Yea it is normal...for Toyota's crappy frame paint to not adhear to the welds, and give the rusting process a head start. You will see the same with every new Toyota BOF even on the dealer's lot!
If you look at any Toyota BOF that has gone through a winter or two in the rust belt, you will see the rust is most concentrated around the welds.
Most people on this board aren't bothered by rusty frames, but it is one of my biggest pet peeves! Call me OCD or Crazy or whatever, I just hate getting under my relatively new 4runner, and seeing rust to any degree down there.
Here is my initial thread on this:
http://www.toyota-4runner.org/5th-gen-t4rs/148656-frame-welds-rusting-already.html
And here is how I addressed this issue:
Several months back I went over the frame myself with some Rust Bullet. It took a couple days of work, but I covered every part of the frame, that I could reach, that had surface rust or missing coating with it. I decided to use rust bullet because it is similar to Por-15, and it has been shown to protect as well, if not better, and is more forgiving then Por-15 with proper prep.
Day 1:
-Put the 4runner up on ramps (All 4 tires), removed the spare and skids, and pressure washed the underside.
-I then used a cheap car mitt, and standard car wash soap, and hand washed every part of the frame I could reach/see.
-Rinsed/pressure washed everything under there and dried with with a blower and towels.
-I used 60Grit sand paper scuffed up every area I was going to coat (Basically every frame weld, since they all had surface rust) and any other area with surface rust. (My frame had nothing worse then very light surface rust to begin with, so my prep wasn't too bad)
-I then hand washed and thoroughly rinsed and dried the frame to remove the sanding residue.
-I let it dry overnight, because it has to be 100% dry for the coating to adhere properly. Rust Bullet does have special prep chemicals you can use, but I decided the condition of the frame didn't warrant it.
Day 2:
I applied the "Rust Bullet Automotive" paint to every area that had surface rust or missing frame coating. I used several cheap paint brushes to apply it. I waited 4 hours, then applied a 2nd coat.
4 Hours after the 2nd coat, I applied their "Black Shell" Top Coat over the majority frame.
The "Rust Bullet Automotive" only comes in a Grey Color. While it isn't UV sensitive like Por-15, I didn't want a bunch of grey parts throughout the frame, which is why I top coated it. The Black Shell came out a little more glossier then I would like, but it goes on well with 1 coat, and dries really hard. I feel it will hold up much better again rocks and ect then the factory coat would have.
I left the LCAs and Spare uncoated, even though their welds have surface rust, because they are easily replaceable, and I will be able to see how they hold up vs the rust bullet.
Now that the frame is dirty, the Black Shell has lost its glossiness, and looks like a standard frame coat.
Here is a link to the products:
Rust Bullet Automotive - Products | Rust Bullet
BlackShell - Topcoats - Products | Rust Bullet
*On a side note, before I decided to go with Rust Bullet, I called up their CS line, and the 1st person who answered was very knowledgeable about their product and answered every question I had.
Living in Portland Oregon, where it rarely snows, and they don't use salt, I don't think it would have gotten horribly bad, like what I have seen from people in "The Salt Belt", but there was enough of it exposed where it would have gotten worse over time, and would have bugged the hell out of me, since rust is a huge pet peeve of mine. This is my first new Toyota BOF, and I want to keep it in good condition for as long as possible. At the end of the day, all it took was less then $100 in supplies, and a few days. Now I feel much better when im under the 4runner doing service, looking up at a black frame.
I do feel Toyota does a decent job coating their bodies and Uni-bodys, however they still have a long way to go with their frame coating. It would have been nice for them to put a little more into their coating, so it could be fully covered before the body and components were attached to the frame. You would think with all of the frame rust issues they have had they would, but they need to cut costs somewhere....They don't even bother cleaning up the external casting marks on their engine blocks anymore...
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