Date: Mon, 9 Sep 2013 15:04:50 -0700
Reply-To: Tom Carchrae <tom@CARCHRAE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Tom Carchrae <tom@CARCHRAE.NET>
Subject: Re: A Different Coolant Problem
In-Reply-To: <CAFnDXk2ASfnarqyAFE0GYmSKTTgrSxBSWVrzFwbDU8WMg03Tjw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Sure. And no doubt that steam in the engine is a nasty cycle, with
air/steam pockets creating more/bigger hotspots.
However, once cooled, if there are no combustion gasses, then all the steam
should disappear, right? When that happens, it will draw coolant back in
from behind the licence plate. The only time it could leave air is if (a)
it was combustion gases or (b) if the tank behind the plate was empty, or
(c) the cap or pipe (to the reservoir behind the plate) has a hole.
On Mon, Sep 9, 2013 at 2:42 PM, Jim Felder <jim.felder@gmail.com> wrote:
> Yes, but only after it had displaced a great deal of coolant.
>
> Jim
>
>
> On Mon, Sep 9, 2013 at 4:18 PM, Tom Carchrae <tom@carchrae.net> wrote:
>
>> Great explanation Mark. Thank you.
>>
>> If the "air" is indeed steam, then wouldn't it return to liquid form once
>> the system cools?
>>
>>
>>
>>
>>
>> On Mon, Sep 9, 2013 at 1:59 PM, mark drillock <mdrillock@cox.net> wrote:
>>
>> > There are 2 major choices for the "air" that appears to force the
>> coolant
>> > out into the overflow tank in your case. Either you have a hot spot
>> that is
>> > boiling the coolant and making steam, or you have some failure that is
>> > letting high pressure combustion gases seep into the cooling system and
>> > displacing the coolant. A third variation would be if you were foolishly
>> > running straight water then steam is going to happen much more easily.
>> The
>> > coolant 50/50 mix doesn't boil until it is about 50 degrees hotter than
>> > straight water does. If the cap is bad and you are running straight
>> water
>> > then that is a double whammy since a pressurized system raises the
>> boiling
>> > point. A leaking cap valve reduces the system pressure so boiling is
>> more
>> > likely to occur with a bad cap.
>> >
>> > Whether the "air" is combustion gases or steam, its source location is
>> > away from the coolant tank. So when it first appears in the system it
>> adds
>> > rapid pressure to the system that will want to escape somehow. Typically
>> > the pressure will escape through the overflow nipple of the cap and into
>> > the overflow tank, pushing liquid out since that is what is in the tank
>> at
>> > that moment. The "air" will later end up gathered at the main tank. If
>> it
>> > had originated at the main tank it would be the first thing forced out
>> the
>> > cap nipple but that is not the case. Thus the source is elsewhere.
>> >
>> > Mark
>> >
>> >
>> > Tom Carchrae wrote:
>> >
>> >> This is not a different issue - this is my cooling issue.... :)
>> >>
>> >> I have a question to ask the experts regarding the bad cap theory. I
>> get
>> >> how the fluid ends up in the overflow tank - but if it just a cap,
>> where
>> >> does the air/gas come from the displaces the coolant - and why does it
>> not
>> >> pull the coolant back into the pressure tank when it cools?
>> >>
>> >>
>> >>
>>
>
>
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