radiator caps, cooling system pressure

[Ashton Crusher]

I was thinking of putting a higher pressure cap on one of my cars to
increase the factor of safety against boiling. Looking thru the web
for info on the likelihood of changing from 7 psi to 13 psi causing
leaks I found little on that issue but did find a couple references to
the pressures created by the water pump. One site boasts of a 19 PSI,
$25 cap to get you thru your "hard driving".
http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar.html
Thought I'd see if anyone else has heard of this. The claim was that
the water pump could create over 30 PSI of pressure. Since that is
double the normal operating pressure of most modern cars I find it
hard to believe. If the system was at full 15 psi of pressure while
the car is idling and then your floored it and ran it up to near
redline and created another 30psi of additional pump pressure, or
even 10 psi of additional pressure downstream at the radiator cap, you
would immediately cause the system to have to vent to the overflow to
relieve this higher pressure. I've never seen a car vent due to me
revving the engine up while I'm working on it. Thoughts?????

[Tony Hwang]

Ashton Crusher wrote:
> I was thinking of putting a higher pressure cap on one of my cars to
> increase the factor of safety against boiling. Looking thru the web
> for info on the likelihood of changing from 7 psi to 13 psi causing
> leaks I found little on that issue but did find a couple references to
> the pressures created by the water pump. One site boasts of a 19 PSI,
> $25 cap to get you thru your "hard driving".
> http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar.html
> Thought I'd see if anyone else has heard of this. The claim was that
> the water pump could create over 30 PSI of pressure. Since that is
> double the normal operating pressure of most modern cars I find it
> hard to believe. If the system was at full 15 psi of pressure while
> the car is idling and then your floored it and ran it up to near
> redline and created another 30psi of additional pump pressure, or

> even 10 psi of additioingnal pressure downstream at the radiator cap, you

> would immediately cause the system to have to vent to the overflow to
> relieve this higher pressure. I've never seen a car vent due to me
> revving the engine up while I'm working on it. Thoughts?????
>

Hi.
There is a over flow bottle for coolant/anti-freeze. Ever
cleaned/flushed your rad. and maintain proper level of
coolant/anti-freeze in your rad.? If the car is old, messing with cap
can spring
a leak.

[hrho...@sbcglobal.net]

On Apr 21, 6:11 pm, Tony Hwang <drago...@shaw.ca> wrote:
> Ashton Crusher wrote:
> > I was thinking of putting a higher pressure cap on one of my cars to
> > increase the factor of safety against boiling.  Looking thru the web
> > for info on the likelihood of changing from 7 psi to 13 psi causing
> > leaks I found little on that issue but did find a couple references to
> > the pressures created by the water pump.  One site boasts of a 19 PSI,
> > $25 cap to get you thru your "hard driving".

> >http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar....

> > Thought I'd see if anyone else has heard of this.  The claim was that
> > the water pump could create over 30 PSI of pressure.  Since that is
> > double the normal operating pressure of most modern cars I find it
> > hard to believe.  If the system was at full 15 psi of pressure while
> > the car is idling and then your floored it and ran it up to near
> > redline   and created another 30psi of additional pump pressure, or
> > even 10 psi of additioingnal pressure downstream at the radiator cap, you
> > would immediately cause the system to have to vent to the overflow to
> > relieve this higher pressure.   I've never seen a car vent due to me
> > revving the engine up while I'm working on it. Thoughts?????
>
> Hi.
> There is a over flow bottle for coolant/anti-freeze. Ever
> cleaned/flushed your rad. and maintain proper level of
> coolant/anti-freeze in your rad.? If the car is old, messing with cap
> can spring

> a leak.- Hide quoted text -
>
> - Show quoted text -

AMEN!

[bob haller]

On Apr 21, 9:50 pm, "hrhofm...@sbcglobal.net"

DONT EVEN THINK ABOUT THIS WITH A CHEVY VENTURE! their engine the 6
cyc one tends to develop super expensive head gasket leaks as is......

some things are best left alone

[Ed Pawlowski]

On Sun, 21 Apr 2013 15:21:32 -0700, Ashton Crusher <de...@moore.net>
wrote:

>I was thinking of putting a higher pressure cap on one of my cars to
>increase the factor of safety against boiling.

How often does that happen? If it is frequent, you have other
problems that need to be fixed. Last time I had a boil over was
probably in the 1960's or so.

This is not the proper thing to do. The engineers have put a lot of
work into getting the right temperature and pressures and you think
you can do a better job? Really?

[cl...@snyder.on.ca]

A water pump cannot produce system pressure because it just moves
water from one side of the pump to the other. Expansion due to heat is
what builds pressure..

[cl...@snyder.on.ca]

On Sun, 21 Apr 2013 19:08:23 -0700 (PDT), bob haller <hal...@aol.com>
wrote:

I'd never overpressure anything with a plastic tank rad. Actually I
wouldn't overpressure ANY system.

