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Penetrating oil for aluminum?


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Do any of you 1:1 McAnnical types have a favorite penetrating oil for aluminum on aluminum? I have tried PB Blaster a couple of times with no luck so far. I am trying to get the high side A/C service valve off of the line so I can replace the valve (1994 S-10). This is a pretty clean "local" truck. The neighbor two doors over was the original owner.

The offending item is one of the early R-134a fittings with the rubber seal inside. I have the correct 8-sided socket, but not surprisingly I am starting to round off the fitting. The high side line is NLA from anyone that I can find, and it looks like a bear to get it disconnected from the condensor without dismantling a bunch of things.

 

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Heat! Get a small Butane torch from Harbor Freight and heat the fitting just to the point of melting it. Let it cool a bit, spray more PB Blaster on it and keep trying to remove it, repeat as necessary.

The idea is to get the PB Blaster to be sucked into the threads as the fitting cools plus the expansion and contraction helps break the friction bond..

Edited by Raoul Ross
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There is occasionally seizing of threads, sometimes between dissimilar metals, that will never come apart no matter what you do.

Stainless threads are particularly prone to seizing permanently if the correct anti-seize isn't used during assembly.

Aluminum threads can also seize forever.

NOTE: Flex lines can be field-spliced permanently, and any competent AC shop should be able to make up a complete (hard or soft) or partial line should it become necessary.

Edited by Ace-Garageguy
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  • 2 weeks later...

I already have a butane torch. After a short detour down a dirt road when I discovered that butane isn't available just everywhere in California anymore, I went through four heat/soak cycles and finally extracted the bugger using a boxend on the hex behind it and pliers on the fitting itself.

I installed the new service valve (with the correct 8-side socket) last night and drew a vacuum. I am going to try to charge it tonight if I have time.

Now that I have the old valve out, it looks like some type of steel, not aluminum.

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Edited by Rodent
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