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

[PalmSpringsE534.6]

Originally Posted by IkirisTheX5

Hi fellow X’ers,

Although been reading and learning from Xoutpost the last couple of years since I adopted my beloved rescue 2002 X5 3.0 (that’s taken me from Texas to NYC to LA and back, and spent several nights at the Salton Sea, in Death Valley and the Badlands having never let me down), this my first official rookie post. So apologies for any gaffs, but I need help, serious HELP!

As of about 90 days, every time I drive the X5 for more than 30 mins straight a higher pitch squealing or whistling begins screeching out of the engine bay everytime I simply release my foot of the gas, and gets louder when I apply the breaks - then - like magic the ear-piercing screech instantly disappears when the truck comes to a full stop or I give it a little bit of gas. It’s so loud it literally sends people begging for change at interjections running off in pain, with ears covered.

Myself and two Indy mechanics I trust and respect have given up on her. So far we’ve changed:

- the valve cover
- the 90° rubber intake elbow boot
- the air filter unit including resonator box
- the DISA valve
- the brake booster
- have performed the smoke test on vacuum lines to no avail
- I sprayed a can of carb cleaner in/around all intake components to detect a breech of some sort - nothing

I don’t know what to do next and I can’t imagine the dealer-stealer can’t help anymore than what I’ve done at this point.

PLEASE PLEASE has anyone ever resolved this in their own vehicle or have any idea what I could check or replace next?

Xoxo

You have no idea how lucky you are! You got the E53 Banshee prototype! There was only ONE made...you lucky devil.

[IkirisTheX5]

Originally Posted by PalmSpringsE534.6

You have no idea how lucky you are! You got the E53 Banshee prototype! There was only ONE made...you lucky devil.

Well, PalmSpringsE534.6, since it seems you truly grasp the value of such a rare piece of German engineering, I’m happy to trade my Bavarian Banshee edition X5 for pretty much any flavor X5 you can find that is in as good or better daily driver condition as mine.

[IkirisTheX5]

[QUOTE=andrewwynn;1207344]take your belt off and run the engine after it’s warmed up of course.

That's a pretty ingenious diagnostic hack... I think I would need to be able to drive it at minimum 20 mins even if I take the belt off warm to convince myself the noise is/isn't there. Will an 18 year old X5 run for 20 mins in triple digit Texas summer heat w/ no belt?

[IkirisTheX5]

@ahlem: When I go tomorrow to pick up my Harbor Freight stethoscope, what exactly will I be listening for? The car, no matter how long it idles or was driven beforehand, will simply not make the banshee scream at any RPM while stationary. Is there a tell tale sound I could pick up on in the stethoscope to alert me to faulty bearings?

[IkirisTheX5]

Originally Posted by X5chemist

Wow, that's loud! If the idle pulley and belt tensioner have over 20k miles, I would replace them. Same for the A/C pulley.

For giggles, does the secondary air injection pump turn on? At first start up on mine, it does. I replaced mine. It sounded like a jet taking off. The screeching is ear piercing.

Next, lift each front wheel separately and turn the wheels. Keep eliminating easy stuff first.

Great coast to coast runs! And back to TEXAS! I want to spend time fixing mine up for long trip runs. Sporty, fun size, and decent mileage.

X5Chemist: I haven't considered the secondary air pump... how would I know whether it's working properly? Upon first turning over and idling (hot or cold) there is no trace of this vile sound, but if it were the pump it could be possible it doesn't turn on until the engine is good and warm I suppose so probably worth checking (once I learn how).

Yes, do trek across N. America in your X5, especially spending time in landscapes suitable for "overlanding". Mine did exceptionally well crossing wild terrain (areas in the Mojave and Great Salt patch especially) and it's worth every cynical glance you'll get each time you pass a 4X4 driver w/ a 20" lift kit struggling to keep up.

[IkirisTheX5]

Originally Posted by workingonit

Sounded very familiar to me: https://youtu.be/KPw4U_IhWV4

@Workingonit: Hahaha, that sound is spot on!

