So I have been offline for a while, but recently I noticed a high pitch "whistle" coming from what I think is the engine, inside the cabin. The whistle can be heard at 2000+ RPM and can be heard while moving and stopped. Here is the issue the sound cannot be heard on outside the vehicle.

I have managed to rule out stereo or climate control as factors, as I have tested with these turned on as well as turned off the and the sound is independent of these systems.

No I have very sensitive ears, and to me it sounds like it is some sort of electrical whine, however when the engine is off there is no whine, so yet again another dead end.

With these points in mind I believe that it could be one of two things.

1. Leak some where in the intake manifold/airbox system
2. Leak in vacuum system

The issues I also have with both of these is that I have not had any diminished or abnormal engine issues ever, which to me would almost completely rule out the vacuum leak.

I thought it might be an engine bearing, but then I would expect to hear some unsusual engine noises as well as the stereotypical "wur" of a bad bearing. Also the sound does not appear to be anymore noticeable at 4000 RPM then at 2000 RPM.

2008 LT2 2.4 18XXXXX KM
So yeah thoughts?

 

Some info like year and engine would help.

 

2008 2LT 2.4 18xxxxx KM dialed in

 

Flex pipe.

 

I concur, flex pipe

 

You've done well, nearly 2 million kilometers and still going strong!

 

lololol

 

See I thought this might be the case, however I checked and it has been replaced with an aftermarket one already.

 

That doesn't mean it didn't crack or a nut come loose and/or burn up the gasket.

The other thing could be the rubber cap on the t-stat housing can crack and leak at high pressure. It turns to steam so no visible dripping.

 

So how does one test for leaks in the flex pipe area?