Jeff

motsco_ wrote:
<...>

> Apples to oranges. The thermometer has a capillary tube that amplifies
> the amount the mercury or spirit is expanding, and it's expanding toward
> the air bubble at the top. That's exactly like the Volvo or Dodge system
> with the pressure cap on top of a reservoir half-full of air.
>
> The Honda coolant expands a bit and builds pressure, but it's the hoses
> that probably absorb most of the expansion, not the reservoir. If you
> were talking about gasoline expanding, that's very different. Water
> doesn't compress, and until it boils it doesn't expand much at all.
> That's why the water pipes in your house hammer when you shut off a tap
> suddenly. For that reason I've installed an air trap in the water line
> to my bathroom shower as a shock absorber. All is now quiet on the
> Western Front.

Water will expand by about 4.3% from freezing to boiling:

http://www.newton.dep.anl.gov/askasc.../chem03335.htm

So if a cooling system contains 8 liters of water (about 2 gallons), it
will expand by about .3 liter, which is about 11 onces, or nearly the
volume in one can of soda.

The coolant will expand by a different amount, because it is not pure water.

Jeff
> :-)
>
> 'Curly'

Grumpy AuContraire

jim beam wrote:
> motsco_ wrote:
>
>> jim beam wrote:
>>
>>>> Volvos and Dodge products that I owned had pressurized reservoirs.
>>>> The coolant level in them went up and down with temperature, but the
>>>> HONDA isn't supposed to, since it's reservoir isn't under pressure
>>>> at all. Boiling hot coolant isn't supposed to take up much more room
>>>> than cold coolant, as long as the rad cap is keeping the pressure up.
>>>
>>>
>>> sorry, that's fundamentally incorrect. coolant liquid most
>>> definitely expands as it heats - for both systems. pressure doesn't
>>> stop coolant expanding, it simply raises the boiling point.
>>>
>>> http://en.wikipedia.org/wiki/Coeffic...rmal_expansion
>>>
>>
>> -----------------------------
>>
>> I should have said "Coolant that is _boiling-hot_ isn't supposed to
>> take up much more room than cold coolant, as long as the rad cap is
>> keeping the pressure up".
>
>
> but that's not true. as the liquid warms up, it expands substantially.
> that's why the "max" mark on the bottle is only half way down, not near
> the top. and that's why old fashioned thermometers work - as the volume
> of liquid in the bulb expands, it rises through the tube.
>
> http://www.forestry-suppliers.com/pr...e.asp?mi=8225#
>
>
>
>
>> The word 'boiling' was used as an adjective, not a verb the first
>> time. If you (disable the cooling fan so as to) boil it, you'll
>> certainly fill the reservoir to the top, but in a healthy Honda
>> cooling system, the level in the reservoir isn't supposed to go up and
>> down 4 - 5 inches every time you drive it.
>>
>> 'Curly'


I think the key here is; "Liquids cannot be compressed."

If a given liquid (at normal ambient temperatures) is heated, it will
expand but remain in a liquid state hence, it has to go somewhere to
accommodate the resultant expansion.

In modern cars, this is the coolant reservoir while in the older tin of
the past, it was simply the space at the top of the radiator.

JT

Grumpy AuContraire

motsco_ wrote:

