# X5 diesel engine noise. Please help diagnose. (Vid inside)



## Dr. Anthony (Oct 12, 2015)

Hi guys, I have been lurking a lot lately, but finally decided to register.

I have a 2009 X5 diesel and I'm trying to diagnose a noise. It sounds like a screeching.. loud scream. I've posted a video and was wondering if someone has heard this before. I've been searching all week and have yet to find something similar. Sorry for the poor quality video, but it's all I could come up with.

any help is greatly appreciated.
the engine light is related to nox sensor replacement.
currently have 210,000 km (130k miles)

https://www.youtube.com/watch?v=PclB_FxEEPM_a_

****update*****
Alright, so I thought I would give an update to my issue. Long story short, its not solved yet. But here's what we did do.

Did a smoke test. Everything was good, except... where the wastegate is on the lower turbo. That's where you can see some soot escaping.. So the wastegate bushings/seals are gone.. and Looks like i'll need to pull the turbo off to get it rebuilt or swapped out.

I feel a bit of play. if I hold it closed, the noise goes away. Obviously I don't want to do this long term. I just wanted to see if I could replicate the noise while holding pressure on the wastegate so it doesn't move. Noise could NOT be replicated.

I also scanned for codes with a different machine and was able to get a few more out of it. I'll update the 1st post to show these for others searching.

they are:

4BB3: Nox sensor before denox cat- plausibility nox
4b6a: Nox sensor before denox cat - Plausibility
46B4: NOX Sensor before denox cat plausability nox.
4C04 - I think this could be EGT temp is too high (non-plausible)
4D16 - SCR system, efficiency: Efficiency too low
46A4 - NOx sensor after DeNOx cat., plausibility NOx: NOx signal offset too high at trailing throttle


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## Flyingman (Sep 13, 2009)

Dr. Anthony,

I assume these all occurred while you were idle (i.e. not actually driving the car)!:rofl:

The first thing that comes to mind is fan belt and perhaps one of the various pulleys, idlers, that run with the fan belt. Perhaps it is just loose or you are about to loose a pulley bearing?

Alternator, power steering, water pump is another possibility.

It didn't screech like the infamous fan belt we had early on. That you could hear a mile away!:thumbup:


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## Dr. Anthony (Oct 12, 2015)

Flyingman said:


> Dr. Anthony,
> 
> I assume these all occurred while you were idle (i.e. not actually driving the car)!:rofl:
> 
> ...


The first part of the vid, I was driving.. the 2nd part (underhood) is sitting stationary. Aside from the noise, it drives normal. I'm hoping its just an accessory, or a pulley. What i found was that it doesn't sound like its affected by RPM tho. It feels to come out more with load. (which is why it was hard to get it on vid while in park)

I'm going to say it doesn't sound like a belt issue. I'd know what that sounds like 

1 thing i'm going to try is to remove the accessory belt and see if I can hear it.

I can't even find other videos to compare sounds. to me, it sounds bearing related.. but then again, I'm just taking guesses.

I'm fairly mechanically inclined so I'd love to deal with this myself.


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## KeithS (Dec 30, 2001)

I'd take a stab that it may be a belt idler pulley. You have enough miles for it to happen. Pulling the belt will indicate this real fast. Remember no belt = no water pump.


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## Dr. Anthony (Oct 12, 2015)

KeithS said:


> I'd take a stab that it may be a belt idler pulley. You have enough miles for it to happen. Pulling the belt will indicate this real fast. Remember no belt = no water pump.


Hmm, I would think it would be constant, regardless of load tho wouldn't it? Either way, I'm going to try to remove the belt today see if it goes away. IF that's all it is, I'll be pretty happy


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## Flyingman (Sep 13, 2009)

As we are armchair diagnosing, another possibility could be a turbo leak or charge air leak. One of the hoses. Recall we have gates that open and close at various loads to spool up the smaller and larger turbo, plus the waste gate.:dunno:

Our cars have electric radiator cooling fans but some cars are belt driven and have a type of clutch on them so the fan doesn't over speed with engine rpm, a type of slip clutch. That could make a weird noise depending on load, but not applicable to the BMW.

