Suggestions for cleaning a crusty Caravel piston? - Page 2

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drgary
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#11: Post by drgary »

That's a surprise. I wonder if the aluminum pistons are original since the stainless on the rest of the machine is high quality. I'm lucky I guess to have one that's stainless and from what I remember of Francesco's photos of successive machines they look like stainless with no corrosion.
Gary
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nk
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#12: Post by nk »

I'm pretty sure the consensus is that they are original. The machine I found mine in had zero signs of customization, maintenance, or ever being opened. Why they switched is anyone's guess. The best I could figure was since it was early on that it was due to Al material properties as a much better conductor and not decreasing production cost since everything else was still Inox. I imagine they switched back when the corrosion issue was discovered.

There's another thread Aluminium Corrosion (Arrarex Caravel and FE-AR La Peppina) where its discussed albeit briefly. The consensus there is to leave it alone or if you must polish it, let the oxide layer form, and lube liberally which is what I did before luckily obtaining a SS piston during OE's closeout. I'm pretty sure OE was treating Aluminium pistoned machines as parts one since I inherited a few Al pistons from them. Based on the big caravel thread it appears that the rate of the Al piston is much smaller than 1/3, and thus unfortunately not big enough to warrant someone from having a piston made in SS.

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drgary
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#13: Post by drgary »

Francesco confirmed that there were some Caravels with aluminum pistons as original equipment. These were mainly in version 1.2. Added: This is typically found with the ones where the shower screen is not held on by a spring.
Gary
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