> jim beam wrote:
>
>> motsco_ wrote:
>>
>>> jim beam wrote:
>>>
>>>>> Volvos and Dodge products that I owned had pressurized reservoirs.
>>>>> The coolant level in them went up and down with temperature, but
>>>>> the HONDA isn't supposed to, since it's reservoir isn't under
>>>>> pressure at all. Boiling hot coolant isn't supposed to take up much
>>>>> more room than cold coolant, as long as the rad cap is keeping the
>>>>> pressure up.
>>>>
>>>>
>>>> sorry, that's fundamentally incorrect. coolant liquid most
>>>> definitely expands as it heats - for both systems. pressure doesn't
>>>> stop coolant expanding, it simply raises the boiling point.
>>>>
>>>> http://en.wikipedia.org/wiki/Coeffic...rmal_expansion
>>>>
>>>
>>> -----------------------------
>>>
>>> I should have said "Coolant that is _boiling-hot_ isn't supposed to
>>> take up much more room than cold coolant, as long as the rad cap is
>>> keeping the pressure up".
>>
>>
>> but that's not true. as the liquid warms up, it expands
>> substantially. that's why the "max" mark on the bottle is only half
>> way down, not near the top. and that's why old fashioned thermometers
>> work - as the volume of liquid in the bulb expands, it rises through
>> the tube.
>>
>> http://www.forestry-suppliers.com/pr...e.asp?mi=8225#
>
>
>
> ----------------------------
>
> Apples to oranges. The thermometer has a capillary tube that amplifies
> the amount the mercury or spirit is expanding, and it's expanding toward
> the air bubble at the top. That's exactly like the Volvo or Dodge system
> with the pressure cap on top of a reservoir half-full of air.
>
> The Honda coolant expands a bit and builds pressure, but it's the hoses
> that probably absorb most of the expansion, not the reservoir. If you
> were talking about gasoline expanding, that's very different. Water
> doesn't compress, and until it boils it doesn't expand much at all.
> That's why the water pipes in your house hammer when you shut off a tap
> suddenly. For that reason I've installed an air trap in the water line
> to my bathroom shower as a shock absorber. All is now quiet on the
> Western Front.
>
> :-)
>

Liquid expansion indeed would be accommodated by hoses until the psi
equals and surpasses that of the radiator cap setting at which point,
coolant will flow into the reservoir.

As I stated earlier, a liquid cannot be compressed (volume-wise) but it
certainly can react to pressure, (boiling point etc.), so accommodation
must be provided for such expansion from temperature increases.

BTW, at around 39°F, water is at it's most compact physical volume.
Temperature increases/decreases will cause it to expand.

JT

jim beam

Grumpy AuContraire wrote:
>
>
> motsco_ wrote:
>
>> jim beam wrote:
>>
>>> motsco_ wrote:
>>>
>>>> jim beam wrote:
>>>>
>>>>>> Volvos and Dodge products that I owned had pressurized reservoirs.
>>>>>> The coolant level in them went up and down with temperature, but
>>>>>> the HONDA isn't supposed to, since it's reservoir isn't under
>>>>>> pressure at all. Boiling hot coolant isn't supposed to take up
>>>>>> much more room than cold coolant, as long as the rad cap is
>>>>>> keeping the pressure up.
>>>>>
>>>>>
>>>>> sorry, that's fundamentally incorrect. coolant liquid most
>>>>> definitely expands as it heats - for both systems. pressure
>>>>> doesn't stop coolant expanding, it simply raises the boiling point.
>>>>>
>>>>> http://en.wikipedia.org/wiki/Coeffic...rmal_expansion
>>>>>
>>>>
>>>> -----------------------------
>>>>
>>>> I should have said "Coolant that is _boiling-hot_ isn't supposed to
>>>> take up much more room than cold coolant, as long as the rad cap is
>>>> keeping the pressure up".
>>>
>>>
>>> but that's not true. as the liquid warms up, it expands
>>> substantially. that's why the "max" mark on the bottle is only half
>>> way down, not near the top. and that's why old fashioned
>>> thermometers work - as the volume of liquid in the bulb expands, it
>>> rises through the tube.
>>>
>>> http://www.forestry-suppliers.com/pr...e.asp?mi=8225#
>>
>>
>>
>>
>> ----------------------------
>>
>> Apples to oranges. The thermometer has a capillary tube that amplifies
>> the amount the mercury or spirit is expanding, and it's expanding
>> toward the air bubble at the top. That's exactly like the Volvo or
>> Dodge system with the pressure cap on top of a reservoir half-full of
>> air.
>>
>> The Honda coolant expands a bit and builds pressure, but it's the
>> hoses that probably absorb most of the expansion, not the reservoir.
>> If you were talking about gasoline expanding, that's very different.
>> Water doesn't compress, and until it boils it doesn't expand much at
>> all. That's why the water pipes in your house hammer when you shut off
>> a tap suddenly. For that reason I've installed an air trap in the
>> water line to my bathroom shower as a shock absorber. All is now quiet
>> on the Western Front.
>>
>> :-)
>>
>
> Liquid expansion indeed would be accommodated by hoses until the psi
> equals and surpasses that of the radiator cap setting at which point,
> coolant will flow into the reservoir.