[harry]

On Apr 21, 11:21 pm, Ashton Crusher <d...@moore.net> wrote:
> I was thinking of putting a higher pressure cap on one of my cars to
> increase the factor of safety against boiling.  Looking thru the web
> for info on the likelihood of changing from 7 psi to 13 psi causing
> leaks I found little on that issue but did find a couple references to
> the pressures created by the water pump.  One site boasts of a 19 PSI,

> $25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar....

> Thought I'd see if anyone else has heard of this.  The claim was that
> the water pump could create over 30 PSI of pressure.  Since that is
> double the normal operating pressure of most modern cars I find it
> hard to believe.  If the system was at full 15 psi of pressure while
> the car is idling and then your floored it and ran it up to near
> redline   and created another 30psi of additional pump pressure, or
> even 10 psi of additional pressure downstream at the radiator cap, you
> would immediately cause the system to have to vent to the overflow to
> relieve this higher pressure.   I've never seen a car vent due to me
> revving the engine up while I'm working on it. Thoughts?????

The only way to increase the system pressure would be to change the
thermostat to a higher temperature one so increasing temperature as
well as pressure.
You would then have to change the radiator cap too. But changing the
radiator cap alone wouldn't change the pressure but in the event of
engine overheat/pressure would negate the protection it gives.

Very unwise, you may get hoses bursting and engine overheating .
If your engine is overheating there is a problem with the radiator
(blocked) or the thermostat not fully opening.
Possibly slack belt (drives the water pump).
Electric fan (or it's thermostat) if it has one faulty.
Waterways in cylinder block/head blocked/corroded.

[tra...@optonline.net]

On Apr 21, 11:15 pm, cl...@snyder.on.ca wrote:
> On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "hrhofm...@sbcglobal.net"

> what builds pressure..- Hide quoted text -

>
> - Show quoted text -

You might want to rethink that one. Water isn't going to
move through a system without pressure to push it. I wouldn't
expect the pressure to be very high, but there has to be pressure
due to the pump.

As for the question at hand, what is unstated is if there is
actually a problem, ie is the car overheating? If it is, then
finding out the cause of that instead of trying to raise the
boiling point of the coolant via pressure would seem to be
the better approach. For example, if he has a bad thermostat
or collapsing hose, he'd be just covering up the real problem.

[tra...@optonline.net]

On Apr 22, 2:31 am, harry <harry130...@btinternet.com> wrote:
> On Apr 21, 11:21 pm, Ashton Crusher <d...@moore.net> wrote:
>
>
>
>
>
> > I was thinking of putting a higher pressure cap on one of my cars to
> > increase the factor of safety against boiling.  Looking thru the web
> > for info on the likelihood of changing from 7 psi to 13 psi causing
> > leaks I found little on that issue but did find a couple references to
> > the pressures created by the water pump.  One site boasts of a 19 PSI,
> > $25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar....
> > Thought I'd see if anyone else has heard of this.  The claim was that
> > the water pump could create over 30 PSI of pressure.  Since that is
> > double the normal operating pressure of most modern cars I find it
> > hard to believe.  If the system was at full 15 psi of pressure while
> > the car is idling and then your floored it and ran it up to near
> > redline   and created another 30psi of additional pump pressure, or
> > even 10 psi of additional pressure downstream at the radiator cap, you
> > would immediately cause the system to have to vent to the overflow to
> > relieve this higher pressure.   I've never seen a car vent due to me
> > revving the engine up while I'm working on it. Thoughts?????
>
> The only way to increase the system pressure would be to change the
> thermostat to a higher temperature one so increasing temperature as
> well as pressure.

Dumb as ever. The current cap releases pressure at 7 PSI when
the car overheats. He's proposing changing it to 13 PSI so that
when it is overheating, it will not release until that higher pressure
is reached. That results in a higher pressure when overheating
exactly as he claimed and doesn't require changing the thermostat.

> You would then have to change the radiator cap too. But changing the
> radiator cap alone wouldn't change the pressure but in the event of
> engine overheat/pressure would negate the protection it gives.
>

Dumb as ever. When the engine overheats, which is what he's
specifically concerned about, having that higher pressure cap will
result in higher pressure.

> Very unwise, you may get hoses bursting and engine overheating .
> If your engine is overheating there is a problem with the radiator
> (blocked) or the thermostat not fully opening.
> Possibly slack belt (drives the water pump).
> Electric fan (or it's thermostat) if it has one faulty.

> Waterways in cylinder block/head blocked/corroded.- Hide quoted text -

>
> - Show quoted text -

That part is correct. Even a stopped clock is occasionally correct.

[MLD]

"Ashton Crusher" <de...@moore.net> wrote in message
news:pco8n814o0f0cp36f...@4ax.com...

