Technical Dipping Master cylinder to remove internal surface rust

Hi everyone re-building my master cylinder from a 1946 Chevrolet truck its all cast iron the bore is in good condition and I will give it a quick hone. the problem is the inside of the reservoir it has quite a lot of surface rust. Does anybody know of a cheap home dipping chemical I can make up to dip my master cylinder in? Does vinegar work ? Any help appreciated

 

I just rebuilt the MC for my AD truck. It also had surface rust inside, as well as outside. I soaked in Apple Cider vinegar for a week and half and it cleaned it really nice.

 

I think it's white vinegar.
Save the apple cider vinegar for heart burn. Now there's a tech tip for ya.

 

I've done and used it. Vinegar is Vinegar. Are you lacking common sense?

 

You can use a much more aggresive acid than vinegar , the exposure time and temperature of the acid is the key.
Then neutralise in soda ash ( or baking soda).
We do this all the time ,as I rebuild Hydraulic pumps and valves for a living.
We have a 100 gal acid tank.
We never leave cast iron in for more than 30 min and that would be a heavily rusted piece .
muratic acid can be bought at the hardware for $10 to $15 per galon,it may not cut as fast as our industrial chemical but would have to be 10 times faster than vinegar especialy if put in the sun on a warm day.

After the acid dip ,rinse with water then a short dip in baking soda solution, rinse with water again, blow it dry with compressed air then spray it down with WD40 and leave it set for a couple of hours then wash with solvent.
The WD40 keeps it from flash rusting and seems to neutralise any leftover acid in the pores of the cast.
By trial and error , this is how we get the best results.

 

One word - Evaporust. It is probably the only product that I have ever used that did what it said it would. Yesterday I removed an old Ford flywheel from soaking for 2 days. All the rust was gone! Also, unlike vinegar, zero chance of damage to the subject part.

 

Our chemical is Acid Magic by Certol international.
The lable reads ( same as full strength muratic with 90% less fumes)


This was a 2 min soak
We use it for control bodys with spool valves as small as 1/4 inch

 

Vinegar works great, will not damage cast iron and when your finished it can be dumped in the yard or down the sink. If you spill it or get some on you it wont burn you or eat your floor.

Soak it, wire brush it, soak again, rinse, WD40 and reassemble.

 

I've been glass beading mine for 40 years .. may change technique after reading this one.
Thanks !!!

 

Molasses and water.

 

Evaporust will do the job without worry about acid pitting. You can leave the thing in ER for a month and it will not go beyond the rust.

 

I don't think so. I'm just trying to pass along info, like you. I am not saying that apple cider vinegar won't work or that you didn't done do it.
What I am saying is that if you take a look anywhere that shows how to clean with vinegar, white vinegar is specified.
On the other hand, white vinegar is not used for acid stomach.

 

I use white vinegar full strength, molasses will do it but it will take a week or 2 whereas vinegar will do it in less than an hour unless its really screwed up.

 

Also, there are grades of white vinegar on your Wal Mart shelf:

1. White vinegar

2. White CLEANING vinegar (Heinz label)

Apple Cider vinegar is less caustic, aids digestion...(acid stomach)

 

If you're using muriatic, do it outside, not in your shop. The fumes from muriatic acid will cause any open steel to surface rust.

 

This is true, as our 100 gal tank is outside of the building.
For most hobby type situations I would imagine a small tub and a gallon or less of mutatic, which would be easy to do outside.
Temperature makes an incredible difference though.
What will take 5 min at 30deg will take one min at 90

 

All, I know is that it works for me and the proof is in the pudding and talk is cheap. Makes no difference to me what type of vinegar you want to use, but I am happy with Apple Cider.

 

I've used concentrated lemon juice on sheet metal and it worked very well. Shared this with a friend and he used it to clean a '32 door lock assembly....worked real well.

 

Holy vinegar fight! I like the white vinegar from Costco 'cause it's cheap.

 

Depends on mixture concentration. A stronger mixture with molasses will speed up the process. Still will take a few days though. And make sure you don't forget it, cuz it'll be a pile of rust at the bottom of the tank!.

 

Thanks for all the replys will get some white vinegar and see what it does.

 

If you really feel that you must use acid to derust it, think about masking the bore to protect it. Don't hone until you are done getting rid of the rust. No sense taking chances with your brakes, especially with a single master cylinder.