More on fan noise

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therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

More on fan noise

Post by therealdb1 »

Hi all,
I have a 2000 2 litre and intermittently it started to make a racket like a jet engine when hot. Now it does it all of the time I've decided I need to do something about it.
The symptoms are that with a cold engine everything is fine but once the engine is up to temperature it sounds like a fan is running much faster than intended but the speed is proportional to engine rpm. I have therefore ruled out the electric fan on the bumper side of the radiator as surely this would run at fixed speed, also the usual exhaust emissions contraption that makes a noise on start up but not during hot running and point the accusing finger at the viscous clutch. I have checked it with the engine off and the fan will rotate with resistance either hot or cold but I am reluctant to try the rolled newspaper test given that my suspicion is that the clutch is locked solid and I may damage the fan blades, the radiator, or my wrist.
I know that the clutches often fail and do not drive the fan so the engine overheats but the engine temperature on my Z is stable at running temperature. It just seems an odd failure that it releases with the engine stopped but locks up when running hot.
It does not appear to affect the performance it is just horrendously noisy.
Before I replace the viscous coupling has anyone come across this mode of failure or have any alternative ideas?
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: More on fan noise

Post by Mike Fishwick »

The air con condensor fan in front ofthe radiator will start when the A/C is in use - with a short delay after pressing the A/C button. It is quite noisey, and also operates as the usual engine cooling fan, the viscous coupled fan on the water pump shaft cutting in at a higher temperature. The viscous fan sounds like a fire siren. If you unplug the water temperature sensor for the a/c fan - on the off side of the radiator - you will soon tell if this is the noise you hear. Obviously, it runs at a steady sped - well, two steady speeds, so as you suggest, the viscous couped fan looks like the culprit.

The viscous fan should rotate with only very slight resistance at low temperatures - just a slight drag. You could always remove it to check for it being the source of the noise. a 32 mm spanner is required, and ideally a pulley locking device - see the Z3 Knowledgebase for details of mine, which does not require the pulley bolts to be removed.

If the viscous coupling is engaged, do not run the engine at more than about 2000 rpm, as its operation places a high load on the fan blades, which have been known to break off and damage the radiator.
A Z3 is not just for Christmas - it's for life!
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: More on fan noise

Post by Del »

As far as I know, these viscous fan couplings can seize either way i.e. so that they "freewheel" all the time and as you say, the engine can overheat, or they can be incorrectly "engaged" all the time. Furthermore, it has been reported on many BMW forums that the cheap aftermarket versions can be extremely noisy. I believe the originals were made by Sachs and give many years of trouble-free operation.
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: More on fan noise

Post by Mike Fishwick »

60 to 70,000 is an average life
A Z3 is not just for Christmas - it's for life!
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Koolflyer
Joined: Fri 05 Jul, 2013 15:51
Posts: 586

  Z3 roadster 2.8

Re: More on fan noise

Post by Koolflyer »

Hi, think you better view this topic as it sounds like you have the same problem as me. The viscous clutch fitted to mine was only 2000 miles old (June 2013), but a cheap one. Barry Deadman, Leicester (ex Sytner) fitted a new Sachs clutch which sorted it out. My old clutch not only sounded awful but more to the point it was very stiff when turned by hand, on the new one there is just a small amount of resistance. Either that, or it's just old and cream crackered, but either way I'd get it replaced with a good quality one.

http://www.zroadster.net/forum/viewtopi ... =5&t=39850
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Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: More on fan noise

Post by Mike Fishwick »

My current viscous coupling - about £75 from GSF - is not almost 70,000 miles old, so on any long run I always carry tools to remove it, but so far it seems fine. When it fails I will probably not replace it, and rely on the electric air con fan, as on the E46 models.
A Z3 is not just for Christmas - it's for life!
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Mad Max
Joined: Sun 28 Feb, 2010 11:18
Posts: 442

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Re: More on fan noise

Post by Mad Max »

I did the viscous delete a few days ago, I've been happy with the results. You can feel the difference with less parasitic drag on the engine, plus a lower temp fan switch means the AC fan kicks in sooner.
therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

Re: More on fan noise

Post by therealdb1 »

Thanks to everyone who has replied.
I've eliminated the electric fan by disconnecting the switch as Mike suggested. Once I've procured a 32mm spanner I'll whip off the viscous coupling and give it a try just to confirm although with 120,000 miles on the clock with what looks to be an original part it's been lucky to get this far by the experiences shared on this forum! Probably time for a new one anyway while I'm taking the old one off. I'll see if I can get hold of a Sachs unit for a good price.
Thanks again, guys.
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: More on fan noise

Post by Southernboy »

...... once you get a 32mm socket, just remember the nut is a reverse thread.... so don't try undoing it in the more common direction... :wink:
"Normal is overrated"
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therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

Re: More on fan noise

Post by therealdb1 »

Just an update.
My car did indeed have a BMW branded fan clutch so it could well be the original fitment especially since to remove it I destroyed my first water pump locking bar and had to make a new one from much more solid steel. Yes I did remember that the fan has a left hand thread but the nut was well rusted and probably hasn't been touched for 14 years!
A new OEM clutch appears to have fixed the 'wooshing' sound so now I just need to find the source of the squeak on the offside front suspension. Very annoying!
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: More on fan noise

Post by Del »

Squeak/clink going over bumps - possibly the drop-links.
pedro20001
Joined: Sat 29 Jan, 2011 20:34
Posts: 361

  Z3 roadster 2.2i
Location: tamworth

Re: More on fan noise

Post by pedro20001 »

Regarding the viscous fan deletion what's needed and does the air con need to be on for the fan to operate?
therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

Re: More on fan noise

Post by therealdb1 »

Cheers Del. I'll look into those for starters.

Pedro, when I was checking my electric fan it started up with the ignition on but the engine wasn't even running so no the air con doesn't need to be on. If you are going to remove the viscous coupled fan I suggest that you do check that the electric one is operational on both speeds as they are prone to seizing. It's easy to do with a short piece of wire by removing the connector from the radiator switch and short the centre pin of the plug to either of the outer pins. One side shall be fast the other slow.
pedro20001
Joined: Sat 29 Jan, 2011 20:34
Posts: 361

  Z3 roadster 2.2i
Location: tamworth

Re: More on fan noise

Post by pedro20001 »

Cheers for that. I will have a play!
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