> "Fanie" <firstname.lastname@example.org> wrote in message
>>Does anyone know off hand the boiling temp of a Disco 300tdi circa '96. I
>>have fitted a hewitt industries engine protection system but I find the
>>engine temp warning coming in a little early.
>>I know toyota consider a cooling test to be a fail if they get within
>>10degC of the boiling point of the cooling system so I would like to get a
>>new sender that would kick in at about the same level ie 10deg cel below
>>system boiling point.
> Well, assuming your cooling system is pressurised to 14.7 psi, (1 bar) the
> boiling point will be 100 degrees. For every 1 psi over what you have now,
> will raise the boiling point by 1 celcius.
> Alistair >
A little expansion of Alistair's explanation may help.
At a 'normal' atmospheric pressure of 14.7 psi, (1 bar), water will boil
in the open at 100 deg C (If you live at 5000 ft the boiling point will
be somewhat lower.)
Engines run with pressurised cooling systems - typically either 7, 13 or
15 psi higher than this 14.7 psi. Using Alistair's 1 degree for each 1
psi above normal atmospheric pressure, water in a 13 psi system will
boil at about 113 deg C
Most cooling systems, however, are not filled with pure water but an
antifreeze/water mixture. This itself has an elevated boiling point
compared to pure water. A 50/50 ethylene glycol/water mixture boils at
around 106 deg C at normal pressure and at around 125 deg C with a 13
This 125 deg C figure is probably what Stephen was looking for and comes
with all the usual disclaimers as to its accuracy. Check the numbers
yourself! The 300TDi, I think, normally runs with a 15 psi pressure cap
so there is already a margin of safety in the numbers that I have quoted.
(There are many antifreeze manufacturers' sites on the internet which
carry this sort of information. This is typical:
Try a search including boiling point, antifreeze and pressure)