A favor needed from all the 4.8is owners out there…

[Ash977]

I have a strange noise (cricket sound) coming thru the AC vents to the cabin on my car (2006 BMW X5 4.8is with 38K miles) when driving around 60 mph. I believe the source of the noise is the engine.

So when I am driving around 60 miles per hour I hear a combination of grinding/cricket noise coming through the middle AC vents. I guess the air flow becomes a medium to carry the noise to the cabin. I can’t hear anything when the car is stationary.

I need your help to pin point the source of this noise. The best way to isolate this noise is:
1-“Auto” or the middle air distributor (face) on the climate control should be picked. The fan speed should be on minimum.
2-Preferably driving on a smooth road to minimize tire noise with closed windows.
3-Drive up to 60 miles and put the transmission in “N”
4-Press the gas pedal slightly, revving the engine between idle to about 2,000 rpm.
5-Listen closely for any grinding noise that comes thru the middle vents.

This noise has been driving me crazy and there is no way for me to isolate. I just want to see if other N62B44 engines make the same noise.

I am hoping someone has experienced this issue before or there is an explanation for it. .

Thanks in advance…

[Ash977]

I changed the write up above a little bit. This noise sounds like a cricket trapped in the engine… Hopefully someone can shed some light on this…
Thanks,

[jst2878]

sounds like a pulley. have someone rev the engine and check the belts and Alternator pullley

[DUCATI5]

Does the frequency of the ticking increase and decrease with the rpms of the engine? If not then you could simply have gotten a leaf or someone stuck in the fan blower assembly. Kinda like when you'd put a playing card in the spokes of your bicycle tire as a kid to make the same type of cricket sound.
Please forgive me if you have already eliminated this theory. Just trying to evaluate every possible explanation.

[Ash977]

jst2878 – Thank you for your comment. I live in an apartment and unfortunately I don’t have the luxury of working on my car. I need to find a shop and have them check out the pulley. I know the dealer changed the AC tensioner pulley not too long ago. I might have another bad one that the dealer just didn’t catch.

DUCATI5 – Thank you for your comment. The noise depends on the engine rpm. I had the leaf problem (actually with a parking stub paper) on my E46. I know exactly how that one sounds... In my case, the noise sounds like a hybrid of grinding and cricket noise and depends on the engine rpm.

[tomcat]

Hi. Mine has a cricket sound coming from the air vents, but I believe it is actually the fan. Really odd, but under acceleration doesn't appear. As soon as I let off the gas or brake it starts chirping. Won't shut up unless I turn the fan all the way off. Figure I'll have to pull of panels and lube the fan to put an end to it.
The engine does have a high pitch wine to it, but don't notice it while driving so much as sitting idle outside the vehicle. Every SA I've talked to has said that was normal.
Good Luck,
Scott

[britcon]

Might be a bearing in the Fan motor ? Maybe when you hit 60mph it puts enuf air pressure in the system to load the bearing ?

[PropellerHead]

On the E39, this was most commonly the air temperature intake fan on the A/C unit. It's behind the little grills on the A/C unit beneath the display. It develops a high pitched chirp. Often, compressed air will solve the issue, but I don't recall if the fans can be ordered by themselves. It has also been diagnosed as the FSU.

[Ash977]

Scott – thank you for your reply. I thought about the fan being the culprit. However, changing the fan speed doesn’t affect the noise at all. Also, at least in my case, the fan doesn’t make any noise when stationary. I do hear the grinding noise under acceleration as well. When I let go of the gas the grinding noise becomes easier to be heard due to less noise coming from the engine.

Yes, when I turn the fan off or reroute the air to top and bottom vents (take a face/middle outlet out) the sound disappears. But the grinding/cricket noise does change with revving the engine.

britcon - Thank you for your comment. You might be very well right. However, I like to know (if anyone knows this) do you think revving the engine with change the air inflow to the blades of the HVAC fan? If that’s the case, the fan bearing can be the cause of the noise. How expensive is it to change the motor???

PropellerHead - Thank you for your comment. The noise is coming thru the middle (face) vents. Plus, it can’t be heard when stationary and changes with the engine rpm.