Have a motor that has some exterior rust. Runs great and all but having a hard time of how I should prep this in a way that will not ruin the seals (rubber, plastic, etc). Thinking about a rust converter that changes the rust to a phosphate but since it etches in to the metal makes me think the acid will hurt the seals. I'm going to use a green wheel on a air power rotary tool to get as much off as I can but that only goes so far with all the nooks..
Distilled white vinegar. Daub it into the stubborn places, then cover the area with Saran Wrap. My rusty crankshaft throws were so bad I wasn't going to bother with it, but it's a Std./std. '38 Ford 221 V8, and I need it... My wife said let her try this, so she put 2 bolts in a flywheel, stood it up, wet (soaked!) a towel with vinegar, then wrapped it all around the length of the crank...then wrapped the whole thing, bottom to top, round and round with Saran Wrap. I left it for 3 days, then unwrapped it...the journals looked black, like smoke black. Wife Joey put it on the 'Big Foot' hand truck, wheeled it onto the lawn, and gave it a quick bath of soap and water...(Soap was Palmolive dish soap, bio degradable, didn't hurt the lawn. Dry it immediately, though...surface rust will follow immediately if you don't. Engine nooks & crannies should be easy...use an old towel and tear off what you need for the spot, then cover and wait. Rather than the green wheel, I'd use some rotary wire wheels...
Don't take it to my machinest who said he wanted to media blast the rust from the hemi he was boring for me. That was 3 weeks ago! I even offered to unbolt it from the boring machine and get it outside for him! The block had flash rust in the lifter galley and up inside the crankcase from being in the hot tank for so long to get the goo off it. All machinests have the lying gene, thye have the ability to look you straight in the eye and tell you the goddamndest things you ever heard.
I'm here to tell you that not all of us are liars, and not only that we can spell too. You are painting a whole group of people with a very wide brush with your bull shit statement. BTW, your mention of "... my machinest(sic)..." suggests that you have been dealing with this individual for some time. Maybe you should look around for a new machinist.
I tried a 50.50 mix of vinegar/water on the inside of a hood came up perfect no picture but it worked great
Thanks guys. Lets say the motor is assembled and been sitting. Now normally we would bag it with some wd-40 on it for added protection or something along those lines. But for whatever reason you didn't.
I know this is a little off of what you're asking, but MOLASSES. I had a 57-64 Olds/Pont third member with limited slip and 4.88 gears. I bought it CHEAP planning to resell it. I lowered the thing into my molasses bath, and left it there for a week. Every couple of days I'd put on the nitril gloves and spin the yoke. Cleaned up real well, and after washing the molasses off, it got lowered into solvent to displace any water, then blow dried and oiled to prevent rust. Friend took it to the swap meet, and we made out pretty good. I recently got a 57, 265 block and crank. The block is covered in grime/oil, and well protected; the crank had the journals rusted. Into the molasses went the crank. Cleaned and redipped a couple of times, washed it off, into the solvent bath, and oiled it up. It's waiting to get turned, but it looks fine. For your assembled engine, I'd plug all the openings, wire brush the heck out of it with a circular wire brush and electric drill, and then do the mild acid wash,. or not. Paint it ASAP. I am Butch/56sedandelivery.
I had a 54 Chevy that I put a low mileage junkyard motor in. Didn't want to spend too much time on it, as customs usually don't look good with the hood up., and it was a used engine. I degreased it, wire brushed the loose rust off (it was REAL rusty!), and sprayed it with POR-15. Next day, second coat of POR, and when it tacked off, painted it. Looked good 10 years later when I sold it.
That Molasses works real good, though I haven't tried a crank or engine block. Item has to be free of grease or oil. Tried a 10% solution on some old tools and they cleaned up. Is a stronger concentration better or quicker?
I've use molasses before and it's just a slow process I couldn't see a benefit in using a higher concentrate. I did find this on the youtube. Haven't done much research on it. Could you link me to the POR product you actually use? When people mention POR I think of the POR-15 as the only product..LOL.
It won't remove it but NAPAs fogging spray is a good to prevent the rust in the first place. I've got a 400 block that I bored and the customer never picked up that was 2 years ago and the bores are still rust free.
Been removing most of the rust with wire brush on a drill or other rotary tool. Also used small air grinder with roloc 12 grit disk. This may quick work of the rust. Hard to reach areas are going to be a pita. I though about sealing the motor up the best I can and taking my sandblaster to it. This is a big motor and do not want to paint it again. What's people thoughts on a self etching primer? Remember the motor is already running. My concern is the acid in the self etching portion will harm the seals?
Yes, POR-15, I use the silver stuff. I usually don't use it on anything that "shows" or is painted nice, but in this case, I took a chance, as I didn't think the engine was that important, or would last too long. Self etch primer is not a miracle worker. It won't remove, or convert rust. It just contains a small amount of acid to bite into the metal for good adhesion, not enough to affect any rust. Won't affect seals or gaskets, either.
You guys who are doing the molasses bath deal should really look into citric acid. You can buy it powdered online cheap, it works really well for rust removal without the stench of molasses or vinegar. Look into it.. sent with tin cans and strings.
I gave a set of EAB heads a molasses bath for about a week. They were very rusty. Came out looking NEW !!!!
Molasses is great if your motor is apart, mine is together. lol I would post pictures of it but I don't want to be crucified
@alphabet soup, yessir I've used citric acid with great results. Bought a bag of powdered citric acid online cheap maybe 25$ for a bag about the size of a medium ziplock. Added about a coffee cup worth to a 5 gallon bucket filled w water and mix well. Soak rusty parts overnight, pull out the parts and give em a quick wire or bristle brush then wash the rust off w clean water. Most parts were good w one soak, if not give it another overnight soak and they'll come out looking like new. I didn't do anything special before painting, just clean well and prep to paint as you usually would. Dump old acid in the grass when it gets to dilluted to use or when your done. It really is that easy, doesnt burn or stink up my garage. It will tingle a bit on cut up hands and fingers but nothing to cry about. Good luck with it ! :edit, I did not use this to prep an already built motor for paint, only loose parts I could soak. Sorry to the OP for the hi jack. Sent from my SAMSUNG-SGH-I317 using The H.A.M.B. mobile app
Im a big fan of oxalic acid "wood bleach" for derusting, molasses is slow, ha ha get it, but works well. For this, Id suggest evaporust, its fast, dab it on the areas you need, dont drench it. Just keep it away from the gaskets. Use baking soda and water mix to neutralize. Actually almost any degeaser, simple green etc and almost any detergent soap is basic on PH scale and will neutralize the acid. Etch primer is fine.
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