I know there are alot of posts about how to prep sheet metal rust and what chemicals could be used but most seem outdated I never found a straight forward answer...maybe someone can enlighten me on the topic: I have a good bit of surface rust on the trunk floor of my '66 Special, along with holes I just recently found where the floor pan connects to the wheel housing on both sides, and these appear to be the only areas where the rust broke through. I checked all over with a screw driver for weak spots but did not find any. I also discovered a gallons worth of debris, which I vacuumed out, stuck between the trunk floor pan and the rear of the quarter panel, which most likely explains the rust popping through on the exterior as it just sat in there retaining moisture. First off, how difficult and/or costly of a repair is it to fix the seam between the floor pan and the wheel housing? I'm not an expert, but I did work at an auto/body shop through high school and it looks like the metal will have to be replaced where the two panel meet (and I want it done right so no fiberglass patches). ---- In the mean time, I would like to at least stop the rest of the surface rust in the trunk, as I live in south Louisiana so it's going to get worse before it gets better. The basic steps as I understand them is to degrease / de-wax the surface, remove loose rust with wire wheel or brush, prep the rusted metal with an etching solution (phosphoric acid?), seal with an epoxy primer, then paint. Is this the correct process and is this what the POR-15 kits basically provide? Or recommendation for other products? From what I have read, POR-15 isn't to be used on surfaces exposed to sun light or that need to look nice, such as exterior body panels (it can't be painted over?). What would you use in these situations to deal with rust? Sorry for the long post but this seems like a tricky, messy job to do correctly so I want to do it right the first time. Crawling in a trunk in 100 degree heat isn't my idea of fun! Thanks!
You pretty much have it figured out. Get a 4" angle grinder with a wire wheel and just go to town on that floor to get the surface rust off. That will give you the clearest look at where you are. As to the rusted out part, you can either find a donor car in the junk yard, buy new trunk floor pieces, or just get some flat sheet metal and hammer and cut it to fit the bad areas and weld it in. Phosphoric acid, metal ready, metal blast and various other acid type solutions will eat off the surface rust, I wouldn't let the acid drip down the side of trunk and quarter panel. Acid is, well, acid and you really need to hose it down very well to get that surface clean and stop the acid from just eating away the base metal. The POR-15 stuff works pretty well for some things, but you can't spray it worth a darn, so the epoxy primer is probably your best bet. There are other sprayable paints you can use, but the main thing is get it clean, dry and kill the rust. If you have some small pitting, you can paint a couple coats of POR-15 over the top of that and it will seal it up ok, best if you can paint both sides of the rust pin holes to keep moisture away and give it a hard protective surface. Then you can just scuff up the POR-15 with some sand paper and spray over the top of it just fine when you paint the trunk. OH, and then you can get some seam sealer and just brush it on any of the seals to re-seal them. Best to scrape them clean, rust etch and clean well, then just slop it on like the factory did. It lasted 40 years that way, best to just make a mess and slop it on like they did to make it look right.
Be sure to take the weep hole valves out of the fender wells. They are on the inside edge. You may be able to see them when looking from underneath. I pulled mine out on my Skylark since those pockets got water in them from the leaking back window- and it was full of crud down there, as well. I keep a car cover on it now to protect it from more water intrusion after I cleaned it up. And until I can get the back window fixed.
Thanks guys. I'm not sure if I'll have to coat the whole trunk so epoxy will probably be better since POR15 doesn't work well unless it's treated bare metal. I know it's not recommended but I don't have a spray gun and would have to cover the whole garage to paint in it; are there any decent rattle can epoxy primers on the market as I'm am just looking for a temporary fix? I can't believe how many products are out there and how many different opinions people have on this topic. I've been reading forums and product websites for 2 days now!
Go to an auto paint store and get mar-hyde 3509 one step.Will convert rust to a hard black primer sealer . Will work for what you are requesting. Until you have time/budget for a proper repair.
x2 :TU: This stuff works great! Be sure not to get "silly" with it...it is a PITA to remove once it has cured. Only put it on what you plan to leave it on. I used it to treat the inside edges of my doors, roof, deck lid, etc.. It's great for treating the back sides of welded spots as well.
