"wooshing" sound / lifters
 

Figured I'd start a new thread for this one...

Here's a quick vid I took while I had the engine cover off:
http://www.youtube.com/watch?v=yNPudQRyWAo

What the hell is that slower "whooshing" sound? It's hard to hear the lifters in that video so I might try to get a better one.

I've never been around another boxster that had the engine cover off so I don't know what I'm hearing or what's normal.

EDIT: for what it's worth, this vid was taken immediately following an oil change.

Maybe the serpentine belt? It sounds rhythmical but with a long interval.

What kind of shape is your AOS in? That kind of sound complaint is common with an AOS on the way out.

Tagging on JFP's thoughts, remove the oil fill cap while the engine is running, what happens? Does the engine idle (RPM) drop or increase?

Jager

hmm i'll check the oil fill cap.

AOS just replaced about 2k miles ago.

car runs like 'poo' with the cap off.. surges and hunts for idle (doesn't sound like it will die, but surges pretty low). I'll have a video in a few minutes.

the AOS recommendation sounds disappointing as I just had it replaced not too long ago. I do have an exhaust leak that I haven't pin-pointed yet though, not sure it they're related.

Is there a way to perform a "vacuum leak" test somehow, or something similar to smoking the exhaust to get a visual of the leak?

after swapping the MAF, no CEL's for 600+ miles.

Yep, that is an indication of a bad AOS, my experience. With a new/good AOS the idle should go up a little when you remove the oil fill cap.

How much oil are you putting into the crankcase? I have made the mistake of putting too much oil in the motor and believe (just a theory) that's what caused my AOS failures in the past. I'm now keeping the oil level between the high and low indicator marks on both the dip stick and dash display. So far no AOS issues (knock on wood).

Jager

Just to expand on removing the oil fill cap test... Make sure the engine is up to temp (~180 degrees) when you remove the cap. The idle should be ~700 RPM and when you remove the oil fill cap, the engine will lope a little but the RPM's should stay the same or increase a little. If the engine idle drops, and it sounds like it is going to die, most likely bad AOS.

Jager

here's the video: http://www.youtube.com/watch?v=4UYw4x_VHPI

it's kinda hard to hear with the wind (sorry), but you can hear the engine "normalize" after putting the cap back on the second time.

I honestly don't know if the rpm's were jumping as I didn't look at the gauges when I did it, but it sounded like it was surging..

a failing AOS usually throws smoke at startup, mine doesn't. My cold starts are rock solid and it idles perfectly. Runs fine even on hot starts.

vacuum leak maybe?

It's hard to tell what's going on with the video audio. Was the engine warmed-up when you performed the test? The car will almost stall/die when the AOS diaphragm is bad and you open the oil fill cap.

Hopefully you don't have a bad AOS, maybe the sound you are hearing is just air flow through the throttle body??

Jager

i'm pretty confident the AOS is good. is that "sucking" sound "normal" when removing the oil cap? I can't remember if the car was up to temp. I know it wasn't completely cold, but definitely not up to temp (180ish).

when I'm in the driver's seat, it sounds like it's more towards the passenger side of the engine compartment. of course, everything sounds like it's coming from the wrong place when you're inside the car.

Yes, there is a lot of vacuum/suction when you open the oil fill cap, but it will sound like a shop vac when you have a bad AOS.