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MG MGA - cleaning and derusting fasteners

Just a tip for anyone who needs to clean a lot of fastners.

I have a large coffee can's worth of fasteners (and the large oval shaped washers for the wing bolts) for my MGA project that all needed some cleaning up and derusting. I put them all in a plastic bucket and soaked them in bilge cleaner (available from boating stores) which I happened to have some of on hand. It's a strong base, and a great degreaser.

I then rinsed them thoroughly with lots of hot water to remove all traces of the grease, oil and cleaner residue. Then, I soaked them for about 5 minutes in Hydrochloric Acid (Muriatic Acid is availalbe in some plumbing departments, or as a cleaner for mortar...) which instantly removes all the surface rust. Don't put any aluminum parts or chrome parts in the acid that you don't plan on losing or rechroming, respectively, however.

Then rinse well again and spray all with some WD-40 type oil to remove moisture and coat to prevent re-rusting.

I am now running all the fasteners thru a die to chase the threads, but they will all be ready to go when I get (eventually) to the point where they are needed.
AJ Mail

Alan, I don't think the WD-40 will be sufficient to prevent rust forming again. There's some discussion in the archives regarding the re-plating of original fasteners. Its most cost effective when done in batch quantities, but there can be some problems with it. For some parts that were once plated, and now require sand blasting to renew, I've tried coating with a Krylon matte finish spray. A few of these have been on a garage shelf waiting to be installed for a few years with no visible new rust.

George

G Goeppner

Much better than Hydrochloric Acid would be Phosphoric Acid (Ospho), available at many good auto parts or auto paint stores.
Jeff Schultz

Jeff,

Respectfully beg to differ. Phosphoric acid won't remove the rust. It stabilizes it like Naval Jelly. Hydrochloric acid will actually remove the rust, but leaves the surface very prone to further rusting. I'd recommend a phosphoric treatment immediately after the muriatic (hydrochloric) has done its work in removing the rust. (Thoroughly rinse off the Hydrochloric first though.)

By far the best phosphoric acid treatment I've found is Pickex 20. I've had sandblasted parts treated with Picklex 20 remain rust free awaiting primer & paint for over two years hanging in my basement. I get it from autobosystore.com

Regards,
Doug
D Sjostrom

Doug, I agree with Jeff. Phosphoric acid does extremely well at removing rust. A product called Oxi-Solve from the Eastwood Company is a great example. It removes rust AND protects the parts from rerusting.
Jeff Schlemmer

I think I stand corrected despite recent personal experience on heavily rusted fasteners. Perhaps the dilution of the phosphoric acid I used was not optimum for rust removal.
Thanks,
Doug
D Sjostrom

The acid I used is actually a new Muriatic Acid substitute (after 9/11 you need a liscense to purchase the real stuff in the US -- this stuff has been treated somehow to make it safer in case you get it on your skin...dunno how, but it works just like the original on rust) called Acid-Safe or something like that. Got it at a local hardware and paint store.

The bilge cleaner is just a strong degreaser containing lye, I believe -- it does a good job of pruning up your fingers.

I just checked the bucket which is now full of oily fasteners -- not flashing off yet. I may yet treat them somehow.
AJ Mail

As another note, any acid based product will remove rust faster if heated. A small aquarium heater works nicely, and can be had for well under $20. Just beware that there will be more toxic vapors when heated and that a good mask is always recommended.
Jeff Schlemmer

I will add that you should keep any spring steel out of the hydrochloric/muroatic acid treatment. It will eat spring steel like magic leaving nothing but a useless part that will snap like a dry twig. I think the condition is called hydrogen embrittlement.
Beware if it is a valuable or hard to replace part.

Safety Fast!

Jim Haskins

1953 MG TD
J. M. Haskins

Using a halogen-containing acid to de-rust parts is not a good idea. The halogen (chloride in this case) remains on the surface of the iron and will accelerate future rusting in the same way road salt does. The mechanism is catalytic so a small amount of residual chloride is sufficient to eventually destroy the part. The acid will also cause pitting that will occlude the chloride, making it nearly impossible to remove all of it, even with wire brushing.

A better acid would be oxlaic acid. It is readily available as radiator flush and deck brightener. (Look for it on the ingredients part of the label.) The parts solution will have to be warmed and the parts throughly degreased, but this acid will not cause the long-term problems that using hydrochloric will and the ferric oxalate is soluble whereas iron phosphate formed using naval jelly or other phosphoric acid-based product is not very soluble.

The safest way (for the parts) is to electrolytically reduce the rust using a battery or battery charger connected to a bucket of parts on the negative terminal and a piece of stainless steel to the positive terminal. A small amount ( e.g., table spoon/gallon) of either vinegar, baking soda, or KOH (lye) can be added as an electrolyte salt. Bases are slightly more desirable because they don't liberate hydrogen during the electrolysis (safety issue), but both acids and bases will generally work. Google for the procedure.

Steve
Steve Brandt

Phosphoric acid is used to prep body panels prior to priming. Removes oil and flash rust instantly. Most metal prep stuff at the paint shop is phosphoric acid. It removes rust from fasteners quite well in the right concentrations.
Bill Haglan

This thread was discussed between 20/02/2006 and 26/02/2006

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