the other day when i was changing the oil in my car, when i loosened the oil cap there was a hiss sound when i turned it. it sounded like pressure releasing. the car was warmed up and everything. i havent heard this noise before when loosening the oil cap. so i figured it was the pcv valve because it ventilates crankcase pressure. but after i changed the pcv valve and drove it till it warmed up it did the same thing. and the hiss comes from the oil cap and distick. i tried searching on here but could not find anything. has anyone had this problem? or does anyone know what the problem might be? i am afraid to drive my car for fear of catastrophic internal damage if its something bad.

 

anybody....? help please....

 

never heard it before.. bump for an answer for this guy.

 

make sure the PCV hose is not clogged with gunk , and that the intake manifold is providing proper vacumm. You can pop the PCV valve as the engine is running and put your finder on it to check if there's suction present. Also, check for excessive blow-by via a leakdown test, but that is highly unlikely if your engine has relatively low miles and it has been well maintained.

 

Is it a suction noise or a blow-ot noise? It'd make more sense if your rings were starting to let air out & you have a + gauge pressure in your crankcase (lots of blow by?). Are you sure the PCV you changed it to is good? (clicks when you shake it)?