Help...FH Crankshaft got Rusty, what to do?

A friend had this 8BA cranked turned, but it's been sitting in his shop and got a little rusty. He offered it to me, but I am not sure what to think of the rust?





The rust is just on one side, maybe 1/4 to 1/3 of the journals.

Should I try a little Crocus cloth, or?

I don't want to screw it up trying to make it better.

Any ideas would be appreciated.

Thanks,

Neal

 

Use Evapo-Rust, works great, you can get it on ebay or online.
http://www.evaporust.com/

 

I was expecting something really ugly..
But that looks fine, doesnt look like its gone deep or pitted, id just rub it with some fine wetordry paper, say 800 grit and use some WD-40 or similar as a lubricant. There might be some slightly dark marks left where the rust was, but i reckon that cranks fine.

 

When I worked in a machine shop, we polished crankshafts that looked worse than that. If the journals were within spec before the rust, chances are they'll be all right after a polish.

 

Blast it with Pecan hulls?

 

hand polish it with some solvent,(i use gas) and crokis cloth (finegrit) i just bought some to do my 460 crank thats been sittn, it works good

 

Put it in a plastic bag, hose with WD40 and let it sit a while. Then wipe off the rust.
It's already been turned, right?
I have a friend who swears that minor rust pits in a crank journal aren't a big deal, as long as the rust is out and all that's left is the clean pit. "It basically acts like a puddle to hold oil. How can more oil be a bad thing?"
As long as it holds oil pressure, I have to say I can't see any flaw in his logic. We're not talking stuff that is full of pits and rough areas, but what you have there is fine.
And he builds some pretty strong engines that don't blow up.
-Brad

 

Will this technique work if I apply it to my entire car

Danny

 

Thanks for all of the replies.

I tried the WD-40 deal...actually I used Gibbs because that is what I had handy. Sprayed it down and wiped with a rag. That got some of the rust off, the I tried 000 steel wool and Gibbs. That got a little better, the I tried 2000 grit sandpaper and Gibbs. That seemed to get most of the dark spots.

Here is what it looks like now...





I think it will run.

Thanks again,

Neal

 

Neal, that looks good now.
For the finishing touch, maybe take the crank to your local crank grinder,
and have them polish the journals.

 

Looks good....if you still need to get it down just a tiny but. Try some real fine emory cloth.

 

I love the picture!

 

I would for sure scrub the entire crank with hot soapy water (not solvent) and blow out all the oil p***ages, even run some acetone thru the p***ages to get the water out of the crank sludge plugs. Immediately dry it and spray it with WD-40, inside and out. Even crocus cloth will leave abrasive in the metal, and the rust it pulls off is going "somewhere" - - get it all out!

Yeh, great picture! almost wallpaper/screensaver quality!

 

So what do they actually do to "polish" a crank? I don't want to pay for something I could do in my own shop...

Sorry about the clutter in the background, I didn't even notice that when I took the pic...

Neal

 

I've heard from a respectable source just a strip of abrasive wrapped around journal and sawn back&forth by pulling on a leather bootlace wrapped around that! The proper abrasive has leaked out of my head...prolly not 40 grit emery, though.

 

It's 1200 as I recall, and quality stuff, not chinese with random grains of sand. Here's a pic from a Ford manual.

 

Well if you have a lathe its real easy. Just chuck it up and put a center in the other end . Spin it and use some real fine emery cloth I think we used to use 400 grit and polish away. Ive done a lot this way.
Dave

 

Neal, the only difference to what Bruce says above, is crank shops have a motorized "endless belt" polishing gizmo that they draw down on the journals as the crank is being rotated.

1200 grit is about right. BUT for pete's sake CLEAN ALL the oil holes after!

 

put a sanding belt as wide as the journals on a drill around a sanding drum, sand side in or out. rotate the crank against the sanding belt slowly with light pressure on the drill. For the rods, use a spring to suspend a pulley so it makes a blower looking belt setup, so when you rotate the throws, it pulls the spring suspended pulley down with it it and keeps constant tension on it wherever it is in the rotation. It should be set up so the throw at its nearest point just barely bends the belt loop.

 

This is what I did and it worked great. Use 2000 grit wet/dry sand paper, tear a strip as wide as the journal. Spray the journal with WD40, wrap the strip of wet/dry around the journal, wrap a shoestring two times around the sand paper, use the shoestring in a sawing motion to spin the sandpaper and polish the journal. Wash the crank with liquid dish soap and water, spray it well with WD40, then blow it dry with air. Its important to clean it in that sequence.
Aaron

 

Since this post came back from the dead. ^^^^this is what they do, I've seen it.

 

go to walmart and get a rifle cleaning kit and clean the oil p***ages when done polishing it