DIY repair on quarterpanel rust- advice requested

[evident]

I have a 2007 Lexus RX350 with 150K miles with a rusty driver side rear wheel well. i've owned it since 2009 and it's been a champ. However I can't justify getting this repair professionally repaired as the car isn't worth much and I plan to keep it forever anyways.

Imgur: The magic of the Internet


I've tried to research the best way to reasonably do this repair on my own without welding but i've seen so much conflicting information so i just want to make my own post.

1.Should I use the bondo rust repair kit like the following? Bondo® Rust Hole Repair Kit Clamshell, 31591, 6 kits per case | 3M United States

If I used the above kit, Would i sand down to bare metal, and use the body filler on top of bare metal? I thought that bare metal needs to be treated before applying stuff on it? From everything ive seen on youtube it seems like people apply bondo directly onto bare metal. What do I do with the back side of the wheel well? there is some kind of seam that's not a weld that seals the back side metal and the front together.

2. Should I use POR15? I have a POR15 rust repair kit that I've used on a non-body panel (tow hitch assembly) If i went this route, the repair would look less than perfect and be kind of messed up right? Could I use POR 15 on the inner side of the wheel well?

3. Should I sand this down to bare metal, spray self etching primer, then apply an epoxy putty like POR15 Epoxy Putty on it, then sand that and paint? Epoxy Putty - POR-15 (por15.com) I actually did this on my mom's accord before on her wheel well and it seems to be holding up pretty well, as in i haven't seen new rust but it doesnt look the best as I was more or less haphazard. It was also in a spot where there wasn't an inner side of sheet metal.

Any advice would be appreciated on how to tackle this

 

[Fenixgoon]

i think either will work. the generic process is "remove rust, prepare surface, filll, sand, paint, finish" and both those products do that. if you're looking for a smooth and blended finish, the POR15 looks a little more solid than the bondo, so you might have a bit more sanding/blending to do compared to the bondo.

 

[ISAslot]

i've had good success with using epoxy. Just get rid of the rust. if you have a hole use some mesh epoxied from the back side. Then just fill, let dry, and sand down. I then hit it with primer.

 

[mztykal]

Pics of rusty quarter panel?

 

[evident]

Pics of rusty quarter panel?

It's the imgur link in the original post. It's pretty bad. I'll put more up soon.

 

[thedarkwolf]

Naval jelly is a rust disolver/converter whatever. Use that before you bondo over the bare metal.

How much do you care about what it looks like when you are done? If it is just a beater and you are going to drive it into the ground and just want to stop/slow the rust I'd just knock the worst of the rust off and cover it with POR15 and then primer and close enough spay paint.

 

[letmepicyou]

From what I can see in your photo, it looks like the corrosion is in a place where several body panels come together and are spot-welded in place. And, it looks like this corrosion is pretty deep. There are 2 possible way to LEGITIMATELY repair this section. One would be to take a spot weld drill bit and drill out all the spot welds, separate the panels, and replace the panels. This obviously requires lots of work, lots of expense, and lots of time. Welding would also obviously be involved. This is the "return to OEM spec" path.

As a second potential solution, you could grind, cut, and sandblast every bit of rust away, and I do mean EVERY bit, down to bare metal, and you could then "spot-repair" using small pieces of sheet metal cut and hand fit to replace the ground and cut away pieces, weld them into place, and "mig-in" any spots or gaps. This...would be less than ideal, but logically even hand-fit and welded replacement bits of metal will be physically stronger than something that has corroded away completely. Once you have good metal in place you can fill what you need to with body filler (I recommend a duraglass-type filler for anything thicker than 1/8") and etch, prime, and coat the area. It's white, and there are so many whites it can be tough to get an exact match. But there are worse colors, and you said you're not super worried about it so you won't have to blend too far into the rear bumper cover and the rear quarter.

These are your only LEGITIMATE ways of repairing this. There are lots of shady, hap-hazard ways to fix it, of course. But if you want an opinion from a guy that was trained in auto body and has worked in several shops...this is it.

 

[Pacfanweb]

Grind as much rust as you can, treat it with Ospho, which will neutralize the remaining rust, then proceed with the finish work. That's for the "riggedy rig" fix.

To fix it right, cut out all the rust, weld in new metal, do the finish work. And still neutralize inside the panel with Ospho when you have the section cut out.

 

[evident]

From what I can see in your photo, it looks like the corrosion is in a place where several body panels come together and are spot-welded in place. And, it looks like this corrosion is pretty deep. There are 2 possible way to LEGITIMATELY repair this section. One would be to take a spot weld drill bit and drill out all the spot welds, separate the panels, and replace the panels. This obviously requires lots of work, lots of expense, and lots of time. Welding would also obviously be involved. This is the "return to OEM spec" path.

As a second potential solution, you could grind, cut, and sandblast every bit of rust away, and I do mean EVERY bit, down to bare metal, and you could then "spot-repair" using small pieces of sheet metal cut and hand fit to replace the ground and cut away pieces, weld them into place, and "mig-in" any spots or gaps. This...would be less than ideal, but logically even hand-fit and welded replacement bits of metal will be physically stronger than something that has corroded away completely. Once you have good metal in place you can fill what you need to with body filler (I recommend a duraglass-type filler for anything thicker than 1/8") and etch, prime, and coat the area. It's white, and there are so many whites it can be tough to get an exact match. But there are worse colors, and you said you're not super worried about it so you won't have to blend too far into the rear bumper cover and the rear quarter.

These are your only LEGITIMATE ways of repairing this. There are lots of shady, hap-hazard ways to fix it, of course. But if you want an opinion from a guy that was trained in auto body and has worked in several shops...this is it.

I think I might have someone who could do Option 2 for me. At least the welding part. If he can weld new metal in place for me, i can handle the paint part. i already bought the matching paint in aerosol for this vehicle.