TVR Tamora - spitting out coolant

[michielp]

Hi,

My Tamora has no expansion tank, only the swirlpot.
If I fill it till about an inch under the neck (as the manual says), if it gets hotter around 90 degrees it will start spitting out coolant via the blue cap.

Is that due to it being overfilled? because it expands and need to go somehwere.
How to determine the right amount of coolant in the swirlpot?

Is there a kit available to add an expansion tank, any tips?

regards Michiel