Lots of comments--my two cents: First of all, the water pump is a
centrifugal pump and as such the pressure rise across the pump is a function
of it's speed. The flow output of the pump is a function of the system
characteristics-- Pressure drop vs Flow So changing pressure caps and
thermostats will not change the operating behavior of the pump. The purpose
of the pressure cap is to raise the boiling point of the fluid. This allows
you to run the coolant at higher temperatures (greater than 212F) without
causing it to boil. Just because you have a 180 deg thermostat doesn't mean
that the coolant at running at 180 deg-----because of the cap, typically,
the coolant boiling point is closer to 234 deg F (or higher). That's why
they say never to remove the cap until the coolant cools down--if you remove
the cap too soon, the system pressure becomes 15 psia (atmospheric). the
boiling point becomes 212F and you get a great big flash of steam as the
coolant immediately changes from a liquid to a vapor. As the coolant
temperature increases, it's density (Specific Gravity) decreases and because
it's weight remains constant, the only other variable is it's volume which
increases. Because the cooling system volume is fixed the coolant pressure
will increase (no room to expand) from atmospheric to whatever the cap is
set for and then it is vented to the over-flow bottle.
The downside of increasing the pressure cap setting over what's specified is
two fold---At the higher cap setting, all the system components will be
subjected to pressures beyond design intent--not a good idea. The same
applies to the operating temperature. In summer like days the coolant
temperature will go beyond normal design intent. In both cases, you're
moving in a direction to accelerate component failures.
MLD

[harry]

Thoughts?????

One other possibility is you may have a blown head gasket.

[tra...@optonline.net]

On Apr 22, 11:57 am, harry <harry130...@btinternet.com> wrote:
> Thoughts?????
>
> One other possibility is you may have a blown head gasket.

The other very real possibility is that harry is the village idiot,
as has been proven time and time again.

[cl...@snyder.on.ca]

On Sun, 21 Apr 2013 23:31:02 -0700 (PDT), harry
<harry...@btinternet.com> wrote:

>On Apr 21, 11:21�pm, Ashton Crusher <d...@moore.net> wrote:
>> I was thinking of putting a higher pressure cap on one of my cars to
>> increase the factor of safety against boiling. �Looking thru the web
>> for info on the likelihood of changing from 7 psi to 13 psi causing
>> leaks I found little on that issue but did find a couple references to
>> the pressures created by the water pump. �One site boasts of a 19 PSI,
>> $25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar....
>> Thought I'd see if anyone else has heard of this. �The claim was that
>> the water pump could create over 30 PSI of pressure. �Since that is
>> double the normal operating pressure of most modern cars I find it
>> hard to believe. �If the system was at full 15 psi of pressure while
>> the car is idling and then your floored it and ran it up to near
>> redline � and created another 30psi of additional pump pressure, or
>> even 10 psi of additional pressure downstream at the radiator cap, you
>> would immediately cause the system to have to vent to the overflow to
>> relieve this higher pressure. � I've never seen a car vent due to me
>> revving the engine up while I'm working on it. Thoughts?????
>
>The only way to increase the system pressure would be to change the
>thermostat to a higher temperature one so increasing temperature as
>well as pressure.

Harry, you are incorrect on this. The cap alone WILL cause most
suystems to run at a higher pressure as long as the vehicle runs at a
minimum of 160F. The thermostat only controls the MINIMUM operating
temperature of an engine, so even an engine with a 160 thermostat can
run at 195F, or higher. The cap allows the pressure to build to a
MAXIMUM of the rated pressure - at which point it releases into the
overflow to regulate the pressure.

>You would then have to change the radiator cap too. But changing the
>radiator cap alone wouldn't change the pressure but in the event of
>engine overheat/pressure would negate the protection it gives.
>
>Very unwise, you may get hoses bursting and engine overheating .
>If your engine is overheating there is a problem with the radiator
>(blocked) or the thermostat not fully opening.
>Possibly slack belt (drives the water pump).
>Electric fan (or it's thermostat) if it has one faulty.
>Waterways in cylinder block/head blocked/corroded.

Or bad timing, or bad mixture, or simply overloading the engine. But
yes, you got ONE thing right - installing a cap with a pressure higher
than the system is designed for CAN cause problems with hoses,
radiators, heater cores, etc..

[cl...@snyder.on.ca]

Which WILL cause the pressure to increase rapidly if it is causing an
overheating problem - and even a 30psi cap would vent under these
conditions

[Ashton Crusher]

No, the car is not overheating. It's never overheated. What happened
is that I installed an AC unit in this 60 Dodge. That has made it run
about 10 degrees hotter then it used to, mainly from just having the
condenser there in front of the radiator. So I was thinking about
whether it would be a good idea to go to a 13 pound cap instead of the
7 pound one on it. Just to give a bigger margin of safety when the
temps here get up to 110. The manual for the car lists the 7 pound
cap for non-ac cars and the 13 pound cap for AC cars. Just curious if
anyone has ever seen this increase in pressure cause an immediate leak
to happen. The Radiator was rebuilt 10 years/10,000 miles ago. The
heater core is factory original. Now, on a 95 degree day it's running
up to 205 on the freeway and 195 around town. Thermostat is 180.

[Ashton Crusher]

It would just change it to the pressure for AC cars. For it's first
52 years of use it was without AC. I added AC to it.

