Under-carriage Rust in my 03accord
 

Hi,
I recently bought a 03 accord from somebody who was previously in VT. Now I found that it has got lot of Under-carriage Rust. I don't know how to remove /stop it from spreading. I checked the local honda dealer and they don't do any kind of rust treatment. I even checked with couple of body-shops and none of them do rust treatment.
Any suggestions are greatly appreciated.

Look in your phone book for places that sell supplies to auto-body shops. Like paint. You'll want to look for products like rust-converter and rust prevention stuff. Some of that stuff sprays on from an aerosol can. Sometimes that stuff is gooey like grease. It will be important that you do NOT obstruct any drain holes on the underside of the car.

There are many rust treatment sprays. I am not sure which is good. Moreover I am scared to do it myself. So looking out for some shop.

Search "bobistheoilguy.com" for "rust prevention". There was a long thread on undercoatings to prevent rust. My take was that the oil/waxy coatings worked best but had to be renewed every 2-3 yrs. One "roll-your-own" spray was mixture of toilet bowl wax seal and kerosene sprayed on underbody. Canandians raved about some underbody spray (another oily/waxy spray) that was commericially available but I've forgot the name.

good luck

You will be hard-pressed to find someone that will treat a vehicle already with a rusting problem. What's to keep you from coming back a year later and claiming their treatment didn't work and want compensation? Not saying you would just a thought. Most people as you have seen are out of the business. Remember "Rusty Jones??"

There are all kind of rust treatments out there. The stuff that auto parts store sells did not work for me - I'm in MI.
What seems to work is POR 15, a specialized paint that seals the rust in. Had treated my VW underbody and went thru a few MI winters, still looks good.
Critical is surface prep, wire brush the rust off best you can, degrease surface with mineral spirit before wire brushing, and after. Then use Metal Prep, a diluted phosphoric acid solution that eats some of the rust off and leaves a coat of phosphate on the surface. Then cover with POR, wear respirator, 1-2 coats.
You'll find POR and Metal Prep at auto painter's supply stores, or online. If the surface will be exposed to light, need to cover with a final coat of paint, since POR reacts to UV rays. If you do that, spray some primer over POR when still tacky, then final coat after it's dry.
Then you can undercoat on top of that.

POR15 is good stuff, but application is messy. It sticks to everything, including you and is very, very difficult to remove. I did not find any solvents that would remove after dry. It has to wear off, a 3-4 day process. It is very difficult to perform adequate surface prep on rusted underbody.

good luck

Is there special paint for the undercarriage? I noticed two small rust spots on mine when I was changing oil and wonder if I can just sand it and put some paint on it?

If it's only underneath Rust Oleum would be fine. Need to be sure you pay close attention to cleaning and sanding all existing rust.

RustOleum & others make some kind of rust converter product to use first (turn rust into black magnetite). Then paint or whatever to match the rest of the underside.