304 Exhaust Manifold Cleaning

So I've been here off and on for a few years now. I'm doing a frame -off on my '72 CJ5 with a 304 and 3 speed, and always trying to save a few bucks here and and there (who's not?). The Jeep had a set of old headers installed when I first bought it (and likely leaking since shortly after they were installed!)....and since I'm a "header-hater"...I scoured the internet for a set of correct stock exhaust manifolds. Finally found a rusty, grime- caked set, but otherwise in decent shape. I wanted to clean them up, so went on youtube to see what was out there besides glass-beading, which the local shop wants $75 to do. I saw a guy that did 50% white vinegar and 50% water and cleaned a set of heads up in a week.... so I gave it a shot. I poured 3 gallons of white vinegar and then added 3 gallons of water into a plastic tub. Here are photos of the manifolds after 4 days sitting in the solution....kind of cool and weird at the same time. I think it may be working to some extent. And no...that's not some design with the light colored bubbles on top of the solution I created...It's some type of chemical reaction. Happy Halloween!!!

 

Hmm. I thought the usual acid for this is oxalic acid, not acetic acid. It used to be the main component in the old two-part radiator flush, but apparently it is harmful to dump it in the drains or sewers. Other possibly less effective compounds took its place. Oxalic acid - Wikipedia You can still buy oxalic acid as "wood bleach."

 

White vinegar is my go-to for removing rust. It takes days but metal comes out rust free. There will be black mung on the manifolds that needs to be removed with a scrunge pad/soap/water or pressure washing. After that you'll start getting flash rust. It takes a long time to wear the vinegar out so plan to use it for a bunch more cleanings.