Vacuum when Oil Cap Removed or Not ?

raffi007 · 02-12-2020, 10:07 AM

Hi guys

I need some info concerning this matter.
I have a 335xi 2009 with the N54 engine.
I read alot of contradicting info concerning Vacuum at the Oil Cap

Some places i read there should be Vacuum when the oil cap is opened while the engine is running and idle should change.

and other places i read that there should not be any vacuum.

I have an oil catch can installed and a new upgraded PCV valve

Thank you

WoodE30 · 02-12-2020, 10:28 AM

If everything is good, no vacuum leaks, our cars have very little engine crankcase vacuum. If you open the oil cap with engine running and it feels like there's vacuum present it's more in likely your crankcase vent valve.

The specific measurement for N54 is 17 mBar.

02-12-2020, 10:07 AM	#1
raffi007 Enlisted Member 3 Rep 31 Posts Drives: BMW 335i X-Drive Join Date: Apr 2012 Location: Lebanon iTrader: (0)	Vacuum when Oil Cap Removed or Not ? Hi guys I need some info concerning this matter. I have a 335xi 2009 with the N54 engine. I read alot of contradicting info concerning Vacuum at the Oil Cap Some places i read there should be Vacuum when the oil cap is opened while the engine is running and idle should change. and other places i read that there should not be any vacuum. I have an oil catch can installed and a new upgraded PCV valve Thank you
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02-12-2020, 10:28 AM	#2
WoodE30 Capt. Maverick 62 Rep 295 Posts Drives: 89 E30 325is, E92 335i N54 Join Date: May 2018 Location: Los Angeles iTrader: (0) Garage List 2013 X5 3.5xdrive [0.00] 1989 325is [0.00] 2008 335I coupe [0.00]	If everything is good, no vacuum leaks, our cars have very little engine crankcase vacuum. If you open the oil cap with engine running and it feels like there's vacuum present it's more in likely your crankcase vent valve. The specific measurement for N54 is 17 mBar. Last edited by WoodE30; 02-12-2020 at 11:03 AM..
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