no, they're fiber reinforced so this /doesn't/ happen. or at least, not
to a significant extent at 13psi. otoh, you can argue that the metal
tubes in the radiator expand if you really want to get fixated on this
stuff.


>
> As I stated earlier, a liquid cannot be compressed (volume-wise) but it
> certainly can react to pressure, (boiling point etc.), so accommodation
> must be provided for such expansion from temperature increases.

but what we're discussing here simple thermal expansion, not boiling.
"expansion" when boiling is due to phase change - a whole different ball
of wax.


>
> BTW, at around 39°F, water is at it's most compact physical volume.
> Temperature increases/decreases will cause it to expand.

water is one of the few substances out there with weird anomalies in its
thermal expansion coefficient.

jim beam

motsco_ wrote:
> jim beam wrote:
>> motsco_ wrote:
>>> jim beam wrote:
>>>>> Volvos and Dodge products that I owned had pressurized reservoirs.
>>>>> The coolant level in them went up and down with temperature, but
>>>>> the HONDA isn't supposed to, since it's reservoir isn't under
>>>>> pressure at all. Boiling hot coolant isn't supposed to take up much
>>>>> more room than cold coolant, as long as the rad cap is keeping the
>>>>> pressure up.
>>>>
>>>> sorry, that's fundamentally incorrect. coolant liquid most
>>>> definitely expands as it heats - for both systems. pressure doesn't
>>>> stop coolant expanding, it simply raises the boiling point.
>>>>
>>>> http://en.wikipedia.org/wiki/Coeffic...rmal_expansion
>>>>
>>>
>>> -----------------------------
>>>
>>> I should have said "Coolant that is _boiling-hot_ isn't supposed to
>>> take up much more room than cold coolant, as long as the rad cap is
>>> keeping the pressure up".
>>
>> but that's not true. as the liquid warms up, it expands
>> substantially. that's why the "max" mark on the bottle is only half
>> way down, not near the top. and that's why old fashioned thermometers
>> work - as the volume of liquid in the bulb expands, it rises through
>> the tube.
>>
>> http://www.forestry-suppliers.com/pr...e.asp?mi=8225#
>
>
> ----------------------------
>
> Apples to oranges.

apples to apples - it's exactly the same principle.


> The thermometer has a capillary tube that amplifies
> the amount the mercury or spirit is expanding,

and how many liters of fluid are in the bulb? it's /exactly/ the same
principle having a 3 liter coolant system and a 500cc expansion bottle.



> and it's expanding toward
> the air bubble at the top.

it's not an air bubble.


> That's exactly like the Volvo or Dodge system
> with the pressure cap on top of a reservoir half-full of air.

it really doesn't matter whether the expansion bottle is pressurized or
not - the expansion is the same because the volume of the liquid is not
affected by pressure.



>
> The Honda coolant expands a bit and builds pressure, but it's the hoses
> that probably absorb most of the expansion, not the reservoir.

untrue - the fiber reinforcing of the hoses is there to specifically
prevent that. it would be impossible to maintain the 13psi pressure to
prevent boiling if the hoses could simply expand.



> If you
> were talking about gasoline expanding, that's very different. Water
> doesn't compress, and until it boils it doesn't expand much at all.

dude, did you read the wiki cite? thermal expansion coefficient of
water is /huge/ compared to something like steel.


