on the outer door skin (covered with tape, etc to prevent nicks, scratches) to try and get it flush. Go slow and easy. No guarantees as rust in these areas is a real pain. Finally, the painted area just above the cracking chaulk appears to be pitted under the paint (maybe it's just the picture)...so this may have been a "problem" well before the car was repainted.
Disagree w/Patton on the phosphoric application.......you have to pour it inside the door and let it run all over the place....this will guarantee you get ample penetration in the rusting areas...apparently your door was never primed in that area and the moisture collects on unprotected metal causing rust. Soaking the area with ample amounts of acid will not hurt anything. Let the door soak overnight or a couple of days. Once rust is neutralized.....iron phosphate....it should not rust again. Wipe any area you can with acetone and then spray undercoating inside.......get the "professional" can from Autozone not the regular can. I have done this with great success and never had a problem.