I can see a shop visit in your future.

It the recording when you are under the hood, that is definitely a type of screeching sound, and seems to occur as you back off the throttle. Not a tranny issue. I still suspect one of your pulleys is about to go.


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## ard (Jul 1, 2009)

and I'll point out the CEL is on as well.


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## Flyingman (Sep 13, 2009)

Dr. Anthony said:


> Hmm, I would think it would be constant, regardless of load tho wouldn't it? Either way, I'm going to try to remove the belt today see if it goes away. IF that's all it is, I'll be pretty happy


Any resolution?:dunno:


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## Dr. Anthony (Oct 12, 2015)

Sorry for the lack of updates. I haven't bothered removing the belt yet. I have a feeling its boost/vac related. I'm going to smoke the motor and look for any leaks.
I did notice my boost pipe feels loose (the plastic charge pipe that goes into the EGR/throttle area) its all sooty too. I'm sure there shouldn't be any play in it, but I haven't taken it off to see how its designed to work. I jst noticed that today when I had a quick look.


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## Flyingman (Sep 13, 2009)

Dr. Anthony said:


> Sorry for the lack of updates. I haven't bothered removing the belt yet. I have a feeling its boost/vac related. I'm going to smoke the motor and look for any leaks.
> I did notice my boost pipe feels loose (the plastic charge pipe that goes into the EGR/throttle area) its all sooty too. I'm sure there shouldn't be any play in it, but I haven't taken it off to see how its designed to work. I jst noticed that today when I had a quick look.


There has been a few posts on leaking boost hoses and seals. Even some how to videos on you tube.


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## Dr. Anthony (Oct 12, 2015)

Flyingman said:


> There has been a few posts on leaking boost hoses and seals. Even some how to videos on you tube.


Thanks! 
I don't suppose you have any of those links do you? I tried searching for similar videos earlier and came up dry.


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## Flyingman (Sep 13, 2009)

Give this a try:

http://www.bimmerfest.com/forums/showthread.php?t=753755&highlight=leaking+charge+hose


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## Dr. Anthony (Oct 12, 2015)

Flyingman said:


> Give this a try:
> 
> http://www.bimmerfest.com/forums/showthread.php?t=753755&highlight=leaking+charge+hose


Excellent! Thank you

*edit* 
When I emailed that company, they said the pipe doesn't fit the X5, and its for the 335d only.


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## Dr. Anthony (Oct 12, 2015)

Alright, so I thought I would give an update to my issue. Long story short, its not solved yet. But here's what we did do.


Did a smoke test. Everything was good, except... where the wastegate is on the lower turbo. That's where you can see some soot escaping.. So the wastegate bushings/seals are gone.. and Looks like i'll need to pull the turbo off to get it rebuilt or swapped out.

I feel a bit of play. if I hold it closed, the noise goes away. Obviously I don't want to do this long term. I just wanted to see if I could replicate the noise while holding pressure on the wastegate so it doesn't move. Noise could NOT be replicated.

I also scanned for codes with a different machine and was able to get a few more out of it. I'll update the 1st post to show these for others searching.

they are:


4BB3: Nox sensor before denox cat- plausibility nox
4b6a: Nox sensor before denox cat - Plausibility
46B4: NOX Sensor before denox cat plausability nox.
4C04 - I think this could be EGT temp is too high (non-plausible)
4D16 - SCR system, efficiency: Efficiency too low
46A4 - NOx sensor after DeNOx cat., plausibility NOx: NOx signal offset too high at trailing throttle


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## beemerman347 (Nov 6, 2015)

Dr. Anthony... With the related codes you have stored in the dme all sensors ain't reading as supposed to under acceleration, the engine should lagg at about. 3500 o 4500 rpm rev. As to my findings.. Diesels are great your body and year, rallye bmw has very good techs onto finding your issue, but besides the codes and check eng. Light being on, your mostly concern the noise which can be caused by boost blockage


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