Vixen cooling

[Moto]

Does anyone know how the Vixen S3 (Crossflow) cooling system was originally designed. I have the original radiator still fitted with a small diameter outlet pipe in the neck just below the pressure cap. This has always just been into fresh air.

I don't have any issues with this arrangement but would like to know if there should be an expansion / header tank that has been lost at some point. If so how should this work and is there any downside to not having it.

Moto

[NicBowman]

Hi Moto.

Just from general knowledge of other 60s cars, this is normal. If the cap yields, the water just passes out down the pipe to the floor. The expansion gap exists in the top of the radiator.

Best


Nic

[phillpot]

NicBowman said:

Just from general knowledge of other 60s cars, this is normal. If the cap yields, the water just passes out down the pipe to the floor. The expansion gap exists in the top of the radiator.

[Moto]

That's helpful thanks.

It explains why I can always top up the rad with 1/2 litre. As you say the top of the rad acts as an expansion tank and therefore will expel some water to facilitate that.

I intend to fit a catch tank as scrutineers don't like to see any fluid dripping onto the track. I presume if I run a hose from the rad neck outlet to the base of the catch tank, mounted lower the rad outlet, that would be fine.

If this is done would the rad then suck expelled coolant back into the rad as it cooled?

Moto

[phillpot]

Moto said:

T

If this is done would the rad then suck expelled coolant back into the rad as it cooled?

Depends if you rad cap has a return valve?

[NicBowman]

I suspect not. With an expansion tank the rad cap is a blank, no pressure element. The expansion tank has the pressure cap. The expansion tank still has a drain…. Just the same.

A pressure yielding cap does not normally suck anything back in.

Just put the overflow into a bucket! Small one.


Nic

[TwinKam]

NicBowman said:

I suspect not. With an expansion tank the rad cap is a blank, no pressure element. The expansion tank has the pressure cap. The expansion tank still has a drain…. Just the same.

A pressure yielding cap does not normally suck anything back in.

Just put the overflow into a bucket! Small one.


Nic

Some 'overflow' systems do have a pressure cap on the rad, but the cap has an upper seal as well as a two-way pressure valve. On expansion, excess coolant is expelled via the 'exhaust' valve into a tube that goes right to the bottom of an overflow tank (open to atmosphere). Upon cooling, that coolant is sucked back into the rad via the lightly sprung 'inlet' valve.

[LLantrisant]

with such old systems the radiator´s upper chamber acts as expansion tank. means you should never fill up the rad comepletly.

if you want to do this and add an expansion bottle its quite easy:

use a radiator cap with 2 gaskets (one that seals towards the chamber and one which seals on the top (at the bayonet lock).
the overflow pipe ends in a open-bottle (the pipe must go up to the lowest point of the bottle).
e.g. RADIATOR OVERFLOW BOTTLE & CAP KIT ; SPITFIRE MkII-1500 '64-'80
the bottle can be installed wherever you want...you dont need to espect a certain level inside the enginebay.




when the water gets hot and expands the valve in the radiator cap will open...the water will be psuhed into the bottle.
when the water gets cold and shrinks (overnite in your garage) it will form a small vacuum inside the cooling system and the valve inside the cap will allow to suck-back the expelled coolant from the bottle.

[GeneralBanter]

The Tuscan uses a plastic expansion bottle which works really well in shifting the fluid both ways. Its the Rover/MG RV8 version of the old brass thing that Midgets/MGB's used.

[Adrian@]

Steve, choose your expansion bottle wisely...not all expansion bottles are equal...I have been adding the internals to BL brass expansion tanks for years... dependant on how they are mounted on the original car depends on the tanks ability to draw back fluid.

A@

[LLantrisant]

GeneralBanter said:

The Tuscan uses a plastic expansion bottle which works really well in shifting the fluid both ways. Its the Rover/MG RV8 version of the old brass thing that Midgets/MGB's used.

this is a differtn story....as this "bottle" has a pressure cap...in correct technical-terms it is not an overflow-bottle, its an expansion-tank.

its not the one to be used for the above decribed topic.

[GeneralBanter]

LLantrisant said:

GeneralBanter said:

The Tuscan uses a plastic expansion bottle which works really well in shifting the fluid both ways. Its the Rover/MG RV8 version of the old brass thing that Midgets/MGB's used.

this is a differtn story....as this "bottle" has a pressure cap...in correct technical-terms it is not an overflow-bottle, its an expansion-tank.

its not the one to be used for the above decribed topic.

…albeit exactly what was being discussed!