random engine noise

Cornfedgt · Oct 12, 2012

I replaced the PCV valve on my mustang after I discovered it was shot. Well about three weeks later the noise came back and sounds like pressurized air being released but the strange part is, is the noise only happens after the car gets turned off. Any of you guys know what that could be. It even stumped a ASE certified mechanic lol.

MustangChris · Oct 12, 2012

Front or rear main seals. Is it leaking oil?

Sound coming from the front of the engine?

BigBore96 · Oct 12, 2012

So it sounds like you have air being let go when you shut your car off? Any ill effects you have noticed? Do you have a cold air intake? Couple of my cars have a noticeable almost blow off sound with their cold air kits.

Check the IAC lines and make sure they are tight. Common for IAC to make noise when going bad although generally they sound like a goose.

Can you narrow down where the noise comes from? A friend should be able to start/shut off the car and help you hunt it down.

Cornfedgt · Oct 12, 2012

MustangChris said:
Front or rear main seals. Is it leaking oil?

Sound coming from the front of the engine?

Nothing is leaking from anywhere. The noise sounds like its coming from the front passenger side. I'm not entirely sure if I missed a step when I installed the new one.

Cornfedgt · Oct 12, 2012

BigBore96 said:
So it sounds like you have air being let go when you shut your car off? Any ill effects you have noticed? Do you have a cold air intake? Couple of my cars have a noticeable almost blow off sound with their cold air kits.

Check the IAC lines and make sure they are tight.

Can you narrow down where the noise comes from? A friend should be able to start/shut off the car and help you hunt it down.

Yes I do have a CAI. I have checked and double checked the lines and when I first noticed the sound I had my buddy do exactly that, but now that you mention it it did start after I got the CAI.

BigBore96 · Oct 12, 2012

It's probably just the CAI. My car does it. It does it even more now that I added a accufab oval TB to the mix. It whistles like a mofo now all the time.

2lowsn · Oct 12, 2012

^this

Cornfedgt · Oct 12, 2012

Sweet thanks guys

FrankenStang · Oct 12, 2012

my 32v also does that when i shut it off, i hear it coming from the inatke tube like its getting rid of excess air...my other modded 4.6 did it also..

96greenvert · Oct 22, 2012

check the rubber seal from your airbox the large rubber peice thar extends into your fenderwell. sometimes will come off partially and allow excess air flow that you wont notice until you shut off car.

Cornfedgt · Oct 23, 2012

Ill do that wednesday greenvert. Its on jack stands right now as I am in the process of putting in an o/r x-pipe and all I need is my O2 sensors and MIL eliminator.

96greenvert · Oct 23, 2012

I think with your exhaust mods your doing it will sound so beasty you hear the air leak anymore.

BigBore96 · Oct 23, 2012

96greenvert said:
check the rubber seal from your airbox the large rubber peice thar extends into your fenderwell. sometimes will come off partially and allow excess air flow that you wont notice until you shut off car.

This does not apply with a CAI. That rubber piece you speak of it the stock silencer. Which is why when you install a CAI you hear the noise, which is completely normal