[Ashton Crusher]

On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
<harry...@btinternet.com> wrote:

I didn't want to make the original post into a novel but it appears a
lot is being read into what wasn't included. That car is not having
any problems at all right now. I'm just looking at increasing the
factor of safety against overheating because I just added AC to it.
Non-ac cars use a 7 pound cap and AC uses 13. But it's a 52 year old
car (well maintained) and the downside would be if adding 6 pounds
more pressure is likely to create any leaks, like in the 52 year old
heater core. Nothing leaks now. I'm just torn between being
proactive and getting a higher pressure cap "just in case", or just
sitting tight and seeing how the temperatures run as the weather heats
up.

[David L. Martel]

Ashton,

> No, the car is not overheating. It's never overheated. What happened
> is that I installed an AC unit in this 60 Dodge. That has made it run
> about 10 degrees hotter then it used to, mainly from just having the
> condenser there in front of the radiator. So I was thinking about
> whether it would be a good idea to go to a 13 pound cap instead of the
> 7 pound one on it.

I don't follow this. Your radiator is running about 10 deg. F (?) hotter
with the AC, so what? Why is that a problem? You aren't anywhere near the
boiling point of your coolant, are you? Assuming you have a 50:50 mixture
and 7 psi your boiling point is about 255 deg. Changing to a 13 psi cap
would improve things by raising the boiling point to about 270 deg.
Unless you are getting close to 250 I don't understand why you want to do
this. Be sure to check my math. These figures are quick guesstimates.
Sorry, sounds like a waste of money. Keep an eye on the temp gauge this
Summer though till you're sure.

Dave M.

[Ashton Crusher]

So far it's not a problem. I've just never run anything with such a
low pressure cap before. Some of my newer cars will run upwards of
235 on really hot days so I'm wondering if this one does will the 250
be enough of a cushion.

[MLD]

"David L. Martel" <mart...@frontier.com> wrote in message
news:kl4hj8$paj$1...@dont-email.me...

There is noting wrong with your logic. The coolant is already being ported
into the overflow tank with the OEM pressure cap. Putting in a cap that
cracks at a higher pressure probably won't even change anything with respect
to when the coolant starts to go into the overflow tank. In a closed system
(completely full and cap shut) the coolant pressure increases rapidly as the
fluid starts expanding (without the cap opening the pressure could easily
get up to a 1000 psi). Going from 7 to 15 psi would have a relatively
insignificant change in the way things work. It doesn't change the
operating temperature, just raises the boiling point of the coolant. And
operating at a higher pressure than OEM is moving in a trouble direction.
BTW, one can calculate pressure vs temperature in a closed system--just look
up "Bulk Modulus" and fluid compressibility.
MLD

[Ed Pawlowski]

On Mon, 22 Apr 2013 11:44:02 -0700, Ashton Crusher <de...@moore.net>
wrote:



>

>It would just change it to the pressure for AC cars. For it's first
>52 years of use it was without AC. I added AC to it.

If that is factory spec, it should be OK. OTOH, since it is over 50
years old, I'd not want to increase pressure if I did not have to.

[cl...@snyder.on.ca]

13 psi on a '60 mopar pretty well guarantees you will have some
expensive cooling system repairs in your future. If you are worried,
which you should not be, put on an electric fan in front of the
rad/condensor.

[The Daring Dufas]

My 1965 Dodge Dart used a 13psi radiator cap on the good old Slant Six
radiator, at least that's what the part look up states. o_O

TDD

[cl...@snyder.on.ca]

Actually, the spec is14psi on the 60, but I often put a lower
pressure cap on an older car to protect the rad. If the rad is solid,
and the heater core is solid, and the hoses are good, you should be ok
with the 14 lb cap. But that's a big if.

If the temperature is well under 210F with the air on, you don't need
the heavy cap - and that's not nearly as big an if, generally
speaking.

[Tony Hwang]

Hi,
As well today's cars are monitored and controlled by computers. Better
not fool around.

[harry]

On Apr 22, 6:07 pm, "trad...@optonline.net" <trad...@optonline.net>
wrote:

Exhaust gases from a slight head gasket leak will boil the water and
over pressure the system.
You don't really know much do you?

[cl...@snyder.on.ca]

Actually the gasses from the leak pressurize the system, blowing the
water out - which causes overheating. Harry doesn't know much either.

Been proven many times.

[Nate Nagel]

Do the A/C cars come with a different radiator than non-A/C cars?

given the info you give I would think that this should be OK assuming
everything is in tip-top shape. However you may end up replacing the
heater core if there's a weak spot in it, likewise with any old hoses.

