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What works best to free rusted parts

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What works best to free rusted parts.

Everyone has run into parts with lots of rust that should move but do not move any any more. What worked best for you to get things moving again?

This question has come up several times in the forum. Let us put it into a thread.

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Equal parts acetone and Dextron/Mercon automatic transmission fluid (ATF). Stir thoroughly then apply with a brush or spray bottle and allow to sit.

Works better than any commercial product I've ever tried.

Here's some data to support that:
Tech Tips: Grassroots Motorsports Magazine

"So you deal with a lot of rusty nuts? Go down to the hardware store and buy some acetone, a quart of Dexron Mercon and a refillable spray bottle. In the spray bottle mix the ATF and acetone in a 1:1 mixture.

Spray away and get your nuts loose!

Independent testing of penetrating oils using a single steel bar with 1/2”x20 nuts torqued to 50 ft/lbs and treated with a 10% salt water solution that was allowed to rust. Listed are the chemicals and required removal torque.

-None ………………… 516 pounds

-WD-40 ……………… 238 pounds

-PB Blaster …………. 214 pounds

-Liquid Wrench ….. 127 pounds

-Kano Kroil ………… 106 pounds

-ATF-Acetone mix….53 pounds "

Edited by TMIB
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For small things, I just soak it for a few hours in household vinegar. That vinegar will just flake the rust right off - including scouring out the rust from the pits in the metal as well. Amazing stuff!

For bigger things I've used the WD-40 and Liquid Wrench stuff. A couple applications over a couple days seems to loosen things up.

But the best stuff dad ever got came from an electrician working for the power company. They were replacing a lightning zapped transformer, and he offered dad some of the fluid from inside that junked transformer. Don't know what it was, but that stuff worked great on old farm machinery! Since then I've heard that it contains those PCB's.

So I stick with vinegar and WD-40.


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I found a lot of pieces of bar threaded at the ends and with nuts totally siezed on. They really are totally rusted solid. I keep these in a corner of the shop. When I have finished forging I just lay a couple in the dying fire and leave them. They generally get to a good red. Once they have been heated I simply remove the nut which by that stage san often doesn't even need a wrench. Grease them and put them away for future use. I have done hundreds now and it always works.

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I've had the best results using a 50/50 mix of Brake Fluid and ATF (Automatic Transmission Fluid). For getting bolt/stubs that have broken off in cast iron because of rust; I weld a washer and nut to the bolt/stud, let cool and remove with a wrench. The heating then cooling of the metal will break it loose.

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I find that if you can get a torch on the the troubling nut or bolt and heating to a good red hot then quickly cooling to the touch works good, Sometimes have to repeat this but have never seen it fail. Old equipment with fine threads are big pain to get loose, this heat treatment gets the job done and during the reinstall coat with grease. I also save the old grease cartridges and clean them out keeping the unused grease for this work as well as applying to screws in wood projects. The other suggestion are good ones too and will have other means of breaking stuborn nuts and bolts loose in the future.

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Everything I've used thus far, in no particular order.

-Liquid Wrench (hard to beat)
-PB Blaster (really gets into tight areas)
-CRC 3-36 (Wish I had more of it, great stuff, most all CRC products are great)
-Marvel Mystery Oil (awesome, but takes some time)
-ATF (Great for long soaks to remove even coating of rust)
-vinegar (fast, but will remove more than needed sometimes!)
-used motor oil (slow soak)
-diesel fuel

Edited by keykeeper
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usta use liquid wrench ..but now PB blaster beat that hands down..

tried all the home remedies.. there for the most part useless..:(
from kero to atf, to hot wax, to citric acid.. etc

if the pb doesn't work in a couple days... then heat with torch

by the way...if your going to test ... then allow the rust to occur under natural conditions for 15 years... then apply the treatments.... otherwise i can't see a salt water test to be applicable ( as i've never had anything sit in salt water ).... maybe the results are good for folks that live in coastal areas..;)

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The problem being that some places the natural conditions are pretty lenient---I picked up 100+ feet of 1" dia wrought iron that had been used to hold together a cistern after the 1906 quake here in Socorro NM. It had been in place, outside, 100 years and was held together by threading the ends and using nuts over cross plates.

I removed the 100 years outdoor nuts using my regular adjustable wrench, no oil, heat or witchcraft needed. Back in Ohio I'd probably have to torch them off after 50 years!

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