Sealed(?) cooling system

[Eric Aldcroft]

This may seem rather trivial; but it took me a while to get there -- so perhaps it could be useful to others! There is a description in the JCC Owners Handbook (P. 75) by J.Harvey of the installation of a screen washer bottle to create a "semi-sealed" cooling system. My problem with this description was that I couldn't see how the coolant would find its way back into the radiator on cooling, through the pressure valve in the radiator cap. So, I took my spare cap apart and drilled a 5/64" hole in the disc that is in effect the valve. I obtained a 1 litre capacity coolant reservoir off an old Toyota that fits nicely in front of the carburettor tube. I've tested the system while idling in the garage when the coolant got up to about 90°C, and also on the road -- and to my delight it seems to work very well. The 1 litre capacity of the reservoir is adequate. I'm not sure if my cooling system is pressurized any more, since the Toyota reservoir also has an overflow, which is perhaps pressurized slightly by a sort of rubber gasket or valve in the cap.

[Forumadmin]

On my jup the overflow was always connected to a bottle; so that if it did overflow the fluid was saved and could be manually restored. Occasionally used on those Alpine hillclimbs; but not needed with the aly rad.