> That's why the water pipes in your house hammer when you shut off a tap
> suddenly. For that reason I've installed an air trap in the water line
> to my bathroom shower as a shock absorber. All is now quiet on the
> Western Front.

indeed, but it's got nothing to do with thermal expansion.

mjc13

E Meyer wrote:
>
>
> On 2/20/08 2:30 PM, in article j50vj.11208$wG2.3708@trndny09,
> "mjc13<REMOVETHIS>" <"mjc13<REMOVETHIS>"@verizon.net> wrote:
>
>
>>E Meyer wrote:
>>
>>>
>>>On 2/20/08 6:20 AM, in article gWUuj.16648$FK2.1405@trndny08,
>>>"mjc13<REMOVETHIS>" <"mjc13<REMOVETHIS>"@verizon.net> wrote:
>>>
>>>
>>>
>>>>Tegger wrote:
>>>>
>>>>
>>>>>"mjc13<REMOVETHIS>" <"mjc13<REMOVETHIS>"@verizon.net> wrote in
>>>>>news:_8Iuj.4853$0%3.3542@trnddc06:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>mjc13<REMOVETHIS> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Tony Hwang wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>mjc13<REMOVETHIS> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> When I had the oil changed in November, I was told they had to
>>>>>>>>> add
>>>>>>>>>"quite a bit" of coolant to the reservoir. Since the car came from
>>>>>>>>>NM, with a spotty service record, I had hoped that it was simply
>>>>>>>>>not topped off ever. Now, three months later, with only moderate
>>>>>>>>>driving, I see the reservoir is virtually empty again. I don't see
>>>>>>>>>excessive white smoke in the exhaust, or smell antifreeze in it -
>>>>>>>>>although I haven't sniffed it specifically for that, yet. The oil
>>>>>>>>>looks fine. I don't smell coolant inside the car, either. It would
>>>>>>>>>be hard to spot a slow drip in this wet Winter weather. How common
>>>>>>>>>are internal head gasket leaks in this engine, as opposed to slow
>>>>>>>>>leaks in the reservoirs?
>>>>>>>>
>>>>>>>>
>>>>>>>>Hi,
>>>>>>>>First I'd replace the rad. cap and see.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Good idea. I didn't realize that pressure leaks were such a common
>>>>>>>problem. I may have the system pressure-tested if replacing the cap
>>>>>>>doesn't work. Thanks.
>>>>>>
>>>>>>
>>>>>> I took the car to a local shop today. They do free pressure tests
>>>>>> (I
>>>>>>gave them $20 anyway). No leaks, including the cap. Unless I'm missing
>>>>>>something, it has to be the #@!@# head gasket, right? Assuming it's
>>>>>>going straight to the exhaust and not burning much, how safe is it to
>>>>>>leave it alone? Any suggestions?
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>The pressure test needs to be performed in two places.
>>>>>1) the cooling system, and
>>>>>2) the combusion chambers.
>>>>>
>>>>>the first is done in conjuction with the introduction of UV dye to the
>>>>>coolant, this being detected on the outside with a black light. The
>>>>>second consists of shop air being blown into each combustion chamber,
