Dadddio

Got a bad whistle somewhere in the intake.
I pulled the intake to put in Greg Browns oil baffle.
When I put everything back together i have this whistle.
Took it apart again, pressure tested the TB.
The throttle body O-rings were leaking, I replaced them.
Put it back together.....still whistling.
Sounds like it is coming from my ISV.
It is new.....anyone have this problem?
Solution?......Ideas?

joejoe

Jeeees louise, have no idea but sounds terrible.

Jchiodi

There are so many places that that intake could suck air it's not possible to list them all!

I would however try squirting a touch of starting fluid around the hoses and clamps for starters... just enough to see if you get a response from engine? Should eventually find it!

The Forgotten On

Try puffing a cigar's smoke into the intake while the engine is off to find leaks. It's a fair bit safer than using ether on a running engine.

But geez, I have never heard a squealing leak that bad before.

SMTCapeCod

You don't have a flappy [valve] in the [S4] way that term is usually applied. I think you mean the throttle body?

Frequent fliers for the intake whistle are the Idle stabilizer valve/associated hose. Given the service, the vent tube on the water neck is a good prospect.

https://rennlist.com/forums/928-foru...e-whistle.html


Mechanics stethascope may help you isolate, and/or the smoke.

EDIT: Ok, now that I've heard the vid...wow, that sounds almost like a reed valve, I'm a little concerned that something may have been left in the intake track? Maybe a collapsed hose....What came off for the baffle R&R?

MarkRobinson

I recently had a very bad whistle after rebuilding a motor with a powdercoated intake: one of the runner flanges was no longer flat (was a donor intake) and had to be placed on a flat surface with lighting to see how non-flat it was. A few passes on a belt sander fixed it just fine.

Yes, use a firework punk, incense stick, or cigar to find the source of air infiltration.

WallyP

Get a four-foot piece of rubber or plastic tube, stick one end in your best ear, and use the other end to locate the leak.

MarkRobinson

I used a stethescope to narrow my search, but the smoke verified it precisely.

Dadddio

Capecod,
Stripped the entire intake plus water bridge.
So, pretty much everything.
Gonna have some better ears listen tonight.
Gonna see if it changes with idle adjustment also.

Indy Rev

Sounds like air moving across a reed. Is there any part of the intake that would have a thin gasket?

Dadddio

Crap.
Now that you mention that, it does.
Like blowing across a piece if plastic or rubber or silicone.
I have silicone intake gaskets.....not sure that's what it is, but it sure does sound like it.
I guess I need to put paper gaskets on trim the silicone ones.
What do you guys think?

Indy Rev

Hope its that simple
My other thought was a stuck leaf, but eventually it would break and get sucked in.

Dadddio

Okay.
Removed the intake and throttle body.
Removed all hoses, re-installed.
Trimmed a few edges on the silicone gaskets.(don't think that was the problem)
Put it back together.....still whistling.
Never did this before.
The only thing different is the oil baffle.
Listened with a piece of hose, sounds like it's
coming from the front of the throttle body.
Guess i need to do a smoke test next.

928autobahndreamer

I had the exact same thing happen when I redid the top end of my 87. I dissasembled and reassembled and the whistle continued. Once I went through a few heat cycles, the whistle stopped. The only thing I could figure was that some of the the paper gaskets had a glue bead that did not go all the way around. Once the engine heated and the glue melted the gasket sealed better. It has been a few years. Let me see if I can find the thread.

928autobahndreamer

I bumped my old intake thread to show the post about the whistle. It is on post 80.