Rusty Banged up Exhaust what are my choices?

I have decided to remove the Mac 4-1 Exhaust to get the stock performance back. My exhaust had been sitting in a friends garage for around 4 months. There is some surface rust and pretty deep dents on one of the mufflers from my wreck.

My questions are... Can I spray paint it?

Should I just wrap it?

Do I need to sand it?

If I black wrap it will it rust further under the wrapping destroying it in the long run?

Here is a pic of it.


If anyone wants a mac 4-1 for cheap let me know.

 

it's nasty and stinky but i painted mine with muratic acid and kept them wet with it till the rust was gone, the chrome was dulled enough that paint stuck to it

 

So you soaked it in something like...


http://www.lowes.com/pd_58558-78-GKGM75 ... facetInfo=


Then painted it the color you wanted?

 

acid will work but i always rely on the old sand until smooth method, get rid of most of the rust and use header paint, sandblasting is better but not available to everyone. i like eastwoods header paint but im sure there are others that will do the trick, if you fiberglass wrap them as is it will speed up the decay, its like putting a bandaid on when you need stitches, gotta stop the rust no matter what.

 

that's the stuff.use rubber gloves, glasses and a new cheap brush, outside, on a piece of wood, go slow so you don't splash.
when your done with the last part go back and start over, you want to keep the acid fresh. in 10 or 15 minutes the rust pits should be clean.
rinse them real well and dry them. i warmed them with a heat gun then painted with rustolium bar-b-que black.
that lasted a good year then they needed a touch up with a artist brush where some of the pits didn't get clean

 

What do I rinse them with? Just water?

 

lots and lots of it

 

Like hose? Is it bad to get that stuff or water for that matter.... Inside the exhaust?

 

A machine shop will get them clean for you for a reasonable price (shop around and see what it would cost). If your set on keeping them it would be the best prep possible for paint. Be sure and patch any holes with muffler repair. Use a ceramic based paint.

You can also use Phosphoric acid to remove the rust which won't run the risk of eating the metal like the muriatic. Either way if you do it yourself do follow Polock's advice. The muriatic will burn right away and the fumes can do serious damage to your lungs in about 1/4 of a second. The phosphoric will take longer but it can burn your skin as well.

As long as you fully dry it after your process it will be fine-use a fan or hair dryer-but if you use the muriatic you must make sure you get it all solubilized and rinsed away or it will continue to munch the metal until it is a gas.

 

will Phosphoric acid etch the chrome so paint will stick? muriatic makes it pretty dull but not like battery acid
water won't hurt the insides

 

That sounds scary..... there are no holes in it it's just surface rust and some dents. I cant just sand at it and spray paint it huh?


What about wrapping it? Will the rust continue to eat away under the wrap?

 

Wrapping will ensure continued rusting if you live in a humid climate. You can minimize the rusting if you paint the pipes with a high temp paint. Get a roll of fine emery cloth and sand down all the rusty areas, make sure everything is dry, then paint.

 

What is your budget? I realize you're probably like most of us and the answer is "as cheap as possible.." but you could probably get it ceramic coated for around 2bills...it won't be chrome shiny, but they can do it in a number of colors and they will do all the prep work as well. Here's one place that does it and here is their prices page...

edit;correction...looks like a maxim exhaust might closer to 3bills..

 

Is there any reason that you cant paint the exhaust and then paint the pipe wrap as well to seal it ?

 

Would it make sense while rinsing, to double-check for residual acid with a cup of dilute baking soda and a sponge ?? Then more rinsing??

I sandblasted and used the VHT 1500 paint and it STILL rusted, then (6 months later) I painted over the slightly rusty pipes with BBQ Black RustOleum and they look fine.

 

how about baking soda dissolved in water from a spray bottle or window cleaner with ammonia works too.
you have to etch the chrome somehow and the cleaner the better and seems like the rust will start from any rust you paint over, even a speck.

 

So is the best bet Phosphoric acid, rinsed, wiped down with baking soda water, and rinsed again? Then painted with a "rustoleom" that is a high temp paint?

 

Phosphoric acid will not etch any of the chrome that is in good shape, it will only attack the rusted or bare metal. It will convert any iron oxide to ferric phosphate which is black and non-reactive. Once converted it is easy to remove. Since you are planning on painting you can mix in antifreeze with the phosphoric acid 30/70 and it will also remove any gas, oil, etc. from the pipes. Do this process first and test a small area with either steel wool or 1000grit to see what the chrome under looks like, if its pitted through proceed to..

..etch the chrome you can either sand it or dip it into muriatic acid for a SHORT time. I personally would go the sanding method since it's a small surface area and you can easily reach it all.

No need to 'neutralize' the Phosphoric acid, water rinsing is good enough. If you use the muriatic acid you must neutralize it, and you must begin the finishing process quickly as muriatic acid will open up the metal to the point it will start to flash rust quickly.

I have had really good results with VHT paint for high heat applications, and the Eastwooods, and Por-15 products are all really good-maybe even better than VHT. I suspect the previous problems were simply due to rust still being present when it was painted. Make sure your surface is totally clean and dry before you paint and use really light coats to begin the process.