Classic cars forum & vehicle restoration.

[Jason]

just been out in the Alvis, only did a couple of mile but warmed her up before going.
the temperature gauge shows about 60 degrees when the car is moving and when the engine is running at idle.......thats fine but,

I've just noticed that when I switch the engine off and leave it a for a few minutes the gauge goes up to 70 degrees before it drops, as it cools.

is this normal

btw its a capillary gauge.

jason


the wifes just said it'll be because the fans stopped going round........could that be what it is?
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"people with money buy a Rolls Royce, people with taste buy an Alvis".

[Rick]

I remember my 2.5 Spitfire used to do that, I suppose as soon as the coolant stops circulating there may be some further heat soak (?) from the block into the coolant, raising its temperature before it begins to cool again..?

R
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[47p2]

As Rick says, it's heat soak. My P2 does exactly the same thing and if the radiator is overfilled it will spit the extra out when I stop
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ROVER
One of Britain's Fine Cars

[Jason]

thanks lads, mine spits it out too if its overfilled.

jason
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"people with money buy a Rolls Royce, people with taste buy an Alvis".

[47p2]

You'll possibly find that the gauge rises further on a warm day and when you switch the engine off the gauge will rise almost to 100.
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ROVER
One of Britain's Fine Cars

[Jason]

cheers p2, I won't worry too much about it anymore

jason
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"people with money buy a Rolls Royce, people with taste buy an Alvis".

[bob2]

Jason you could fit some sort of bottle as an overflow reservoir, you could hide it under a wing and just pass a pipe from the rad to it, just place it more or less level to the rad and put a long pipe that will almost touch the bottom of the bottle, that way you will not need to top up the rad every now and then.

I've done it on my minis and its fine, before hand used to check the coolant level evreytime I was going for a ride, but now the radiator is always filled to the top.

[Jim.Walker]

The water in the block and particularly the cylinder head will always be hotter than the water in the radiator. Hence thermo-syphon cooling works because hot water rises. On older cars there is usually a marked upward lie to the top hose even when a water pump is fitted, and the temperature gauge is usually around the highest point. Hence you are seeing the effects of thermo-syphoning. Modern thermo-static gauges don't move fast enough to see the change even if it happens. In any case electrical gauges "die" when the ignition is switched off.
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