And, yes, spent a lot of time in NM - White Sands, Truth or Consequences, the Trinity site, Roswell, Santa Fe, Albuquerque, you name it - probably my 2nd favorite state in the US; gorgeous roadtrip landscapes.

[IkirisTheX5]

Originally Posted by oldskewel

Bearings can make sounds like that, that come and go very abruptly. The instant on / off is an important clue here. Foot off the gas would let the engine spin down, changing the drive belt tension, which might trigger an alignment shift in a worn, dry bearing, that might turn the sound on instantly.

Is there any way you can recreate the sound while it is parked? If not, that's an important clue too. And it will be tougher to diagnose.

Sounds in general can be really tough to trace. Has the problem progressed to the point where it is exactly predictable when it will occur, and if so, what is the easiest way to get it into that state? For example, easiest would be if you need to drive for 30 minutes, then park it, pop the hood, and rev and let off the engine.

Belt off is a great way to quickly rule a bunch of stuff in or out if you are able to conduct that test. Belt runs the water pump, so you won't be able to drive it 30 minutes, for example. PS too, so don't count on making sharp turns. With no alternator spinning, the battery will be lucky to last 30 minutes. Everything will do fine in park though, for a few minutes.

Have you tried shifting to neutral while it's happening? Shifting gears manually?

Is it definitely coming from the front / engine / front differential area?

And on the "whistling" - I once had a bearing failure that sounded like that - I would have sworn there was gas or liquid involved, but it was a worn bearing (fan bearing on an old Lexus).

Another time, there was a high pitched whistling that would only occur when going over 80 mph and maintaining speed (neither accelerating nor coasting), and it would go away instantly when I'd slightly roll down a window, trying to hear better. I was convinced it was some aerodynamic / air pressure effect. That turned out to be the automatic transmission. . Gave up trying to figure it out, and then we noticed it went away after the AT was replaced. LOL, so now you know why I'm so cautious about believing things.

@Oldskewel: thanks for the thoughtful reply. you definitely answered some of my questions on the dangers of the "belt off"diagnostic approach. I can predict with almost certain accuracy when the noise will begin (+/- 5 mins) and the shit of it is I've never been able to recreate it while stationary. What everyone has suggested about the bearing culprit is really convincing. I may do some research and create a hierarchy of bearing driven components in the M54 engine based on likelihood of failure and just start replacing them one by one.

[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

[oldskewel]

Too bad it won't happen when in Park. And that is an important clue. It does point away from anything related to the drive belt, but I'd still consider that.

So I doubt the stethoscope will be useful.

Some tests you can still try:
- remove any of the optional plastic panels in the intake area. You'll be taking them off anyway, and just in case there is some aerodynamic whistling due to those you will rule that out when the problem appears.

- get the problem happening.
-- Go in to manual mode and see if that has any effect, while staying at about the same speed. Changing gears at the same speed will change engine RPM. Any change in the noise would narrow it down. For example, maybe it only happens in 5th gear, which would be a good clue.
-- vary speed and see if it changes, while in the same gear
-- shift into Neutral and see if it changes
-- gradual left turn vs. gradual right turn, while maintaining speed (will of course need to find road to cooperate)
-- accelerating vs. coasting vs. light braking

On the drive belt bearings ...
Figuring you'll be putting stuff off and on, you should set as much stuff aside as you can until the problem is solved. E.g., the fan shroud, but make sure any loose wires cannot contact the fan.
You can take the AC belt off and leave it off, just in case the problem is in the AC or the AC tensioner pulley. Test like that.
Similarly, can try with the engine fan removed.

Once you get to the pulleys, with the drive belt off, you can feel them for smoothness and wobble, while they are still installed. Ideally, you will find one of them that feels really loose and maybe even rattling. If not, it is a tough call on whether to just replace everything. Different people have different philosophies about when to bring out the parts cannon.