Annoying whistle at 2K RPM

[garfield81]

This is in regards to a 2006 3.0i X5 with approx 70K miles. I have been noticing an annoying whistle at about 2K RPM. I have tried to reproduce the whistle while parked and cannot seem to reproduce it so its only while moving. Last year when I started hearing the noise I checked the forums here and most suggested the intake boot which was also the case for me. So I had that replaced but it did not completely get rid of the whistle but I gave up on it. It is now bothering me back again so I checked the intake boot and its still new with no tears/holes (even on the underside).
Couple of other suggestions I found on the forums were to check the vaccuum hoses but I don't know where to look for them. Also read that a vaccuum leak would lead to a higher fuel trim. So I plugged in a scanner with live data and the STFT would jump no more than 3% (this is only while parked. Did not test while driving)
Any suggestions would be appreciated and thank you.

[admranger]

Maybe the pressure regulating valves (PRVs) are the problem?

The CCV - CrankCase Ventilation is the whole ventilation system - the Pressure Regulating Valve is the part 99% of people are talking about when they mention CCV for the N62. The M62 V8 had issues with an Oil Separator canister that is not present on the N62s. The PRV’s are like $12 each from a dealer. They consist of a rubber membrane and a spring. Nothing fancy, and not likely to resolve your problems unless one of them is torn…but the tear would just be exacerbating the underlying issue, not the cause of it. The underlying issue would be the vacuum leak the could cause a PRV to plug and then tear. Fix the vacuum leak and then fix any torn PRVs

http://www.xoutpost.com/bmw-sav-foru...lue-smoke.html

It's a bit of a read, but it could be the cause. Cheap parts so might be worth a shot.

[garfield81]

Kirk
Thanks for the reply. I will look for a PRV replacement guide but a question, since I didn't mention this in the post earlier, is this applicable to 3.0 as the post link points to a 4.4 X.

Thanks again

[Doru]

The whistling noise on a i6 is usually associated with a torn rubber boot. Check the big rubber boot at the "Y" connection. Check part #8 in this diagram:



If the "Y" is intact, it might be another rubber hose or a bad rubber seal somewhere else (O-ring), which you could try and find by using some carb cleaner, or another vacuum leak method.

[garfield81]

Hi Doru
Yes part number 8 is the one I replaced about a year ago and it still seems new with no tears.

[Doru]

Originally Posted by garfield81

Hi Doru
Yes part number 8 is the one I replaced about a year ago and it still seems new with no tears.

OK. I would check the rubber boots again, just to be sure (the accordion ridges). If everything checks OK, you might want to see if you don't have a leak at the DISA level. The DISA has an integrated O-ring, with a very small rib. The rib fails prior to 70 k miles, and small vacuum leak is created, which could also cause a whistling.
The DISA valve itself, fails at around 100k miles. It has a plastic/nylon rotating axle, that will get eaten up in time, and the flapper that controls the air for low grunt doesn't do the job anymore. Also, the top steel pin loosens up and can fall in the engine, ruining it (GAS has a repair kit, which is much cheaper than a new DISA valve - I have that one in my e39, and it's working better than a new DISA).
The problem if you remove the DISA is that there is no replacement O-ring to seal the valve. If you get the DISA repair kit, you will get a replacement O-ring. You could also go online or some hardware stores and find an O-ring similar to what GAS sell - they are cheap, but you have to make sure they are heat and hydrocarbon resistant. The old O-ring, which is probably toast, you will have to scoop it out with a pick or a small screw driver.
Another location could be a torn plastic CCV hose. To change the CCV, it's a royal PITA, because the space is small, and there is a certain procedure on how to attach the upper hose that goes from the intake manifold into the CCV and is routed between the intake manifold and the distribution piece at a certain angle. If you need help with that, I can link you some references from another BMW forum or 2.

[Doru]

I just remembered: the DISA opens up at around 2k rpm, so maybe the DISA O-ring is buggered up. In that case, I would service the whole DISA or replace it with a new one. And whilst I am there, I would take off the TB & ICV and clean them really well. Last year, when I cleaned the ICV, it was blocked solid (and I wonder how I didn't get any codes), but after cleaning, it started to move freely again, just like new. The TB was also caked, and a good cleaning was in order as well. Both these items are right there, once you remove the DISA. Another 5 minutes tops.

P.S.: If you change the DISA O-ring, you have to take extra care when you re-install the unit. The new O-ring is bigger, and in order to fit, you have to slightly lube it, then squeeze the DISA back by pushing it very GENTLY, turning it back and forth as you press it in. Don't force it in, because the new O-ring will disintegrate otherwise. trust me on that.

[admranger]

Originally Posted by garfield81

Kirk
Thanks for the reply. I will look for a PRV replacement guide but a question, since I didn't mention this in the post earlier, is this applicable to 3.0 as the post link points to a 4.4 X.

Thanks again

My bad...reading comprehension fail on my part. I believe it only applies to the N62 V8.

[garfield81]

Originally Posted by Doru

I just remembered: the DISA opens up at around 2k rpm, so maybe the DISA O-ring is buggered up. In that case, I would service the whole DISA or replace it with a new one. And whilst I am there, I would take off the TB & ICV and clean them really well. Last year, when I cleaned the ICV, it was blocked solid (and I wonder how I didn't get any codes), but after cleaning, it started to move freely again, just like new. The TB was also caked, and a good cleaning was in order as well. Both these items are right there, once you remove the DISA. Another 5 minutes tops.

P.S.: If you change the DISA O-ring, you have to take extra care when you re-install the unit. The new O-ring is bigger, and in order to fit, you have to slightly lube it, then squeeze the DISA back by pushing it very GENTLY, turning it back and forth as you press it in. Don't force it in, because the new O-ring will disintegrate otherwise. trust me on that.

Hi Doru
Thank you for your reply. I finally got to pull out the DISA unit and I flap looks good as in it has a good spring motion. Also the vacuum seems good as I tried to cover the air hole and it holds the flap in place. One thing I did notice is there was a thin coat of oil on the flap. So my question is if the presence of oil on the flap normal?
Since the flap is in good condition I am going to order a O ring since the one on there right now is totally flat. Also you mentioned that I need to lube the new O ring. What type of a lube would you recommend?

Thanks again.

[garfield81]

Originally Posted by admranger

My bad...reading comprehension fail on my part. I believe it only applies to the N62 V8.

Hi Kirk,
That's my fault actually since I modified the post with the engine size after your first reply.