Getting alum. out of oil-line threads. How to?

[cstreit]

I need some ideas here...

Pulled the oil lines off a customers thermostat and being 30 years old, all the alum threads from the thermostat came along with it.

So now I have alum. embedded in the threads of $800 worth of oil lines.

How do i get it out? I tried picking it a bit with no luck at all. I was thinking a dremel with a cutoff wheel to "weaken" it and then more picking, but would love some clever ideas in case that doesn't work.

Chris

[jpnovak]

First, plug the lines with paper towels so the bits don't get down in there. (but you knew that ) Silicone plugs work better.

Try to heat with a propane torch. The Al should expand at a faster rate than the steel nut. It should be easy to pick out after that.

btw, I have used those thread savers for thermostats. I think you will find that the outer 5 threads or so have pulled. The savers will screw on all the way to the base of the thermostat.

[AZ1977911]

You might try using a thread file on first full thread and then chasing with a die. Thread files and appropriated chasing dies can be found at a local machinery supply house.

Greg

[cstreit]

36mm tap and die though? eep I don't even want to know how much they run! (found an M24, cost $250!)
Thanks guys... Any more clever ideas?!

[ossiblue]

You might try jpnovak's idea of thread savers--use one as a chase.Sounds like you might need them anyway on the thermostat.

[Chuck Moreland]

There must be some type of acid that eats aluminum, but is kinder to steel and brass.

Who is a chemist?

[911pcars]

Here's one chemical solution (a pun):

Once upon a time, I sent my front hood latches to be replated with yellow zinc. The pieces came back except for the threaded pin. The owner denied loosing it. Only later did I realize the pin was made of aluminum or pot metal which sorta disappears in whatever acid solution they use in the plating process. Explore the process and you'll discover the acid that works.

Sherwood

[cgarr]

We use a cleaning product in our stainless steel roasters (sodium hydroxide) that cautions you to keep alum out of the product because it will destroy it, Printers also use something to etch their alum printing plates, so there is stuff out there, just need someone who knows? There are also products to make/etch circuit boards, I dont know if it will work on alum like copper?

[Early_S_Man]

No smoking during this proceedure!!!

Goggles and protective gloves, MANDATORY!

I don't want to hear about some Pelican that had to make a trip to the ER to be treated for aluminum shards and muriatic acid splashed into the EYES!!!

After the steel fittings have been degreased and plugged ... diluted Muriatic Acid will loosen or totally eat away the aluminum shards. I suggest diluting the acid until it only has bubbles of hydrogen apppear, not the really aggressive frothing ... you can test the acidity level on a scrap of aluminum foil.

Apply the muriatic acid [HCl] to the threads with a dropper or brush, being careful not to get it on the outside of the fitting -- it will remove any plating. When bubbling has stopped, allow liquid to run out quickly or sponge up with paper towel. Try the dental pick again to see if the shard has loosened. If not, apply more acid and wait five minutes. If shards are loose, rinse fitting with water, and proceed to remove remainder of shards.

Good luck!

[cstreit]

Thanks for the suggestions guys. All really great ideas...

I ended up using the oxy-acet torch and blasted the alum scraps with a quick hit. They nearly slagged and I was able to use a pick to get them out as they started to curl/harden. Chased up the threads with a file and they are good as new.

Thanks again for all the great ideas!