Cracked block?

The car is a 1995 SW-2. I removed the oil filler cap while the engine
was idling, and pressurized exhaust gas was emitted through the
opening. Oil filler cap contained emulsion, and white vapor has been
coming from the tailpipe upon start-up, which btw has been sporadically
difficult (acts like a flooded engine). What would cause the space
under the valve cover to become pressurized by exhaust gas?

 

Usually it is worn/bad piston rings for the pressure and water vapor
is normal (depending on the amount of it) YOu could pressure check
the cooling system and check for a bad head gasket or cracked head too
but this would not likely pressurize crankcase and make sure PVC valve
is working and not plugged up too.

 

Blow-by past the piston rings?

Ken

 

sounds like a blown head gasket

 

Could well be.

 

Yeah - he wrote me in email. Said there's oil in his coolant too.
Definately AT LEAST a bad head gasket - possibly even a crack in the
cylinder head.