Need some recomendations and want to pole the experts. My '78 is all original with 26k original miles. Want to do a little under the hood clean up on a few parts that have developed some surface rust. One part is my master cylinder. Would appreciate information on something to remove the rust without damaging the surface so not to have to paint it right now. Suggestions?
Would eventually like to paint it ( and maybe a few other parts) but don't want to go through all the trouble of taking it off. Since it's not a smooth surface, I think a small brush will accomplish my end result fine. I've had a quick look online and there are so many products it begins to get confusing. The other thing is, with that being the only part being painted black, I don't feel the cost or the quantity available is worth it. If anyone has done something like this on their car and can make some suggestions that would be great.
Thanks in advance for your suggestions. MrM1978

 

Hi MrM,
Not to stir anything up…. but ANY part that you remove the rust from will IMMEDIATELY, (over night, unless you live in the desert), begin to rust again and at a faster rate than it was because you've exposed the metal's surface.
So after you've removed the rust you'll need to put some type of clear barrier finish on the part, or paint it, or plate it.
Regards,
Alan

 

Thanks Alan. Wanted to see if anyone has used any of the rust removers listed on some of the car sites and how they worked. Some have a coating left after removing the rust, zinc I believe. Also looking for a small can of foundry black or a flat black cast iron paint. Don't really need any more than a pint. Finding it hard to find such a small quantity. All suggestions and recomendadtions are welcome and appreciated.

 

Naval jelly does a pretty good job of removing surface rust. Most Home Depots stock it. Apply it w/ a brush, scrub with a fine steel brush and wipe or rinse off.

 

You might try one of those "rust converter" products that are out there. They claim to convert rust into a protective barrier and it's a dull black. They are meant to be a primer for painting afterwards.

 

WD 40 makes a rust converter that will remove the rust and then leave a coating to keep it from rusting again. Home Depot has it.

I have used it and it works fine.

 

Thanks a bunch for the suggestions. Saw a couple of non-toxic home remedies that sounded interesting. One very interesting one was a 1 to 9 part mixture of molasses and water. This guy used a huge cow troft and soaked his car panels for two weeks or so, pressure washed them off and they came out great. Interesting but not exactly what I needed. If you get a chance google it. Seems like a really great way to strip off rust and paint cheap when restoring old car without a lot of sanding and harsh chemicals.
Also found two others. One was lemon juice and borax and the other simply white vinegar.
Had the vinegar, kept soaking down a rag and wiping the master cylinder. Inbetween wipes I used a wire brush to gently brush off the rust. Then used a smaller, softer wire brush to finish. Repeated this 4 or 5 times. Didn't have the WD40 rust converter but had the WD, so I wiped the entire MC down with it. Thought I would try this as I was babysitting and could not leave the house, had these items handy and I have to say it worked well. Other than the engine compartment smelling like a salad, it turned very nice and basically back to original. Used the same process on my brake booster and back of the part the accelorator linkage is connected to. Not sure what the name of the part is but it's metal on the back with a rubber diaphram on the front. Both had a little surface rust and dirt on them and both came out nice and clean.
Will see if the rust comes back. Will then try some of your suggestions. Thanks so much for your input and will let you know if this lasts.

 

I avoid applying WD40 to anything that I might paint later, I could never get the part clean (free of WD40) enough to keep from getting fish eyes in the paint. Hugh

 

Look to Eastwood. They have a graphite based product to apply primarily to cast iron exhaust manifolds. It gives the cast iron a pretty much original cast iron appearance...it covers up rusty iron exhaust manifolds very well and it's not effected by the high temperature of the exhaust maniforlds. It won't matter that your master cylinder doesn't get as hot as an exhaust manifold for it to work. It works out well for any unpainted cast iron surface. Once you put it one, it does a pretty good job keeping rust from not re-appearing....well not re-appearing quickly...if rust re-appears, just slather some more on.

To apply it, stick your finger into the little container, pick up a clump on your finger and then smear it one. To finish, get a paper towel and wipe off any excess.

In the late 1800's or early 1900's, if you had a coal or wood burning iron stove in your kitchen, you'd buy this stuff to keep your stove from developing rust. A well over 100 year old product still useful for today.

 

Remove any loose scale if there is any & use Rustoleum & a small chip brush. You can buy it in a pint & get it from Lowe's. Mine turned out great.

 

Buy a quart of the "Rust Mort", you can apply it with a brush. Let is take affect then rinse, after it dries repaint. I've had great success with that stuff.

 

POR 15 is made to put over lightly rusted surfaces. It's expensive and a PITA to use, but works well.

Or, you can wire brush any loose stuff off, then spray with VHT cast-iron colored paint. If you want to prime it first, use a self-etching primer (over bare metal).

Personally, I would NEVER do any work on a bare-metal part for my car and not clear-coat, paint, or plate it.

 

Thank you everyone for all the great suggestions. Have something to go with on my next project. Really appreciate all the input. MrM