Radiator cap

[Chuck Wheeler]

As I remember form a automotive class in 1970, about the time all this
emissions stuff was getting started, in order to meet some of the
requirements it was necessary to raise the average combustion temperature
while lowering the peak temperature. This "average" temperature was
approaching the free air boiling point of the coolant so in order to raise
the boiling point of the coolant, in many cases still only water, the
coolant pressure had to be raised. Diesels were not subject to these
regulations and they use larger volumes of coolant and dual valve
thermostats which maintain a higher coolant velocity to reduce hot spots.
This was not really an option for automotive engines because of economics,
weight, and the idle cycle emission criteria.

- Chuck Wheeler -
82 FC 31 SB
Fort Worth, TX


_____

From: WanderlodgeForum@yahoogroups.com
[mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of badbillybiker
Sent: Thursday, January 18, 2007 10:05 AM
To: WanderlodgeForum@yahoogroups.com
Subject: [WanderlodgeForum] Radiator cap



Hello...
Just my longwinded $.02 worth...
A long time ago when car companies werent' so dam greedy... the
radiators were by today's standards... "heavy duty".
Back then the radiator had more than enough capacity under normal usage
that the cap was just that... a cap..
When corporate greed started kicking in... (worse than it was)they
finally figured out that by making skinnier and cheaper radiators, they
could get away with it by finally making the cap & system pressurized.
It goes like this... the stronger the spring, the higher the pressures
are and...the thinner the radiator gets until they are at the current
compromise... greediness, cheapness and of course selling you more
expensive anti-freeze. Back then you could put ordinary alchohol,
kerosene or ... a methanol based antifreeze (as in cheap stuff) but as
the pressure rose, so did the temperature which would boil out the old
time (cheap stuff) If my memory hasn't failed.. I believe that @ 13
pounds you are in the super-heated range past 212 degrees. When the cap
is now removed the fluid expands and wah-lah... boil over...
Hmm... I think it was for every 1 pound cap pressure, the radiator
could get hotter by 10 degree before blowing...
Some of the memories are getting a bit foggy now but the lesson is
there... I am presuming that due to the nature of a deisel motor, your
radiator is quite large in capacity and you, in using a 7-9 pound cap
have been getting away with it because you haven't pushed your unit..
Wanna' really test your 7 pound cap out... find a long steep grade and
watch the needle climb... Finally the thermostat is NOT a radiator cap,
that is for engine temperature regulating. Of course this article is
subject to bashing etc. PS: My 1950 merc had a no pressure cap and yes,
you could drive without it...radiator was 3 or more inches thick...
Bill.. FWIW...
Get the right mandated cap!






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