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  #1  
Old 06-01-2021, 04:45 PM
urquattrogus urquattrogus is offline
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Default Removing the Viscous Fan?

Has anyone done this?

A viscous fan was quite old fashioned even when the car was new? Also surprised the S54 has one too.

I have put a new fan clutch on mine just recently.

To some degree if it ain't broke, but I was just wondering...

However, the fan can be quite noisy and surely must add extra inertia to the engine as it's directly connected to the crankshaft.

I think there are supplementary electric fans? Its not uncommon to have one large electric fan and then afterun fans.

This then puts more load on the alternator and in term that takes some power to drive, but in general I was thinking a thermostatic electric fan might be more efficient?

Anyway, just got me thinking!
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Old 06-01-2021, 06:31 PM
Mad Max Mad Max is offline
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I removed my viscous back in 2014, before you do it though check that your AC fan works and fit the 88*C temp switch to the rad, the standard one is 95*C, it just gives you a bit more safety doing it.

The difference isn't night and day, but it is there. I only use my car in the summer and I've had no issues with oil or water temps, in fact my water temp always sits just to the left of centre.

Going back through my invoices the PN for the switch is 61.31.8.376.440.

Last edited by Mad Max; 06-01-2021 at 06:32 PM. Reason: Typo
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  #3  
Old 08-01-2021, 10:51 AM
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c_w c_w is offline
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As above, my car has not had a viscous fan on for years. A lower temp thermoswitch in the radiator itself will activate the from A/C "auxillary" fan at a more reasonable temperature (about 3/4 on the gauge), but this would only happen in hot summer days. If there is a concern just put the blowers on hot to drag heat off, but also as above the car really doesn't need that big fan hanging off the end.

Just FYI, the stock temp sensor leaves the aux fan off until it's nearly in the red! which is why many people think it's just for the A/C.

I actually put a manual switch on my car using a standard Z3 front/rear fog switch assembly (front fog will activate the fan on a simple circuit), so I can manually override and switch it on earlier or leave it to come on automatically.
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Old 08-01-2021, 11:06 AM
urquattrogus urquattrogus is offline
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Thanks, did either of you notice any difference to the way the engine revs?
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Old 08-01-2021, 06:29 PM
Mad Max Mad Max is offline
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Yes - you'll notice a little difference. If you combine it with an e46 M3 crank pulley, which is slightly smaller than stock, you'll notice it a little more.
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Old 09-01-2021, 01:50 PM
urquattrogus urquattrogus is offline
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Thanks, might try it out at some point. I have a new water pump to fit at some point as preventative maintenance so maybe when I’m replacing the coolant I might also try the lower temp switch and with/without the fan.
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  #7  
Old 10-01-2021, 07:16 PM
M1ke M1ke is offline
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Also removed Fan several years ago and fitted lower temp sensor - no issues experienced - also improves access to front of engine for belts / vanos.
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  #8  
Old 27-01-2021, 10:38 AM
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137699 137699 is offline
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After having seen this mod done on the Wheeler Dealers episode on their S52 it has me wondering if this is worth doing on the S50.

There was talk on the show of the fan blades connecting with the shroud and effectively detonating and causing significant damage.... is this an S52 issue or does this happen on the S50 also - and if so, how commonplace is this problem?

I'm in two minds about the whole thing - on the show they showed not only fitting the different rad switch, but also a different water pump/pulley & belt - which sounds great but then I wonder in future if it goes into a garage and they don't know about this mod they might go fitting the wrong parts and cause an issue in the future (for me or a future owner).

So... is leaving the viscous fan in place just asking for trouble - is it a time bomb waiting to go off and cause a major issue, or is this an overblown issue that doesn't affect the S50, or never really happens...?

Interested to hear opinions / battle scars!
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  #9  
Old 27-01-2021, 11:08 AM
urquattrogus urquattrogus is offline
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Nothing overtly wrong with the viscous fan, but I suggest you check yours for play and do a spin test etc.

If you fit a new viscous fan clutch and check the fan blades themselves for damage then I don't think you would have much to worry about.

I fitted a new fan clutch as mine was on it's way out.

When the fan is off and belts off it's worth checking for play in the waterpump.

My waterpump was fine but i have a new pump to put on in the near future as preventative maintenance.

The reason I'm considering dropping mine is that I hate the noise at idle and feel it must add a bit of drag to the engine and also put a bit of extra strain on the waterpump bearing.

Another good preventative thing is to replace all of the auxiliary belt tensioners and belts if not done for some time.

Last edited by urquattrogus; 27-01-2021 at 11:10 AM.
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  #10  
Old 05-02-2021, 03:35 PM
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Not on the MC but have done this on 4x4s.....changed for an electric fan on a switch for deep water crossings. It stops the blades being smashed by the water resistance.
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