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Login to post Forums » Grassroots Motorsports » Soft (Aluminum) Nut Busting

July 17, 2011 10:16 a.m. flexi New Reader

Get anyone's attention?

Have a 24 mm fitting female fitting screwing over a 22 mm male fitting, both in aluminum. Seems to be slightly corroded. (Part of an empty AC system, under repair)

Is there a way to separate them without destruction?

Multiple shots of penetrating oil - no joy. It is not as if one can put a lot of torque on these aluminum fittings. Got a recommendation for some magic elixir (weasel wizz, or whatever) that is effective on aluminum?

I'm trying to save the outer (female) 24 mm fitting and aluminum line.
July 17, 2011 10:26 a.m. porksboy SuperDork

Use flare nut wrenches, They look like box end but have a smaller cutout in them and contact 5 corners of the nut/ fitting. Snap-on makes ones that contact away from the corner and I have found them to work better. Dont know if anyone else makes them that way. When you loosen the fitting give the wrenches a sharp smack or snatch to break the corrosion loose.
July 17, 2011 10:40 a.m. NOHOME Reader

Weasel juice AND patience is the only way out of this.

If the fitting is priceless, then you need to soak the part and visit with the wrenches over a span of time. It did not get corroded overnight and it won't release overnight either.

I have spent weeks getting some parts to come apart by doing this. Just a few gentle wiggles back and forth until you finally get some movement. Then don't get too impatient and try to remove if still tight.

I have also failed miserably even after all this effort.
July 17, 2011 11:08 a.m. Chas_H New Reader

Try some heat from a propane torch, but not too hot.
July 17, 2011 11:16 a.m. flexi New Reader

In reply to porksboy: Do you use the crow-foot with ratchet or the box-wrench type? It doesn't look like snapon has big enough box wrench style flare wrenches. 21mm is the biggest.

Are the crowfoot ones worth it?
July 17, 2011 11:17 a.m. flexi New Reader

In reply to racinginc215: What kind of toilet bowl cleaner? Whats your favorite brand
July 17, 2011 11:49 a.m. triumph5 Dork

Threads wire brushed clean? Lots of penetrating fluid and patience, as has been pointed out. The bowl cleaner is actually a highly dilluted form of muriatic (or closely related) acid. If it's desperation time, you CAN, and it's tricky, DRIP acid on the threads--were talking using an eye dropper, and hoping the acid will follow the threads, eating the corrosion as it goes. Then rinse throughly with water if it doesn't or does work. I've removed Aluminum duoprops from steel shafts on outdrives doing this as a last resort before cutting the prop off. (Splined shaft, acid's capillary action corrodes aluminum down the splines.) Use gloves and eye protection. Just keep in mind, this is a technique that is one step short of sawzall time.

OTOH, build up a mote of modeling clay around the filling and fill with penetrating fluid, then wait, tap frequently, and wait some more.
July 17, 2011 2:18 p.m. novaderrik Dork

heat with propane torch, spray some penetrating oil on it, tap the outside of the nut with a small hammer. put the best fitting wrenches on the hex heads that you can find with the wrenches arranged so that you can turn the nut loose by squeezing the wrenches together with even pressure. they will probably loosen up- once that happens, you need to "wiggle" it loose and not force it.
July 17, 2011 7:00 p.m. m4ff3w SuperDork

Try some MouseMilk.
July 17, 2011 7:07 p.m. 44Dwarf Dork

two hammers 180 from each other. Bang at the same time not hard just enough to flex the nut and break the bond.
July 17, 2011 7:09 p.m. fasted58 HalfDork

acetone?
July 18, 2011 10:37 a.m. jimbbski Reader

I have started to use plain Dextron ATF for penetrating fluid. Brush it on and let it sit. I have sometimes let it work for day or even weeks, just re-applying the ATF every day or so.

So far it has worked every time.
July 18, 2011 7:45 p.m. kb58 Reader

Heat works VERY well. The first time I tried it, a nut that refuses every assault I could think of came off BY HAND after being heated red-hot. As said though, be careful to not overheat aluminum, there is no cool, red, orange stage. It goes straight from "normal" to "Oh crap."
July 18, 2011 10:28 p.m. Vigo Dork

Nobody believes me until they see it but certain kinds of channel-locks (good ones), used PROPERLY and CAREFULLY, can break anything loose without destroying it, including aluminum fittings large and small. Its a tactile art, though. Not really explainable over the internet.

The two-hammer thing touches on a viable approach (although im not sure the hammers are it). Ive used a similar approach to fix adjusters on a lot of old drum brakes over the years.
July 19, 2011 6:22 a.m. 44Dwarf Dork

I learned the two hamer trick when I worked at a paper mill and the steam lines to the dryers had to be disconected while still hot. 3 inch steel Unions don't like to move when hot when thay were put on cold and torqued.
July 19, 2011 8:22 a.m. ppddppdd Reader

The two hammer trick is a good way to get a stuck ball joint free. Hadn't ever thought to do it on a nut. If you can get in there I bet it'll work.

Or, try putting a wrench on it and whacking it nice and hard down the wrench (ie, toward the fastener, not at a 90 degree angle) while applying as much torque to the wrench as you dare.

I wouldn't heat aluminum in an A/C system much if there's seals anywhere near it.
July 19, 2011 8:38 a.m. Taiden HalfDork

Does anyone make an air hammer that works on the 'hammer trick' principal? Methinks it would be extremely useful for stuck fasteners, especially ones in tight places!
July 19, 2011 9:57 a.m. RossD SuperDork

racinginc215 wrote:

flexi wrote:

In reply to racinginc215: What kind of toilet bowl cleaner? Whats your favorite brand

whatever the wife buys and I steal from one of the bathrooms. I have a bottle of "The Works" I keep in the garage.

The Works has hydrochloric acid in it and the bottle should actually say it on it, too. When you mix it with aluminum it makes hydrogen and will start to disolve the aluminum. Just a little warning; but it should work for getting the corrosion dissolved then wash away with water. (That's also the basics of childhood hooligan device that I will not state the name off, but I already said too much .)

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