Leaking radiatorcap

I have a problem!
The radiatorcap is leaking when I turn of the engine. Not while running! (I think!)
It is not overheated, the temperature is 78 celsius.
The thermostat is new, and so are also the radiatorcap.
I think that the waterpump is OK, but I'm not sure.
Could it be the radiator?
Please help!

 

check the neck where the radiator cap fits. see if there is any
cracks in the bottom of the neck. that might be your problem!!!!!!!!

 

Neck

Nope! It's leaking trough the overflow-hole.

 

hot

are sure that the rad is not merely overflowing
into the overflow container ? when u shut off the motor, the engine temp will rise, the coolant
expands and overflows in the overflow container .
this a a normal procedure .
gerry

 

hot

Is it standard with overflow container on the 68' Skylark?

 

No, pre 70 did not have one standard... however a 70+ iseasily adapted into the 68/69 and looks good too...