water temperature

[Thowdfella]

I have a 1938 Austin Big seven which came with a capillary tube type water temperature gauge which didn't work. I have now installed my Christmas present - a new capillary gauge and sensor and been out for a run. going along at about 35mph the temperature was 90 degrees C and as the outside temperature was around 4 degrees I became concerned as to what the temperature would be on a hot day in summer. 90 degrees is around the centre of the scale on the gauge but as water boils at 100c its not that far off - unless the boiling point is different when under pressure. Can anyone advise please?

[Reckless Rat]

Sounds dead right to me. It what my modern settles at, and them Germans know what they're doing.

[Phil Kingdom]

Water boils at 100 C at sea level, but the boiling point goes up the higher the pressure in the system at say 4PSI the boiling point is about 107 C and any additives in the system will also help raise the boiling point.

[Chris KC]

(Is the Big Seven system pressurised?)

I didn't want to 'pour cold water' on the OP's Christmas present but the last gauge I tried read about 10% low anyway; and took a frightful long time to respond to any change. I kind of gave up on temperature gauges myself, but I guess you can view it as a general indicator of engine wellbeing (or otherwise). In which case the thing to do is observe what it generally indicates (whatever figure that may be) and watch out for marked deviations - don't fixate on the absolute value because as Phil rightly says, the 'limit' is not a fixed number!

[Ruairidh Dunford]

Several friends fitted temperature gauges to their cars last year - both experienced alarm at how high the car ran.

Neither had anxiety before the gauges were installed.

[Steve Jones]

Several friends fitted temperature gauges to their cars last year - both experienced alarm at how high the car ran.  

Neither had anxiety before the gauges were installed.

In another thread last night I referred to the P Type Lea Francis I used to own. These have Meadows 4ED engines that tend to run a touch on the warm side anyway and the Calormeter on the radiator always showed a reading that was a bit higher than I would like although the engine never boiled in normal use. Eventually, for other reasons, the time came for a new radiator and once fitted, I assumed, as a by-product, the car would run a little cooler. Made no difference. I removed the Calormeter. The problem went away. 

Steve

[Reckless Rat]

Several friends fitted temperature gauges to their cars last year - both experienced alarm at how high the car ran.  

Neither had anxiety before the gauges were installed.

In another thread last night I referred to the P Type Lea Francis I used to own. These have Meadows 4ED engines that tend to run a touch on the warm side anyway and the Calormeter on the radiator always showed a reading that was a bit higher than I would like although the engine never boiled in normal use. Eventually, for other reasons, the time came for a new radiator and once fitted, I assumed, as a by-product, the car would run a little cooler. Made no difference. I removed the Calormeter. The problem went away. 

Steve

So true, Steve. Gauges and warning lights are just more things to worry about. Ignorance is bliss.

[Colin Morgan]

Hi

A few years back I fitted a temporary gauge (thermocouple) to my late '38 Ruby and found it was running at about 90 degrees C on an average day.  Trying the gauge again on a hot summer's day, it was only a couple degrees warmer.  Also, the late Ruby system is slightly pressurised - there is a relief valve fitted before the overflow - so 100 degrees is not the boiling temperature even with fresh water - it will be higher - and the 30% anti-freeze will also raise it.  In practice, my car has never boiled when there has been enough water to allow circulation.

So I have stopped worrying about it, other than checking the water level.  (One thing that might help counteract the age of the radiator core is that it is the straight-through channel type, rather than the original zigzag - this later one being more efficient?)

Colin

[Steve kay]

A slightly belated response, but my Ruby used to merrily boil at the top of a steep hill. The engine back from Steve Flake and the radiator from Hereford Radiators, the newly installed temperature guage tells a very different story. With properly cleaned out circulation, running is now almost cool. Last summer ascending a chevron or two, three up, came nowhere near boiling. None of our cherished suppliers seem to be listing  a radiator muff, and I've never got to an autojumble early enough to find one, so I'afrait it's ali foil at the moment.

[Chris KC]

My car had been running progressively hotter over a period of some years. Before stripping it down I ran a descaler through the system (got it from Halfords, forgotten which one). On disassembly I found the side manifold about 80% blocked with semi-solid crud. Part of my rebuild included winkling coat-hanger wire inside the block waterways as far as I could get it, and copious flushing of block and head. I rather suspect it will run a bit cooler now!