SOLVED!: E53 X5 3.0 sounds like dying banshee on fire when I take my foot of the gas

[cn90]

1+,

- My guess is the belt system, probably some dry pulley bearings...

- Search forum for "Partial cooling overhaul" I wrote a few yrs ago...

[IkirisTheX5]

Thanks for the suggestions guys. Maybe I should revisit those components. I sort of brushed off belts and pulleys after both my indy mechanics threw that notion out the window first. I never second guessed them because the causalities that contribute to the squeal don’t seem belt related. For instance what does me letting my foot off the gas have to do with a high pitch squeal/whistle coming from the engine only when it’s hot… My mind has always been on the intake system because what’s the one thing that closes when you no longer accelerate (take your foot off the gas), air and fuel to the engine, right? Besides so much of the intake is plastic it made sense for something to start whistling only once the engine warmed up and expanded something.

I’ll post a video of the sound in just a sec. maybe one of you guys will recognize it, coz I sure haven’t been able to.

[Fifty150hs]

Originally Posted by cn90

1+,

- My guess is the belt system, probably some dry pulley bearings...

- Search forum for "Partial cooling overhaul" I wrote a few yrs ago...

+2

Sounds like bearings for the idler and tensioner pullies. Had a similar issue several years ago. Used a stethoscope to pin it down. Replaced the pullies and no more noise.

[IkirisTheX5]

Originally Posted by Fifty150hs

+2

Sounds like bearings for the idler and tensioner pullies. Had a similar issue several years ago. Used a stethoscope to pin it down. Replaced the pullies and no more noise.

@Fifty150hs: thanks so much for sharing - that's a great start to my hierarchy list of most likely bearing components to fail in the M54.

You think I should go for a full accessory drive belt kit like the one in the link and knock out all potential problem areas along the belt route?

https://www.fcpeuro.com/products/bmw...iABEgKL8vD_BwE

[Fifty150hs]

Originally Posted by IkirisTheX5

@Fifty150hs: thanks so much for sharing - that's a great start to my hierarchy list of most likely bearing components to fail in the M54.

You think I should go for a full accessory drive belt kit like the one in the link and knock out all potential problem areas along the belt route?

https://www.fcpeuro.com/products/bmw...iABEgKL8vD_BwE

What year is your X? That may not be the right tensioners. I have an '06 and it has the "hydraulic" tensioner. That said, if you can't hear those bearings with your stethoscope, putting those parts in will likely cure your problem if those parts have bad bearings. My X didn't really make much noise at idle either, but with the stethoscope, using the little cone ended attachment, I could here a little bit of bearing noise in my pullies. That's why I went ahead an replaced them.

This is the tensioner my X has: https://www.fcpeuro.com/products/bmw...1287838797-1-2