You may also want to consider retrofitting a coolant recovery bottle
like modern cars, that way you won't have to constantly keep an eye on
the radiator's water level, and due to not having any air in the system,
should theoretically make it slightly more resistant to corrosion
(although I'd still change the coolant every two years anyway just for
insurance.) You'd need the proper radiator cap for that, so the
radiator can suck coolant back in through the overflow tube when it
cools down.

good luck

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

[Nate Nagel]

On 04/22/2013 02:31 AM, harry wrote:
> On Apr 21, 11:21 pm, Ashton Crusher <d...@moore.net> wrote:
>> I was thinking of putting a higher pressure cap on one of my cars to
>> increase the factor of safety against boiling. Looking thru the web
>> for info on the likelihood of changing from 7 psi to 13 psi causing
>> leaks I found little on that issue but did find a couple references to
>> the pressures created by the water pump. One site boasts of a 19 PSI,
>> $25 cap to get you thru your "hard driving".http://www.mishimoto.com/mishimoto-high-pressure-radiator-cap-13-bar....
>> Thought I'd see if anyone else has heard of this. The claim was that
>> the water pump could create over 30 PSI of pressure. Since that is
>> double the normal operating pressure of most modern cars I find it
>> hard to believe. If the system was at full 15 psi of pressure while
>> the car is idling and then your floored it and ran it up to near
>> redline and created another 30psi of additional pump pressure, or
>> even 10 psi of additional pressure downstream at the radiator cap, you
>> would immediately cause the system to have to vent to the overflow to
>> relieve this higher pressure. I've never seen a car vent due to me
>> revving the engine up while I'm working on it. Thoughts?????
>
> The only way to increase the system pressure would be to change the
> thermostat to a higher temperature one so increasing temperature as
> well as pressure.
> You would then have to change the radiator cap too. But changing the
> radiator cap alone wouldn't change the pressure but in the event of
> engine overheat/pressure would negate the protection it gives.

What? you haven't any clue how a cooling system works do you? Please
just shut up if you don't have any knowledge of what the fuck you're
talking about.

[Nate Nagel]

Like I said in a previous post, a coolant recovery bottle would be my
first step... I never did like seeing that air gap at the top of the
radiator, and it's not good for anything to have it there.

[micky]

On Mon, 22 Apr 2013 11:42:25 -0700, Ashton Crusher <de...@moore.net>
wrote:

That should mean the thermostat is wide open. But the thermostat
could be broken. You can replace it, or hang this one into a pot of
water whose temp is climing. Use a candy thermometer or something
that goes up to 190 to see if the thermostat opens all the way at 180.

I've only done this once, and I don't remember how sure I was that it
was open, or not open, all the way. That is, I didn't know where all
the way was, in practical terms.

Maybe you need a trailer package. Well, just the bigger radiator.

Plus what Dave L said.

Heater cores in many many cars are a pain to replace. Lots of things
on top of them, including parts of your recently added AC, which iiuc
doesn't use rubber hoses, uses metal hoses. Am I right about that?

[micky]

On Mon, 22 Apr 2013 11:50:28 -0700, Ashton Crusher <de...@moore.net>
wrote:

>On Mon, 22 Apr 2013 08:57:20 -0700 (PDT), harry
><harry...@btinternet.com> wrote:
>
>>Thoughts?????
>>
>>One other possibility is you may have a blown head gasket.
>
>I didn't want to make the original post into a novel but it appears a

Making a big mistake. I've already shopped it to a publicsher, and
he's discussed it with a NY producer. Since you hadn't even though
of it, I'll take 17 percent. Contact me at Telex;723345.

>lot is being read into what wasn't included. That car is not having
>any problems at all right now. I'm just looking at increasing the
>factor of safety against overheating because I just added AC to it.

Your conflating over-pressure with over-heating. Containing the
pressure won't make it cooler.

[bob haller]

On Apr 25, 4:45 pm, micky <NONONOmis...@bigfoot.com> wrote:
> On Mon, 22 Apr 2013 11:50:28 -0700, Ashton Crusher <d...@moore.net>

adding a transmission oil cooler is probaly a good idea:) with a
transmission oil filter in series it might save a expensive
transmission rebuid someday:)

[Ashton Crusher]

On Thu, 25 Apr 2013 16:38:42 -0400, micky <NONONO...@bigfoot.com>

I've checked it (with infrared thermo gun) quite a few times even
before putting the AC on it and it seems that the car, in cool
weather, runs up to 180 and stays there as it should with a 180
thermo. In hotter weather it would go up to around 190-195 on the
freeway. Now with the AC it's added about 10 degrees but still has a
lower plateau at 180.

>I've only done this once, and I don't remember how sure I was that it
>was open, or not open, all the way. That is, I didn't know where all
>the way was, in practical terms.
>

I've checked several and a few were bad and would only open about 1/8
inch. Good ones open maybe half an inch.

>Maybe you need a trailer package. Well, just the bigger radiator.
>
>Plus what Dave L said.
>
>Heater cores in many many cars are a pain to replace. Lots of things
>on top of them, including parts of your recently added AC, which iiuc
>doesn't use rubber hoses, uses metal hoses. Am I right about that?

Since this is an added ac it won't interfere much with the original
heater. Here in AZ it's not unusual for bad heater cores to just be
bypassed :-)

[Ashton Crusher]

On Tue, 23 Apr 2013 18:26:08 -0400, Nate Nagel <njn...@roosters.net>
wrote:

Prior owner put one on it and it seems to be working correctly.