>>>>>then the rad filler neck being then inspected for bubbles.
>>>>>
>>>>>There is a third test that uses special paper test strips dipped into
>>>>>the rad filler neck. These change color in the presence of combustion
>>>>>gases in the coolant.
>>>>
>>>> The procedure in the Honda manual online in the UK is to just use a
>>>>hand pump-operated pressurizer with guage, and see if the pressure drops
>>>>in the cooling system or cap. I don't know which they used at the shop...
>>>>
>>>>
>>>>
>>>>>Your problem is NOT the rad cap. If it were, the reservoir would be
>>>>>FULL.
>>>>
>>>> Good point.
>>>>
>>>>
>>>>
>>>>
>>>>>There is also the possibility of a worn water pump. In that case the
>>>>>coolant would drip down the block under the timing belt cover and may
>>>>>not be obvious. Findinig that leak means carefully inspecting the crank
>>>>>pulley area.
>>>>>
>>>>>Do not put this off. You WILL damage your engine, possibly badly. You're
>>>>>supposed to check your coolant level every time you open the hood, or at
>>>>>least once a week.
>>>>>
>>>>>
>>>>
>>>> What I'm going to do, assuming I can even afford the cost of a new
>>>>gasket done by the dealer, is to tell them to look for leaks, especially
>>>>at the water pump. If they find none, I'll have them replace the head
>>>>gasket. Shouldn't they install the new timing belt and water pump for no
>>>>extra labor charge (they will be providing the parts, not me) when they
>>>>do the gasket? I'm also having the front oil seals replaced as a
>>>>preventive measure. Thanks for your response. If you could answer this
>>>>post before this evening, when I drop it off, I'd appreciate it greatly.
>>>
>>>
>>>Seems like you're jumping the gun a little bit here. How low was it in the
>>>reservoir? When you say reservoir do you just mean the overflow tank, or
>>>the radiator?
>>>
>>>In normal use, the system will settle out to where the overflow tank sits at
>>>the "min" mark when the engine has cooled & the level will rise to around
>>>the "max" mark when the engine is hot & has been running for a while.
>>>
>>>I certainly would not spend money replacing a head gasket that has not even
>>>been diagnosed. There is not enough info here to even say for sure that
>>>there is a problem.
>>>
>>
>> I know. On the one hand it may be nothing. On the other it could be
>>engine-threatening. The dealer told us in essesnce, that we can't afford
>>a new gasket - didn't even quote a price. And we wonder why cars aren't
>>maintained like they used to be...
>>
>> The reservoir was empty, or virtually so, both times.
>
>
> What did the dealer say he thought the problem was?
>
> If the reservoir is empty, but the radiator is full (I'm still not clear if
> that's what you are saying), have you checked that the reservoir itself, or
> the hose to it is not damaged and is actually letting the coolant leak out?
>

