Engine whistle after intake R & R

[vwnut]

I've been chasing a suspected vacuum leak for some time on a 1999 3ltr.
I removed the upper intake manifold thinking maybe the pcv hose was cracked and leaking.
The hose was ok. Now after replacing the intake it has developed a whistle/chirp when I bump the throttle quickly off idle.
It sound like it's coming from the rear of the engine towards the drivers side. Any thoughts?

 

[rusty ol ranger]

Spray some ether around where you mated the intake. See if the RPM's increase a bit.

Sounds like the intake didnt seal well.

 

[vwnut]

The idle remained the same after replacing the gasket.
Wouldn't the idle increase some if the gasket didn't seal?

 

[rusty ol ranger]

The idle remained the same after replacing the gasket.
Wouldn't the idle increase some if the gasket didn't seal?

Depends how bad the leak is.

Did you also remove the throttle body? Could be the gasket on that.

 

[vwnut]

Depends how bad the leak is.

Did you also remove the throttle body? Could be the gasket on that.

The throttle body stayed on. Just unplugged the sensors and flopped the manifold over to avoid draining off some coolant.
It seems to be quite a loud whistle/chirp to be a small leak.

 

[Curious Hound]

Are you sure it’s not the cam position sensor shaft squeaking? That would be more chirp than whistle. But, I haven’t heard your noise.

 

[rusty ol ranger]

The throttle body stayed on. Just unplugged the sensors and flopped the manifold over to avoid draining off some coolant.
It seems to be quite a loud whistle/chirp to be a small leak.

A smaller leak will usually whistle louder as the air is being sucked through a smaller hole

 

[stmitch]

Are you sure it’s not the cam position sensor shaft squeaking? That would be more chirp than whistle. But, I haven’t heard your noise.

Yep. Cam synchro is at the back of the intake and likes to chirp/squeal when it loses lubrication

 

[vwnut]

Are you sure it’s not the cam position sensor shaft squeaking? That would be more chirp than whistle. But, I haven’t heard your noise.

It had a new OE CPS less than 3000 miles ago

 

[SenorNoob]

Is it possible it's not leaking into the intake but out underneath? I know I misunderstood the directions with my first intake gasket. It said to put sealer in the corners. At least on the 4.0 it has to go all the way across the block surface.

 

[vwnut]

Is it possible it's not leaking into the intake but out underneath? I know I misunderstood the directions with my first intake gasket. It said to put sealer in the corners. At least on the 4.0 it has to go all the way across the block surface.

I didn't get into the lower intake gasket; just the upper.
Should have been pretty straight forward

 

[pjtoledo]

inspect that hard rubber hose under the intake to the PCV

 

[vwnut]

inspect that hard rubber hose under the intake to the PCV

That's how this all started.
I removed the manifold to check the hose for possible cracks/leaks.