[micky]

On Thu, 25 Apr 2013 18:02:36 -0700, Ashton Crusher <de...@moore.net>
wrote:

>

>>Heater cores in many many cars are a pain to replace. Lots of things
>>on top of them, including parts of your recently added AC, which iiuc
>>doesn't use rubber hoses, uses metal hoses. Am I right about that?
>
>
>Since this is an added ac it won't interfere much with the original
>heater. Here in AZ it's not unusual for bad heater cores to just be
>bypassed :-)

I did that once. I had a leak, a hose spraying iirc, just as we
arrived outside some Federal building, not a museum, just south of the
Mall in DC. My friend's girfriend worked there and we were picking
her up at the end of the day. She took me down to the engineer's room
and he gave me a piece of pipe 2 or 3" long. Now I probably
couldn't get into the building even if I needed blood.

[MLD]

<cl...@snyder.on.ca> wrote in message
news:qna9n89tjrmrielh8...@4ax.com...

I guess you need to know how a centrifugal pump works. Pressure rise
across the pump is function of the square of its speed. Double the pump
speed and the delta P across the pump increases 4X. Expansion due to heat
will increase system pressure if it is in a closed system. If a fluid can
expand without being constrained---no significant change in pressure.
MLD

[Tony Hwang]

Hi,
It would also matter how hot the water already is.
How old is the car? Is the rad fan. electric?
Thermo. clutch driven with belt?
Or real old car with straight belt driven? No water temp.
gauge on the dash?(very good idea to have one)

[Guv Bob]

"MLD" <M...@verizon.net> wrote in message news:ljs061$dvo$1...@dont-email.me...

Well, I give each of you half credit. LOL! At a certain RPM, the pump head (outlet-inlet pressure) and flow rate are both are fairly indept of the coolant temperature as long as the coolant stays a liquid (normal condition) when going through the pump. The engine heat raises the coolant temperature and the pressure (remember this from skool... PV=nRT), but (and this is a big butt) as long as the pump turns at the same RPM, the head should stay about the same.

FWIW, here's a decent drawing of a water pump cross-section
http://assets.hemmings.com/story_image/83720-500-0.jpg

[MLD]

"Guv Bob" <guvbo...@yahooooooooooooooo.com> wrote in message
news:3ZSdnfm4kvzLKfzO...@earthlink.com...

A couple of comments--PV=nRT is an equation used in gas flow calculations
not when the fluid is a liquid. Don't understand where you are coming from.
Just for the record, at constant speed the pressure rise across a
centrifugal pump does not remain constant. Typically, there is a droop
(loss of delta P) as the pump flow demand increases. Relatively
insignificant at first but if the flow demand gets large enough, then the
Pump Delta P can drop significantly. Flow demand is dictated by the
characteristics of the the system in question--that is, how the delta P vs
Flow of the system (line losses etc.) matches up with the delta P vs flow of
the pump. Where the two intersect will be the operating point of the
System. The idea is to match them so that the intersection takes place
where the droop in pump deta P is relatively insensitive to flow demand.
MLD

[mike]

Riddle me this.
In a CLOSED system FILLED with INCOMPRESSIBLE liquid, the pressure is
whatever
the pressure is.
The pump can't put more pressure on the output side than is on the input
side because it's a CLOSED system FILLED with INCOMPRESSIBLE liquid.

Do pump principles applied to OPEN systems really apply?

[MLD]

"mike" <ham...@netzero.net> wrote in message
news:lju945$87n$1...@dont-email.me...

Don't understand either of your comments. Could you expand your
explanations so they make some sense?
Do you know what happens if you dead end a centrifugal pump (Zero flow)
while its running?? The discharge pressure might not change but you better
be prepared to see the fluid temperature skyrocket.
You seem to to make a big point out of INCOMPRESSIBLE fluid. Got some news
for you, Ready---fluids, aka liquids, are not INCOMPRESSIBLE!!! Have you
ever heard of "Bulk Modulus", entrained air or compressible flow as they
apply to liquids?
Do you know what would happen to the pressure in a closed system if the
fluid temperature (say water) was increased but the fluid was not able to
expand due to the closed (or fixed) system volume?
Hint: Delta P=(BM) x (Delta V)/V
Clue: Pressure can increase up to the thousands! Want to try and conduct
your own experiment? Close the water inlet shut off valve in your house.
Keep all faucets closed and of course, lock the hot water tank relief valve
so that it doesn't open. Now just crank up the temperature of your water
heater. This ought to seek out your system's weak link.
MLD

[Ashton Crusher]

Great Question. My original question remains unanswered .... Does the
water pump ADD another 10 to 30 psi internal pressure (as the sources
I originally was looking at claimed) and if it does, how come that
extra pressure, on top of the already existing 12 psi heat pressure,
not cause the cap to blow off from the excess pressure now totaling
from 20 to 40 psi? All I can think is that the pump only adds perhaps
2 to 5 psi and that by the time it "gets" to the cap area, flow
resistance has dissipated it down to 1 or 2 psi and it has ceased to
be a problem. Or maybe the pump only "adds" negative pressure, i.e.
suction at the inlet, or some combo of all that.