It turned out to be a leaking water pump. I believe the Grand Prize
goes to Tegger (or maybe Ray) for guessing that. I'm relieved. The pump
also had one frozen bolt, so I'm wondering if the pump really *was*
replaced 5.5 years ago and 50k miles ago, like th printout from the West
coast dealer said. It shouldn't have been in such bad shape - the
replacement interval is 6 years and soemthing like 80k miles...

Grumpy AuContraire

jim beam wrote:
> Grumpy AuContraire wrote:
>
>>
>>
>> motsco_ wrote:
>>
>>> jim beam wrote:
>>>
>>>> motsco_ wrote:
>>>>
>>>>> jim beam wrote:
>>>>>
>>>>>>> Volvos and Dodge products that I owned had pressurized
>>>>>>> reservoirs. The coolant level in them went up and down with
>>>>>>> temperature, but the HONDA isn't supposed to, since it's
>>>>>>> reservoir isn't under pressure at all. Boiling hot coolant isn't
>>>>>>> supposed to take up much more room than cold coolant, as long as
>>>>>>> the rad cap is keeping the pressure up.
>>>>>>
>>>>>>
>>>>>>
>>>>>> sorry, that's fundamentally incorrect. coolant liquid most
>>>>>> definitely expands as it heats - for both systems. pressure
>>>>>> doesn't stop coolant expanding, it simply raises the boiling point.
>>>>>>
>>>>>> http://en.wikipedia.org/wiki/Coeffic...rmal_expansion
>>>>>>
>>>>>
>>>>> -----------------------------
>>>>>
>>>>> I should have said "Coolant that is _boiling-hot_ isn't supposed to
>>>>> take up much more room than cold coolant, as long as the rad cap is
>>>>> keeping the pressure up".
>>>>
>>>>
>>>>
>>>> but that's not true. as the liquid warms up, it expands
>>>> substantially. that's why the "max" mark on the bottle is only half
>>>> way down, not near the top. and that's why old fashioned
>>>> thermometers work - as the volume of liquid in the bulb expands, it
>>>> rises through the tube.
>>>>
>>>> http://www.forestry-suppliers.com/pr...e.asp?mi=8225#
>>>
>>>
>>>
>>>
>>>
>>>
>>> ----------------------------
>>>
>>> Apples to oranges. The thermometer has a capillary tube that
>>> amplifies the amount the mercury or spirit is expanding, and it's
>>> expanding toward the air bubble at the top. That's exactly like the
>>> Volvo or Dodge system with the pressure cap on top of a reservoir
>>> half-full of air.
>>>
>>> The Honda coolant expands a bit and builds pressure, but it's the
>>> hoses that probably absorb most of the expansion, not the reservoir.
>>> If you were talking about gasoline expanding, that's very different.
>>> Water doesn't compress, and until it boils it doesn't expand much at
>>> all. That's why the water pipes in your house hammer when you shut
>>> off a tap suddenly. For that reason I've installed an air trap in the
>>> water line to my bathroom shower as a shock absorber. All is now
>>> quiet on the Western Front.
>>>
>>> :-)
>>>
>>
>> Liquid expansion indeed would be accommodated by hoses until the psi
>> equals and surpasses that of the radiator cap setting at which point,
>> coolant will flow into the reservoir.
>
>
> no, they're fiber reinforced so this /doesn't/ happen. or at least, not
> to a significant extent at 13psi. otoh, you can argue that the metal
> tubes in the radiator expand if you really want to get fixated on this
> stuff.
>

Er, the entire structure expands as temperature rises... Engine,
radiator etc.


>>
>> As I stated earlier, a liquid cannot be compressed (volume-wise) but
>> it certainly can react to pressure, (boiling point etc.), so
>> accommodation must be provided for such expansion from temperature
>> increases.
>
>
> but what we're discussing here simple thermal expansion, not boiling.
> "expansion" when boiling is due to phase change - a whole different ball
> of wax.
>

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.


>
>>
>> BTW, at around 39°F, water is at it's most compact physical volume.
>> Temperature increases/decreases will cause it to expand.
>
>
> water is one of the few substances out there with weird anomalies in its
> thermal expansion coefficient.

Tegger

motsco_ <motsco_@interbaun.com> wrote in
news:13rpah1bmfjdo50@corp.supernews.com:


>
> Volvos and Dodge products that I owned had pressurized reservoirs. The
> coolant level in them went up and down with temperature, but the HONDA
> isn't supposed to, since it's reservoir isn't under pressure at all.
> Boiling hot coolant isn't supposed to take up much more room than cold
> coolant, [...]



But it does. ALL materials expand with heat.

The reservoir level naturally rises and falls as the coolant heats and
cools. This is the purpose of the various seals in the rad cap, and for the
very presence of the (unpressurized) reservoir in the first place.

You don't have to take my word for it. Check your own reservoir's level at
dead-cold. Drive the car to full-hot, then have another look at the level.
It will be at least a half-inch higher.

Coolant is constantly traveling in and out of the reservoir with every
heat-cool cycle. It's a normal and necessary feature of a modern sealed
cooling system's operation.




--
Tegger

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

z

On Feb 21, 11:49 am, motsco_ <mots...@interbaun.com> wrote:
> The Honda coolant expands a bit and builds pressure, but it's the hoses
> that probably absorb most of the expansion, not the reservoir. If you
> were talking about gasoline expanding, that's very different. Water
> doesn't compress, and until it boils it doesn't expand much at all.

