Howling noise as rpms rise

Swees · 04-05-2011, 02:41 PM

More often than not now I get a howling sound as my rpms rise. I have read some similar posts saying it is the intake boot. I attached this video I took on my to work this morning. Kinda hard to hear, but looking for some opinions. I visually inspected the elbow and it looks fine although I didn't get down in dirty this morning. I am also throwing codes about the secondary airflow too low on all cylinders. Wondering if this could be related. Thanks!

cvx5832 · 04-05-2011, 03:24 PM

Do you have a mechanical fan on your car, ie the fan is physically attached to the water pump? If yes -

With the motor off, can you spin the fan freely?

Paolo

OrientBlau · 04-05-2011, 03:35 PM

The so-called "semi truck" sound is caused by the clutch fan as stated above.

Here's another way to test it. With the car parked in idle, see if you can slow and stop the fan with your hand or a newspaper. Gently see if you can stop the resistence of the spining fan.

PLEASE BE CAREFUL. Ive done the test and ended up getting a new fan clutch on my automatic, as it was very weak.

Heres a video I found on YT:

.

Swees · 04-05-2011, 04:34 PM

I can't spin the fan when off and can't be stopped at idle.

cvx5832 · 04-05-2011, 05:47 PM

Quote:

Originally Posted by Swees

I can't spin the fan when off and can't be stopped at idle.

Then your fan clutch needs replacing.

Careful driving that around. Reports here of fans throwing blades at high rpm. I don't think those fans were meant to spin 1:1 with the water pump.

Replace it as soon as you can. Research the tools you need. It's a quick swap.

I emphasize not waiting too long to get that replaced. When the blades go, you could lose a radiator, some hoses, your fan shroud, and maybe even your hood.

Paolo

Swees · 04-05-2011, 09:59 PM

Alright got the 32mm wrench and water pump hub holder off ebay for $47 (almost as much as the fan clutch) and took the car to my parents house where I snagged my dads z3 until the parts come. Thanks for the help!

YOnpds · 02-14-2012, 01:22 PM

Quote:

Originally Posted by Swees

Alright got the 32mm wrench and water pump hub holder off ebay for $47 (almost as much as the fan clutch) and took the car to my parents house where I snagged my dads z3 until the parts come. Thanks for the help!

Did you fix the "howling" noise issue?

04-05-2011, 02:41 PM	#1
Swees Registered User Join Date: Jan 2010 Location: Pittsburgh Posts: 33 My Ride: 2005 325xi View My Garage	Howling noise as rpms rise More often than not now I get a howling sound as my rpms rise. I have read some similar posts saying it is the intake boot. I attached this video I took on my to work this morning. Kinda hard to hear, but looking for some opinions. I visually inspected the elbow and it looks fine although I didn't get down in dirty this morning. I am also throwing codes about the secondary airflow too low on all cylinders. Wondering if this could be related. Thanks!

04-05-2011, 03:24 PM	#2
cvx5832 Registered User Join Date: Mar 2009 Location: Walnut Creek, CA Posts: 1,044 My Ride: 325Ci, 325Cic, C300 View My Garage	Do you have a mechanical fan on your car, ie the fan is physically attached to the water pump? If yes - With the motor off, can you spin the fan freely? Paolo __________________

04-05-2011, 03:35 PM	#3
OrientBlau Registered User Join Date: Jul 2010 Location: NYC Posts: 2,453 My Ride: 2003 330i View My Garage	The so-called "semi truck" sound is caused by the clutch fan as stated above. Here's another way to test it. With the car parked in idle, see if you can slow and stop the fan with your hand or a newspaper. Gently see if you can stop the resistence of the spining fan. PLEASE BE CAREFUL. Ive done the test and ended up getting a new fan clutch on my automatic, as it was very weak. Heres a video I found on YT: . __________________ All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Arthur Schopenhauer

04-05-2011, 04:34 PM	#4
Swees Registered User Join Date: Jan 2010 Location: Pittsburgh Posts: 33 My Ride: 2005 325xi View My Garage	I can't spin the fan when off and can't be stopped at idle. Last edited by Swees; 04-05-2011 at 05:30 PM.

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04-05-2011, 09:59 PM	#6
Swees Registered User Join Date: Jan 2010 Location: Pittsburgh Posts: 33 My Ride: 2005 325xi View My Garage	Alright got the 32mm wrench and water pump hub holder off ebay for $47 (almost as much as the fan clutch) and took the car to my parents house where I snagged my dads z3 until the parts come. Thanks for the help!