Hi,

1993 945 Turbo. Symptom: Coolant fluid low in coolant tank after driving. When opening cap coolant comes back up rapidly into coolant tank, to original level, corresponding to abou the seam between upper and lower coolant tank sections. When, after driving, feeling upper rubber hose between block and radiator pressure seems pretty high, but perhaps not much more (??? this is pretty difficult to judge, I don´t have a sensor/gauge setup at hand) than the 150 kPa (=1.5 atmospheres) marking on the green coolant tank cap. The radiator, hose and tank cap was changed about year and a half ago. Before that, I had a grey cap and had the feeling I was slowly loosing a bit of fluid.

What is my problem? Has my realtively new green cap started acting up, not letting off pressure? What is the pressure rating of grey and black caps, should I go back to one of those?

Should I fill up reservoir even more? Do I have a wrong type of rubber tubes between block and reservoir (they seem to be the place where the coolant fluid goes when pressure builds up)???

Do I have a head gasket problem? If so, I would assume I should see loss of fluid or presence oil in coolant. No evidence of those symptoms.

Could I have a problem with my thermostat??????? (Temp meter rock steady straight up when driving, so I would not primarily assume a problem there). Havent touched thermostat in the six years I have had car.

Many thanks in advance for inputs!

Gustafkalle.