[mike]

It's my contention that the pump can add no pressure unless it has
somewhere to get the water to pump.
If it's coming from the closed system, there ain't none available
unless you vaporize some on the source side.

[mike]

Can't argue with your theory. Problem is that it doesn't apply here
in any significant amount.
If the pressure exceeds the cap pressure, it vents.
The pump didn't add the pressure. In your scenario, the pump added
heat.
So, get back to the topic. In a closed car cooling system under normal
operation
can the pressure on the output side of the pump significantly exceed
the pressure on the input side?

I think we can exclude any vaporization of the liquid leading to excess
pressure. If it did, it would vent and, eventually, there'd be no more
liquid to pump.

But thank you for the clue and the hint and the nitpicking.

[cl...@snyder.on.ca]

The water pump can develop mabee a couple of pounds pressure on the
outlet side into a plugged rad with the cap off. With the cap on, with
no air in the system, significantly less. But at best, only a pound or
two. Will running the water pump dead headed cause a temp increase?
Sure, a very small amount. Inconsequential compared to the heat output
of the engine. It will NOT cause a pressure increase in the closed
system. The increased pressure increases the boiling point of the
coolant. It also helps get and keep entrained air out of the cooling
fluid. The only thing that causes the pressure rize is temperature.
The pressure reduces back to atmospheric when the temperature drops
back to room temperature. Current production vehicles have a "catch
tank" that holds excess coolant if any is forced out to regulate the
pressure, and it is drawn back in on cooldown.

[Rick]

"mike" <ham...@netzero.net> wrote in message

news:ljuo67$f5e$1...@dont-email.me...

Yes, and it looks like a lot of you have no idea how much it can, and does.

[mike]

I'd like to hear the rationale in a closed system.

[Rick]

"mike" <ham...@netzero.net> wrote in message

news:ljvhfb$c0h$1...@dont-email.me...

Simply put, it's a pump and there is a restriction on the outlet side. An
engine cooling system isn't a swimming pool with a pump in the middle of it.

[Guv Bob]

"MLD" <M...@verizon.net> wrote in message news:ljttbt$esc$1...@dont-email.me...

As the engine temperature rises, tiny gas bubbles start to form on the walls of the cooling cavities. The liquid changing to gas causes the pressure to increase. When the fluid is cold, the bubbles are condensed back into liquid right away and there is little pressure increase. As the coolant temp rises, it takes longer for them to condense, the volume of gas increases and the pressure increases.

[dpb]

On 4/30/2014 6:15 PM, MLD wrote:
>
> <cl...@snyder.on.ca> wrote in message
> news:qna9n89tjrmrielh8...@4ax.com...
>> On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "hrho...@sbcglobal.net"
>> <hrho...@sbcglobal.net> wrote:
>>
>>> On Apr 21, 6:11 pm, Tony Hwang <drago...@shaw.ca> wrote:
>>>> Ashton Crusher wrote:
>>>> > I was thinking of putting a higher pressure cap on one of my cars to

>>>> > increase the factor of safety against boiling. ...

...

>>>> > Thought I'd see if anyone else has heard of this. The claim was that
>>>> > the water pump could create over 30 PSI of pressure. Since that is
>>>> > double the normal operating pressure of most modern cars I find it
>>>> > hard to believe. If the system was at full 15 psi of pressure while
>>>> > the car is idling and then your floored it and ran it up to near
>>>> > redline and created another 30psi of additional pump pressure, or
>>>> > even 10 psi of additioingnal pressure downstream at the radiator
>>>> cap, > you
>>>> > would immediately cause the system to have to vent to the overflow to
>>>> > relieve this higher pressure. I've never seen a car vent due to me
>>>> > revving the engine up while I'm working on it. Thoughts?????

...

What the limit is of how much pressure the water pump can produce is
based on the pump design and I really don't know what those values
typically might be. But, the pressure in the system is controlled by
the pressure cap. There's a very good description at the following link...

<http://books.google.com/books?id=xLxySLNAe3YC&pg=PA136&lpg=PA136&

dq=does+radiator+cap+control+radiator+pressure&source=bl&ots=--_LIFglKt&

sig=vhm95_RJG8vWT6iJMsaY-3OAGmM&hl=en&sa=X&ei=FdNjU-SuJfP7yAGho4CwCQ&

ved=0CIgBEOgBMAg#v=onepage&

q=does%20radiator%20cap%20control%20radiator%20pressure&f=false>

--

[Rick]

"dpb" <no...@non.net> wrote in message news:lk0kf0$kdr$2...@speranza.aioe.org...

30 psi is putting it mildly....

[MLD]

"mike" <ham...@netzero.net> wrote in message

news:ljuo67$f5e$1...@dont-email.me...

