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

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

Get a Harbor Freight stethoscope and check everything being driven by a fan belt.
It could be early bearing failure in any one of a number of accessory and idler pulley components. You can also pressurize various vacuum hoses to a couple psi separately and specifically with a regulator and blow gun with tapered rubber nozzles also from Harbor Freight. This is just a bit different than the smoke test but more of a Hiss test. Some internals of various vacuum devices could be failing and you wouldn't see it via a smoke test.

1+,

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

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

Belts and pullies, really?
 

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. :dunno:

Here is a link to the VIDEO of the sound in question. To refresh, only appears after roughly 30 mins of driving in hot conditions and ONLY when I remove my foot of the gas and coast, then louder when I apply the brakes; disappears immediately when either gas is applied or car comes to a complete stop: https://youtube.com/shorts/GouqH96gN4o?feature=share

https://youtube.com/shorts/GouqH96gN4o?feature=share

https://youtube.com/shorts/GouqH96gN4o?feature=share

(Sorry not sure yet how attachments work on this forum)

EDIT: Now with more video :popcorn:!

https://youtu.be/-blBjHFya0A

take your belt off and run the engine after it’s warmed up of course. Definitely sounds like a bearing situation and I have worked on a car where the tensioner wore out and was angled a little bit I was actually able to repair it by cutting a counter angle in the mount.

That’s sad day when it warms up factor hints at a problem with the fan clutch. You can again wait for it to warm up pop off the fan And see if the sound goes away.

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.

did you drive thru the New Mexico desert?
 

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

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. :D :bustingup. 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. :rofl:

+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.