this is my first time using this forum, and i was wondering if any of you could tell me how to fix about a 2x2inch square rust hole in my frame.... i just bought the sidekick today actually, and noticed some deep rust on just that area.... i considered sanding it, then boxing it in with metal and maybe putting silicone on it to seal it up from rusting anymore...
also, will the rust return if i dont get it completely off and just weld to the remaining solid parts of the frame even if i silicone it well?
any help would be greatly appreciated

Hi, I'm new here too, in fact I just joined the other day.  Frame rust unfortunately is something I know well.  I had a 1990 Trooper with 160,000 miles on it and ran well.  Unfortunate I put my hand through the frame!!!  It was completely rotted out in the rear, nothing left , in fact, I think the only thing holding up the bumper was force of habit!!!!  It also rotted out near the front wheel, so we traded it in on a 2000 Tracker.  I've been wanting a Vitara/Tracker for a while and we finally came across the right one.  I think in your case your rust prolem is small and very fixable, technically mine was fixable too, just very, very involved, not to mention the entire cargo floor was rusted, and other spots on the body as well, it was just too far gone.  All I can say is whatever you do to patch it make sure there is ABSOLUTELY NO BARE METAL.  Paint everything as completely as posible, including the inside of the frame, and you should be just fine.   BTW you didn't mention where on your frame, that makes a diffrence too, if it's a non load bearing part near no suspension pieces that's great, if it is near something critical just make sure whatever you do is strong.  Hope this helped a little,      Dave

This is probably an east coast problem, I have no rust and it's an 89,
but this is maybe one of the pitfalls of a box style frame, it holds more
junk and water which can work on the metal from the inside out.

One solution might be to get some "creeping oil" it's used in the aviation
industry to inhibit corrosion inside of airplane wings where painting is not
possable, it could be applied thru the rust hole, but far enough inside so it
won't burn off when welding, or drill some small holes, inject the oil then
fill the holes with silicone, this would also allow periodic re-application to
keep the rust away.  I don't know of anyplace exept Spruce Aircraft Specialty
that would have this stuff, I am in no way affiliated with this company, this
is purely meant to be a helpfull idea to my east coast Zuki brothers who
have to put up with this terrible rust problem.

A Zuke is a terrible thing to waste  

It is definetly a East coat thing, we have recently moved from the east out to Vancouver Island on the west coast where I picked up an 89, and the truck with some polish looks like it is new, no rust at all.


Mac

There is a rust treatment/paint that actually works good. It's called Por15. You should be able to go to a local auto body supplier and get them to order it for you. It's a three step procedure that treats existing rust, seals the frame and then a VERY hard paint application. I friend of mine did it on his Jeep resto, and the paint has not been chiped off after 3 years of wheeling. It's alot of work but worth it.
Zig

The proper way to deal with rust is to cut out every single bit, and reweld in new metal.  Rust will come back unless this is done, it is just like cancer.  There are several products i.e. "Miracle Paint" that allow you to paint over existing rust and claim that you will no longer have to worry about it.  Personally I havn't had experiance with these products, I have always been told that the only way to get rid of it is to cut it all out.  It might be worth your while to cut out what you can weld up any and all holes and look for a rolled, or blown engine sidekick then use that frame.  It may end up saving you money in the end as those rust paint products can get pricey.  In fact there is a guy giving away a sidekick here in California.  
Here are some photos of me cutting out rust and welding in patches.  
Hope this helps!

actually i live in port coquitlam (30mins from vancouver) on the west coast... this isnt on the two main frame rails but on the ones that run perpendicular to them to hold up the floor......  the rust is near a mounting point and since im not really interested in unbolting it and raising the body off the frame to do this well, i figured a quick fix of grinding out most of the rust... welding a piece of metal across the hole, then painting/siliconing all remaining surfaces
do u guys think that would work? or would the rust just return later on since there would still be some light rust remaining

Rust will always come back unless you cut it out and replace the steel, but you could get away with what you want for an interm fix, when it gets bad lift up the body a bit and weld a new piece of steel in there. When I lived out east we used to weld new body mounts in all the time as the rust was so bad from the salt on the roads.

Mac