?? the average honda owner, meaning me, can see a rise of maybe an
inch or so in the reservoir after the engine is hot.

z

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.
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.

z

On Feb 21, 8:36 pm, Tegger <teg...@tegger.c0m> wrote:
> motsco_ <mots...@interbaun.com> wrote innews:13rpah1bmfjdo50@corp.supernews.com:
>
>
>
> > Volvos and Dodge products that I owned had pressurized reservoirs. The
> > coolant level in them went up and down with temperature, but the HONDA
> > isn't supposed to, since it's reservoir isn't under pressure at all.
> > Boiling hot coolant isn't supposed to take up much more room than cold
> > coolant, [...]
>
> But it does. ALL materials expand with heat.
>
> The reservoir level naturally rises and falls as the coolant heats and
> cools. This is the purpose of the various seals in the rad cap, and for the
> very presence of the (unpressurized) reservoir in the first place.
>
> You don't have to take my word for it. Check your own reservoir's level at
> dead-cold. Drive the car to full-hot, then have another look at the level.
> It will be at least a half-inch higher.
>
> Coolant is constantly traveling in and out of the reservoir with every
> heat-cool cycle. It's a normal and necessary feature of a modern sealed
> cooling system's operation.
>
> --
> Tegger
>
> The Unofficial Honda/Acura FAQwww.tegger.com/hondafaq/

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.

Jeff

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

motsco_

z wrote:
> On Feb 21, 11:49 am, motsco_ <mots...@interbaun.com> wrote:
>> The Honda coolant expands a bit and builds pressure, but it's the hoses
>> that probably absorb most of the expansion, not the reservoir. If you
>> were talking about gasoline expanding, that's very different. Water
>> doesn't compress, and until it boils it doesn't expand much at all.
>
> ?? the average honda owner, meaning me, can see a rise of maybe an
> inch or so in the reservoir after the engine is hot.

=======================

Yep. That's exactly what I said in the first place:

> I've owned six Hondas and the level in the reservoir never changes more than about 1", hot or cold, summer or winter.

'Curly'

jim beam

z wrote:
> On Feb 21, 11:49�am, motsco_ <mots...@interbaun.com> wrote:
>> The Honda coolant expands a bit and builds pressure, but it's the hoses
>> that probably absorb most of the expansion, not the reservoir. If you
>> were talking about gasoline expanding, that's very different. Water
>> doesn't compress, and until it boils it doesn't expand much at all.
>
> ?? the average honda owner, meaning me, can see a rise of maybe an
> inch or so in the reservoir after the engine is hot.

try driving up grapevine [california i5], in summer, at 95. i guarantee
you'll see more than that. unless there's something wrong, it won't
overheat, but fluid level will be right at the top of the bottle.

jim beam

z wrote:
> On Feb 21, 8:36�pm, Tegger <teg...@tegger.c0m> wrote:
>> motsco_ <mots...@interbaun.com> wrote innews:13rpah1bmfjdo50@corp.supernews.com:
>>
>>
>>
>>> Volvos and Dodge products that I owned had pressurized reservoirs. The
>>> coolant level in them went up and down with temperature, but the HONDA
>>> isn't supposed to, since it's reservoir isn't under pressure at all.
>>> Boiling hot coolant isn't supposed to take up much more room than cold
>>> coolant, [...]
>> But it does. ALL materials expand with heat.
>>
>> The reservoir level naturally rises and falls as the coolant heats and
>> cools. This is the purpose of the various seals in the rad cap, and for the
>> very presence of the (unpressurized) reservoir in the first place.
>>
>> You don't have to take my word for it. Check your own reservoir's level at
>> dead-cold. Drive the car to full-hot, then have another look at the level.
>> It will be at least a half-inch higher.
>>
>> Coolant is constantly traveling in and out of the reservoir with every
>> heat-cool cycle. It's a normal and necessary feature of a modern sealed
>> cooling system's operation.
>>
>> --
>> Tegger
>>
>> The Unofficial Honda/Acura FAQwww.tegger.com/hondafaq/
>
> 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.

almost zero. there are two springs - one for high pressure exit, the
other is practically zero return. unscrew the radiator cap when cold
and see how much vacuum there is when you release.