At 07:59 PM 5/5/2012, Rocket J Squirrel wrote:
>Oh, THANK YOU DAVID for increasing the number of things that I will
>worry about.

Only too pleased to be of service <removes plumed hat and sweeps low bow>

>The H-shaped "plastic bomb" thing -- I sure hope someone comes up
>with a replacement part so I can just swap it in before mine blows.
>With my luck the thing would decide to blow when I'm in the
>backcountry and out of cell phone range.

I sure hope so as well.  Fortunately the 2.1l haven't got one, though
they have their own plastic nightmares.  My unchecked thought is that
anyone who can sweat-solder ought to be able to run up a onesie given
a sample to work from; but things always seem easier when you haven't
looked at dimensions and such.

>For the expansion tank, uh I'll look for the warning signs. Are new
>tanks available?

Yes.  Pretty cheap, too.

>Say, BTW, I followed your suggestion to pressurize the cooling
>system with a bicycle pump. I didn't know that the nipple on the
>expansion tank's cap was a one-way device.

'Tisn't  It's two zeners in parallel with opposite polarity.  The one
you were pushing on has a breakdown pressure of ?half a pound? and
the one facing the inside of the system has a breakdown pressure of
around thirteen pounds.  That's why and how the coolant gets into the
overflow bottle in the first place, and how it gets sucked back when
the system cools.  So unless your pressure cap is completely out of
spec you were not over pressurising the system.  Totally how it was
meant to work.

Yrs,
d