GM 3.4 or 3.5 v6 oil fill cap with vent

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Jun 7, 2014
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MI
Okay so I noitced that my wife's G6 3.5 engine , and some other gm 60 degree v6 engines have a spring loaded valve built in to the oil fill cap. I checked on the 3.8 v6 in some other gm cars at parts galore and they do not have that same type of cap. Can some one explain to me the purpose and how they work please ? Thank's
 

Highwaymiles

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Joined
Jun 7, 2014
Messages
7
Location
MI
I opened one up and found a small spring and rubber diaphragm. It might not be vented but some kind of a pressure relief valve ?
 

Highwaymiles

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Joined
Jun 7, 2014
Messages
7
Location
MI
ACDELCO Part # FC219 More Info {#12573342, 12589430, FC205} GM Original Equipment SAE 5W30, VENTED, W/SEAL
 
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