Tegger

z <gzuckier@snail-mail.net> wrote in
news:eb120ecd-16d6-44df-9bf3-3c7fc9243265@41g2000hsc.googlegroups.com:


>>
>>
>
> my idle question is, how much negative pressure is required to suck
> the coolant in. obviously, the spring keeps the in valve shut at zero
> pressure, but when the coolant cools off, there's negative pressure in
> the block which sucks the coolant from the reservoir. we assume the
> pressure of the spring on the valve leading from the block to the
> reservoir is what it's labeled as, but i just wonder how much residual
> vacuum remains in the block when the spring shuts the input valve. for
> no reason other than idle curiosity.



There are no springs on the inlet valve.

If you study the bottom of the rad cap, you'll discover either:
1) a round, thin rubber flap smaller than a dime, or
2) a wiggly post with a plastic disc on the end of it.

These are the inlet valves. It takes /next to/ zero negative pressure for
the rubber flap type to allow coolant back into the rad, and /definitely/
zero for the wiggly post type, which is always open until pressure shuts
it.

This assumes, of course, that both types are CLEAN. Goop and crud will plug
up the inlet and prevent free flow of coolant back to the rad.

This futher assumes you're using the correct OEM ND caps. If you've got
aftermarket crap, all bets are off as to how they work.

--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

z

On Feb 25, 6:35 pm, Jeff <kidsdoc2...@hotmail.com> wrote:
> z wrote:
> > On Feb 21, 7:44 pm, Grumpy AuContraire <Gru...@ExtraGrumpyville.com>
> > wrote:
> >> Um, I said "boiling point" as a yardstick that is subject to change
> >> depending on how much pressure the liquid is subject to at the time.
>
> > of course, the coolant at operating temp is quite a bit above the
> > "boiling point" of 212 degrees, that's why it's pressurized.
>
> Actually, the thermostat on most cars is below 212 F. And the boiling
> point is above 212 with the antifreeze.
>
> > in other words, you've gone from about 500 fahrenheit degrees above
> > absolute zero, to about 700 degrees. as a first approximation, that's
> > gonna see a 40% expansion. i hope your hoses don't expand that much.
>
> It's actually going to be about 4% from O to 80 c (about 180 F).
>
> http://www.simetric.co.uk/si_water.htm
>
> Coolant will expand by a different amount, because it has antifreeze and
> other additives in it.
>
> Solids don't increase by 40% in volume from -40 F to 212 F. Why would
> you think water would?
>
> Jeff

wow. i stand corrected. my "estimate" obviously didn't include the
zero temp term,
i.e. if volume = A +B(absolutetemp) I was estimating that A = 0, which
obviously it doesn't.