Strange intake noise?

[chaseincats]

30 minutes ago, Zed Head said:

I watched the video and don't hear the noise.

Are all of the various vacuum ports on the intake manifold used or sealed?  Charcoal canister, AC system control, brake booster, etc.

You hear it especially well when I put the camera right next to the air cleaner. It’s a loud sucking noise much louder than my car.  You literally can hear it coming down the street it’s really strange.

[Zed Head]

Put the factory air cleaner back on and see if it's still there.  Automotive engineers spend a lot of time figuring out how to quiet intake noise.  

People pay good money for "cold air intakes" to get that noise.

[Patcon]

Take a legth of hose and use it like a stethoscope, move it around and see if you can pin point the noise. You may here it good at the intake opening but see if you can here it somewhere else.  Like around the manifold or injectors

[chaseincats]

22 minutes ago, Zed Head said:

Put the factory air cleaner back on and see if it's still there.  Automotive engineers spend a lot of time figuring out how to quiet intake noise.  

People pay good money for "cold air intakes" to get that noise.

The problem is the noise is there with the cold air intake removed.  It's also there with the afm removed haha.

[chaseincats]

5 minutes ago, Patcon said:

Take a legth of hose and use it like a stethoscope, move it around and see if you can pin point the noise. You may here it good at the intake opening but see if you can here it somewhere else.  Like around the manifold or injectors

The sound literally comes through the intake piping all the way to the throttlebody

[Zed Head]

You got my point backward.  The "CAI" lets the noise out.  The factory air filter keeps the noise in.  It's just normal air flow noise.

[chaseincats]

12 minutes ago, Zed Head said:

You got my point backward.  The "CAI" lets the noise out.  The factory air filter keeps the noise in.  It's just normal air flow noise.

The strange thing is my 78 has the exact same air filter and doesn't make that sound the only difference is I have the weber big-throat throttlebody

I believe he has the stock air cleaner so I'll pass the message along to give that a shot though

Edited August 14, 2022 by chaseincats

[Racer X]

Double check that the PCV valve isn't stuck open and letting in excessive air.

[chaseincats]

Update for you guys.  The PCV valve even though its a few weeks old very much is letting air in both directions not to mention the pcv hose is apparently split towards the top.  He's going to get a replacement valve and snip off the torn portion of the hose.

When I hear how it went I'll update you all.  Thanks so far

[chaseincats]

I spoke with him and he bought a brand new valve but said he could blow through both sides there too.  He read later on that blowing into these doesn't tell you anything, you have to suck on it to get an actual answer of if its bad or not - is that correct?

[Zed Head]

[Zed Head]

13 hours ago, chaseincats said:

not to mention the pcv hose is apparently split towards the top.

This is the most likely cause of the noise.  The system is not "intact".  During normal operation of an engine with normal blowby there won't be very much flow through the valve.  Just enough to clear out the gases.

Edited August 15, 2022 by Zed Head
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