[Vwdiesel] head gasket needed?

[Marvin Jansen]

My 85 1.6na is blowing antifreeze from the rad cap and seems to get
hot, over the 3/4 on the temp guage on a cold day after driving 30
minutes or more..  Maybe it's just the cap I got from O Reileys
leaking .  It's a German cap, but maybe a VW cap is a different
pressure or something. How can I check?  There is no apparent oil in
the water and no water in the oil.  The temp light is still coming on
sometimes, but after shutting off the engine while still rolling and
starting back up the light stayed off the last 20 minutes of the trip.