>1) head gasket gone, coolant drips to ground, overflow tank is unaffected
>2) ditto, gases get into coolant while running, overflow tank fills
>3) ditto, coolant gets into cyls while cooling, overflow tank empties
>
>In all cases overheating/air buubles eventually occur. #3 happens as the 
>engine cools, leads to short period of rough idle on start-up. This was sent 
>a while back by another poster. As it gets really cold it sucks in from the 
>overflow?
>
>Are there any more modes/combos for head/coolant failures, are the ones 
>above really true? My '87 has already drunk a jug of Autobahn (in 2 months), 
>without leaving a trace so I'm assuming #3 is at play.  tim s.

not to deviate from your topic too much, but i was curious, what is 
observable on the engine which would indicate problems with the head 
gasket/cooling system? TIA