Oil Cap Air Sucking Noise

[Boxtaboy]

Huh?! There's supposed to be a suction noise? I thought it was supposed to be a complete seal? Ok, now you guys are gonna make me open my trunk while the car is running to check if there's any noise near the oil cap. LOL.

[dja1980]

Originally Posted by Boxtaboy

Huh?! There's supposed to be a suction noise? I thought it was supposed to be a complete seal? Ok, now you guys are gonna make me open my trunk while the car is running to check if there's any noise near the oil cap. LOL.

Actually, please do... lol

I would really like to get a concrete answer on this!

[Boxtaboy]

Originally Posted by dja1980

Actually, please do... lol

I would really like to get a concrete answer on this!

Haha...ok, no prob. When I go home later today after work, I will listen for any noise, and report back!

[ARModen]

I don't believe there should be air getting into your oil reservoir through the oil cap. The idea of the AOS is to separate gases in your crankcase from the oil and vent them back to your engine to be burned. This reduces emissions and increases power by maintaining your crankcase at a negative pressure. Excessive air coming through the cap, into the case, and into the intake manifold through the AOS, after the MAF, will cause your engine to run with an improper fuel/air mix. This will result in the CEL caused by error codes from the O2 sensors and/or MAF.

This is fairly trivial, and the DME is a little over sensitive to emissions issues.

If the AOS starts to fail then the gas from the crank will entrain oil into the engine causing the engine to smoke. (And ruin O2 sensors, which of course leads to CEL)

If it's air/gas coming out of the oil cap that's bad. Either the AOS is clogged (not real bad), which will produce a slight positive pressure in the crankcase, or you have some serious ring blow by. (bad)

[Boxtaboy]

Ok, just drove home, and then opened my trunk while engine still on, and took a listen. Absolutely no hissing noise from the oil cap area that I could detect. My oil cap is on tight. I did hear a little gurgling noise from the coolant tank though.

[S3adrag0n]

Ok, just drove home, and then opened my trunk while engine still on, and took a listen. Absolutely no hissing noise from the oil cap area that I could detect. My oil cap is on tight. I did hear a little gurgling noise from the coolant tank though.

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With the oil cap off or on? Mine is sucking air only with cap off; has no CEL or smoke and drives fine. I am a bit confused myself. I hear should not be sucking air and I also hear sucking air is OK with cap off.

[Boxtaboy]

Originally Posted by S3adrag0n

Ok, just drove home, and then opened my trunk while engine still on, and took a listen. Absolutely no hissing noise from the oil cap area that I could detect. My oil cap is on tight. I did hear a little gurgling noise from the coolant tank though.

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With the oil cap off or on? Mine is sucking air only with cap off; has no CEL or smoke and drives fine. I am a bit confused myself. I hear should not be sucking air and I also hear sucking air is OK with cap off.

As my post stated, "my oil cap is on tight."