Vehicle is a 2001 Discovery II SE7. With the engine running at non-idle speed, when I take my foot off the pedal, the engine whistles until it gets to idle speed and then the whistle stops. The whistle only occurs when the engine is decelerating down to idle. It does not make the sound when accelerating or at idle. The whistle occurs whether the car is in gear or in neutral. I've localizedthe soundto the engine compartment but nothing more specific yet. Any suggestions? This is my first post so please be kind ;-) Tom

 

I've noticed a similar sound, but only when I let off the gas at highway speed (above 65mph) and it only whistles for a brief second. I know the front driveshaft can make some weird noises when it's about to go out, but I just had mine rebuilt and it didn't affect the noise one way or another. I'd be curious to know what it is.

 

If you believe its isolated to engine compartment, one of the first things I would check is the drive belt accessories and tensioners. A bad tensioner can howl or have a high pitched noise when they start to go south. In my experience with BMWs only when really worn do they make alot of noise at idle.

Good luck

Greg

 

As a follow-up for the benefit of others who have this problem, the cause was a leaking lower intake manifold gasket (ERR7306). Lots of work to get at it but that's what did it.

 

Thanks for the follow up.

 

So take this opportunity to replace your plug wires while the manifold is off. A goo set of Magnacor 8mm wires will bring your engine back to life.

 

You read my mind! I did indeed install a new set of Magnacor wires during the reassembly.