When hot, coolant's air bubbles appear / expand, so coolant always got
pushed out of cap & into overflow-bottle.
I put a o-ring onto cap's bottom seat for cap's gasket to press onto, to
increase cap's spring's pressure on coolant, www.barsleaks.net/faq.html
then engine( F20A )'s maximum*temperature is lower, I think because
air bubbles are now smaller so heat can be transferred out fstr : now *
does not ( used to ) reach the top left corner of my '90 accord ( tmprtre
gauge lacks calibration ) 's gear position indicator's D3 box, in 29°C
ambient air .
Users in hot weather e.g. http://msnbc.msn.com/id/8641667/ beware.

Does any1 here put distilled water in radiator ? Can distilled water (
w-o air dissolved therein ) transfer heat fstr than tap water ( has air
dissolved therein ) ?

 

If you have bubbles in the coolant, then you have a vastly more serious
problem than the radiator cap. Possibly a blown head or manifold
gasket that is permitting exhaust gas to leak into the cooling system.
It is absolutely NOT normal to have any bubbles in the coolant...given
no internal leaks, dissolved gasses are driven off in the first couple
of minutes of normal operating temperature after a fill.

 

| Possibly a blown head or manifold gasket
Other symptoms will appear, if either gasket cracked.

| dissolved gasses are driven off
To where ? They cannot escape when radiator cap is closed, & will re
-dissolve into coolant ( when cool ), esp CO² ( quite soluble in cool
water ).

| normal operating temperature
Pls define.
My brother's Mercedes 280 has a maximum water temperature of 79°
C, but his C200 - 90°C. Japanese cars' tmprtre gauges lack calibration
, I can only guess what their water's max tmprtres are.

 

"TE Cheah" <no@spam.biz> wrote in message news:43f8b575_2@news.tm.net.my...
> | dissolved gasses are driven off
> To where ? They cannot escape when radiator cap is closed, & will re
> -dissolve into coolant ( when cool ), esp CO² ( quite soluble in cool
> water ).
>
>
Under normal conditions the coolant cycles to/from the reservoir when the
engine is run. Whatever bubbles collect in the radiator should get cycled
out to the reservoir each time the engine warms up. I am more than a little
concerned if bubbles appear on a continuing basis more than a few days after
the system is filled. OTOH, if it is the head gasket dying the symptoms will
soon come on strong, as you say. Within a month or so you should know one
way or the other.

A common shadetree check for head gasket failure into the coolant passages
is to remove the radiator cap (with the engine cold), start the engine,
pinch off the hose to the reservoir and place the palm of your hand over the
radiator opening. If combustion gases are leaking into the coolant you will
feel the steady rise of pressure against your palm within a couple seconds
and there will be no mistaking the pressure within less than 10 seconds. By
the time you can feel fluctuating pressure the gasket is very far gone - I
don't recall feeling that on a car that still ran.

Mike

 

| Whatever bubbles collect in the radiator should get cycled
| out to the reservoir each time the engine warms up.

Only if cap ( like my Toyo cap ) puts too little pressure on coolant
, & coolant gets hot enough for bubbles' pressure to exceed cap's.
Even then, not all bubbles will escape ; when bubbles escape,
remaining bubbles' pressure will drop til < cap's, then no more
bubble will escape.

 

On Mon, 20 Feb 2006 17:12:30 +0800, "TE Cheah" <no@spam.biz> wrote:

>| Whatever bubbles collect in the radiator should get cycled
>| out to the reservoir each time the engine warms up.
>
>Only if cap ( like my Toyo cap ) puts too little pressure on coolant
>, & coolant gets hot enough for bubbles' pressure to exceed cap's.
>Even then, not all bubbles will escape ; when bubbles escape,
>remaining bubbles' pressure will drop til < cap's, then no more
>bubble will escape.

The amount of pressure your cap provides is directly correlated with
he temperature at which it is intended to open. The is technology
from, oh I'm guessing, the 1920s. All of the dissolved gas is quickly
vented form the system and, if any remains, it isn't causing a
problem.

I cringe to ask what you think the problem is here.