Once more---A centrifugal pump--that's what is in your car--the pump
discharge pressure is a function of the pump speed squared. Once the
thermostat opens there is a flow path from pump to radiator back to the pump
inlet. Other than a slight droop in pressure due to the flow demand, the
pressure rise across the pump basically constant. Obviously, no venting
occurs as long as the pressure at the radiator is less then the cap pressure
setting. Pressure at the radiator is established by whatever line loses
there are between the pump discharge and radiator. Venting occurs because
as the coolant temperature increases it's volume will also increase. Why??
Density=Weight/Volume.
Density decreases as temperature increases. Since the weight of the coolant
doesn't change, it's the volume that does.
As the coolant expands, the pressure in the system increases (remember,
trapped volume aka closed system) and when the pressure gets to the cap
setting (won't take long), the cap opens and the fluid goes into the
overflow bottle. If the radiator cap didn't open--whole new
scenario--things would break!!
If this doesn't answer your questions, suggest you do a bit of reading on
your own.
MLD

[cl...@snyder.on.ca]

On Fri, 2 May 2014 00:08:20 -0400, "Rick" <itsno...@gmail.com>
wrote:

The difference in pressure across the pump is equal to the difference
in pressure across the radiator. Suction on one side, pressure on the
other. A matter of a few psi with a good rad and the thermostat open.
The pump is not capable of producing very high pressures.. The
pressure on the low side can be up to 5 psi below nominal, and on the
high side as much as 5psi above no

[cl...@snyder.on.ca]

Restriction to flow affects the "head" of the pump. No restriction,
no head pressure. A good water pump may produce a 5 psi head, and draw
an equivalent depression on the low side of the pump for a maximum
pressure differential of 10psi - but that is a "blueprinted" pump at
optimal speed with an adequately restrictive radiator.

Real world numbers are generally quite significantly less. Measured
3psi on BMW 328 just this week at 3000 RPM. Above and below 3000 it
dropped off. That was with diluted coolant (about 20-25% glycol) due
to having just repaired a leak and having the normal "fun" bleeding
all the air out of the nasty little Kraut!!

[Ashton Crusher]

Your comment makes no sense to me. There is always water at the
inlet to the pump if the system if full of water. You can see the
water moving if you take the cap off, at least on some systems where
it opens into the tank. Clearly the pump is pumping water, therefore
it's getting some to pump and it's certainly not as vapor.

[Ashton Crusher]

Where in the system did you take that 3 psi measurement at?

[Ashton Crusher]

My little 1.5 hp swimming pool pump, with similar sized centrifugal
impeller to a car, similar sized pipes as a radiator hose, and running
at a couple thousand rpm can easily produce over 25 psi if you shut
down the outlet valve. It seems likely to me that the water pump in a
150 hp car could do the same if the flow was restricted.

[Guv Bob]

"MLD" <M...@verizon.net> wrote in message news:ljs061$dvo$1...@dont-email.me...
>

MLD, do you know where to find a flow rate vs RPM curve for any common stock water pumps? I'm surprised I can't seem to find anything mfr spec curves at the various mfrs and parts houses. Doesn't matter what mfr or vehicle -- just any common street car single head pump.

[Ashton Crusher]

I was looking to see what I could find on water pumps and didn't find
much. I did come across this
http://teae.org/cooling-the-tiger/
which is pretty interesting though. A bunch of home experiments
looking at what things make for better cooling.

[Guv Bob]

"Ashton Crusher" <de...@moore.net> wrote in message news:gi46n9temjlhe423h...@4ax.com...

Thanks, that's very interesting info. I'm not familiar with the particular car they are doing the testing with, but it seems odd to me that they consider coolant temps below 212 deg F as normal. They must be water with no glycol in a system open to atmosphere. However, I didn't read it that closely thought so (as most people say) I may be off.

[cl...@snyder.on.ca]

On Wed, 14 May 2014 23:43:00 -0800, "Guv Bob"

Below 212 is normal. Anything over is abnormal, but still safe untill
the BP of the pressurized mixture is exceded. Normal Operating Temp is
closer to 195F-215F

[MLD]

"Guv Bob" <guvbo...@yahooooooooooooooo.com> wrote in message

news:1aydnRp1JJ2xBO_O...@earthlink.com...

Found this Flow vs Delta P characteristic.
http://www.bing.com/images/search?q=auto+water+pump+flow+curve&qpvt=auto+water+pump+flow+curve&FORM=IGRE

MLD

[Guv Bob]

"MLD" <M...@verizon.net> wrote in message news:ll8s0t$f3k$1...@dont-email.me...

Thanks. Still looking for RPM vs Floweret

[MLD]

"Guv Bob" <guvbo...@yahooooooooooooooo.com> wrote in message

news:LbqdnbslHIkuZeHO...@earthlink.com...

You're right, not an easy thing to find. Why not give one of the many
manufacturers a call and ask for what you want.
MLD


>

[Rick]

<cl...@snyder.on.ca> wrote in message
news:9sp7m9pcto58nb72q...@4ax.com...

Having performed thousands of automotive cooling system flow/pressure and
pump performance tests, I can say you have no idea, either.

Without getting into particulars, recently....5500 pump RPM...10 psi at the
pump inlet, 200+ GPM into the block at 80 PSI pump outlet pressure