Ruby Radiator Water Level

[Alan]

Agreed. Boiling in itself isn’t a problem. It’s boiling dry that is.

["Slack Alice" Simon]

I agree with Hedd - they find their own level, which looks too low for comfort, but seems to work perfectly well.

[Colin Morgan]

That's reassuring, but surely not as Austin designed it to work?  Has anything changed?

[Ruairidh Dunford]

How far from the top of the filler is the overflow pipe?

[Steve kay]

Hedd has certainly reported my experience. Once the car has been used, any overfilling has been sent down the overflow, and as long as all joints are kept watertight the level should be fine. It is not high in the top of the radiator when cold, but fetching the oven gloves from the kitchen just after a journey will allow the curious owner to observe the effect of water expansion. Possibly part of being able to spot and be a bit anxious about water levels is a result of Fernox and clean water. An old fashioned cocktail of rust and anti-freeze would obscure the sight of the upper radiator core.

Reports on boiling are interesting. Whatever the oil un-tightness of the Ruby's current engine, the combination of cleaned out water passages and a much improved radiator have meant consistently low running temperatures. This summer, on some very hot days and ascending some very steep hills, the Ruby has come nowhere near boiling. I've only seen the temp gauge pass 90 degrees once. Currently all bonnet louvres are shut, and a muff will be seriously considered before frosty driving arrives.

[Reckless Rat]

I am sure a lot of problems with overheating are down to the state of the radiator or engine block. I have just completed an 8 day 2000 mile trip in my RP, running at 45mph most of the time and the run included crossing the Pyrenees twice. It involved several long and high climbs (the highest was 2404 metres). Ambient temperature was between 26 and 28°C. The car never overheated and the water level remained constant throughout, sitting (when cold) at the bottom of the semi-circular moulding in the filler neck. If I topped it up any higher it would just drip out of the overflow.

My radiator cap is "sealed" with some clear silicone to prevent splashing out of the top. The car has a four blade fan.

[Steve kay]

Good heavens, an RP manages to cross the Pyrenees twice at 45mph! My grossly overweight Ruby often needs second gear to get up these slight bumps in the Black Mountains. Chapeau indeed, sir.

[Tony Griffiths]

No loss water system  Terry.

Ready-made, ready to go - and about the right size?  https://www.ebay.co.uk/i/302852130996?ch...gL9rfD_BwE
..and cheaper, a second-hand motorcycle unit: https://www.ebay.co.uk/sch/i.html?_from=...cat=177962

[Reckless Rat]

A little poetic licence on my part there. I was cruising at 45mph on the flat bits. Climbing in the RP was in 3rd gear, usually at 25-30mph. Never once had to go down to second on any of the climbs. Box is 4speed crash. The ratios are slightly different to the later synchro ones. 3rd is 1:1.73 in the RP and the Ruby box is 1:1.66 so you might have to resort to 2nd on the steeper bits. The problem with the 4 sp crash is that if you have to go for 2nd you're stuffed until it flattens out a bit and you can get enough momentum up to get back into 3rd before you lose the speed again.

[Colin Morgan]

The top of the overflow is only 1/4" below the top of the filler neck. 

While I was out measuring this, I took some other measurements.  The current water depth (cold) in the top tank is 3/4".  An ideal level would seem to give a depth of about 1 1/2" - so actually only 3/4" difference - not as much as I thought - and with the thermal expansion from garage to working temperature it would perhaps be a bit less (by about 1/4"?) when hot.

The volume of water needed to raise the level from 3/4" to 1 1/2" is only about 3/4" x 12" x 4" = 36 cu inches.

This is equivalent to about 600cc or 0.6kg of water, which has the capacity to absorb 4200 x 20 x 0.6 = 50,000 joules if raised from a normal working temperature of 80 C to 100 C.  Whilst 50,000 joules might sound a lot, it is the equivalent of only 1kW (1.4 horsepower) for 50 seconds - not much of a buffer against the engine working harder on a hill. 

Seems that circulation is the key to cooling, and 3/4" in the top tank is plenty for that.

Colin