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Pete Keillor[_2_] Pete Keillor[_2_] is offline
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Default Removing stuck ss screw from aluminum

Hi, everybody. Been out of touch for a few weeks due to rootkit
trojan on computer and no time to mess with it, so turned off wireless
and let it sit. Just re-staged yesterday. Been building a wooden
fence to hide my canoe trailer (bull**** HOA rules).

Anyway, next project is refurbing if possible the trim-tilt unit on my
bay boat. This is a 1999 Yamaha 150 hp 2-stroke. Took it to the
fixit shop near where we keep the boat (about 200 miles to the coast),
their fix is replace the whole dang thing for over 2 boatbucks plus
labor. Figured it was worth a look a that price, plus the trim-tilt
is easy to remove as a subassembly, so I brought it home.

So far, I've got the motor/gear pump off. Corrosion in the threads is
bad, as you'd expect for something on the bracket of a marine
outboard. One cap screw broke off, leaving a decent stub. Others
were stubborn as grim death, but eventually yielded to lots of heating
and PB blaster, alternating over a few days. The broken cap screw has
yet to yield. Continuing the same treatment, a little fire, a little
PB Blaster. This is into a flat machined surface sealed by multiple
o-rings for the different passages. Leak was at this interface.

Worst case, I can buy the new unit and save the labor costs. But it's
worth a lot if I can get the bolt out. I'll probably helicoil the
holes and use a good antiseize if successful. Realistically, if the
boat lasts another 20 years, it'll be somebody else's problem (I'm
61).

Am I missing any good tricks? I remember something about dissolving
steel and leaving the aluminum for broken taps with alum, but will it
work on stainless? Thanks.

Pete Keillor