Viscous Fan Delete Modification

[Nodzed]

Removed the Viscous fan today and changed the fan sensor switch for an 80 / 88. Didn't have to remove the rad cowl just undo the nut and slide up and out happy days.

No leaks no overheating on a good hard run, needle in the middle in fact it never ran in the middle with the viscous attached so I am assuming it was over cooling, so here's hoping it works OK on a very long run, guess I will find out on Sunday driving to Beaulieu (@mid life crisis bring a tow rope )
The is engine quieter too no fan howl Good mod if you have the aux fan.

@roadvoyager1 Thanks for your help mate.

 

[bruce&kim]

done my 2.8 with this http://www.mishimoto.co.uk/mishimoto-bmw-z3-aluminum-radiator-99-02.html had no aux fan so also purchased the slimline fan http://www.mishimoto.co.uk/mishimoto-slim-line-electric-radiator-fan-14.html and changed temp switch and its been great for 3 years

 

[bruce&kim]

then it blew up... ......................... no its been fine and never overheats

 

[Nodzed]

done my 2.8 with this http://www.mishimoto.co.uk/mishimoto-bmw-z3-aluminum-radiator-99-02.html had no aux fan so also purchased the slimline fan http://www.mishimoto.co.uk/mishimoto-slim-line-electric-radiator-fan-14.html and changed temp switch and its been great for 3 years

Glad you've had no issues If I'm honest I was a little worried about doing it but enough people had posted here and other forums saying it was OK have you noticed any improvement in fuel consumption or do you have a lead right foot and don't care

Niall

@mid life crisis check out the slim line fan link.

 

[bruce&kim]

fall into the don't care category Niall I am afraid....but I am a lot hap
ier without a viscous fan...

 

[Nodzed]

Thought I would update this with a word of caution!

I realise others have done this mod to 2.8s etc not sure it works on an ///M

Think before you remove your viscous.

Since doing this mod I have no issues until recently. The car has not over heated in normal driving, traffic queues, hot weather etc etc,. However two things have happened recently that has motivated me to put the viscous fan back on.
Firstly last Saturday evening whilst travelling to a mates house a starling crashed through my lower grill and into the fan which has no guard on the lower part. I didn't realise this had happened until I was sat with the car ticking over talking to my mate and the temp gauge started to go up, quick investigation found the before mentioned bird jamming the fan.

Next while out on a very enjoyable run yesterday with Low Rider in hot weather and during a very very spirited drive up a long twisty hill, up went the temp gauge again (first time this has happened whilst driving)

So here's the thing,
1. If you are relying totally on the aux fan and it fails or jams there's no back up (I would fit dual fans going forward)
2. (and this may be just on the ///M where it revs higher??) If the weather is hot and your driving the car hard the standard aux fan wont cope in certain circumstances.

So my viscous is back on today and she is standard again and staying that way just in case and before any damage is done.

N

 

[roadvoyager1]

No problem with mine and over 2,000 miles since delete, however, I will be checking out the fan protection guard very soon!

Thanks for the heads up on this one.

 

[andyglym]

Interesting read chaps, thanks. Permission to sound thick? I have a 2.8 and have a fan on the engine side and a fan on the front of the rad. I've yet to see the one on the front move yet (have left it running on idle for ages). The one on the inside appears to run all the time, I think. The needle sits bang in the middle and no over heating issues.

1. Which is the viscous fan?

2. What is the other fan and when should it kick in?

3. Despite having blead it to death I can't get hot air out unless I'm moving, never at idle. New rad, water pump and thermostat fitted but the symptoms are still the same.

Thanks Team

 

[Dino D]

I'm not sure your second scenario is linked to the lack of viscous fan unless you were revving very high but going very slowly so not much air flowing.

The fact your car was running cooler than it should have with the viscous fan in place indicates all is not well in your cooling system and should be checked out I think.

The viscous kicks in based on the temperature (not via a sensor but via the oil in the coupling I believe) so perhaps the coupling is faulty or something else like thermostat needs checking.
Even if the fan was blowing more that it should I don't think it could over cool the coolant as they coolant flow is controlled by the thermostat anyway so should only flow when at temp and the temp reading for the dash is taken from a sensor in the head not radiator (as far as I understand, I'm no expert but read up plenty before doing the mod).

 

[Dino D]

Interesting read chaps, thanks. Permission to sound thick? I have a 2.8 and have a fan on the engine side and a fan on the front of the rad. I've yet to see the one on the front move yet (have left it running on idle for ages). The one on the inside appears to run all the time, I think. The needle sits bang in the middle and no over heating issues.

1. Which is the viscous fan?

2. What is the other fan and when should it kick in?

3. Despite having blead it to death I can't get hot air out unless I'm moving, never at idle. New rad, water pump and thermostat fitted but the symptoms are still the same.

Thanks Team

The viscous is the one on the engine.

The aux fan is on the front. It should kick one when idling for long periods on slow speed and on fast speed when the aircon is on.

Some early 2.8's including mine were wired incorrectly from the American factory so the aux fan didn't kick in at low speed ever, only on high speed with the AC on.

I'll dig up the thread about this so you can test yours. Edit here is the thread @Andy McDonnell https://zroadster.org/threads/fan-delete.7136/

Not sure why you not getting hot air but most likely to do with the heater matrix or plumbing.

 

[andyglym]

The viscous is the one on the engine.

The aux fan is on the front. It should kick one when idling for long periods on slow speed and on fast speed when the aircon is on.

Some early 2.8's including mine were wired incorrectly from the American factory so the aux fan didn't kick in at low speed ever, only on high speed with the AC on.

I'll dig up the thread about this so you can test yours.

Not sure why you not getting hot air but most likely to do with the heater matrix or plumbing.

@Dino D many thanks. I've done all the usual stuff of pumping the pipes, raising the front and bleeding etc. Toasty at speed but barely tepid on tick over. Thanks again

 

[Nodzed]

I'm not sure your second scenario is linked to the lack of viscous fan unless you were revving very high but going very slowly so not much air flowing.

The fact your car was running cooler than it should have with the viscous fan in place indicates all is not well in your cooling system and should be checked out I think.

The viscous kicks in based on the temperature (not via a sensor but via the oil in the coupling I believe) so perhaps the coupling is faulty or something else like thermostat needs checking.
Even if the fan was blowing more that it should I don't think it could over cool the coolant as they coolant flow is controlled by the thermostat anyway so should only flow when at temp and the temp reading for the dash is taken from a sensor in the head not radiator (as far as I understand, I'm no expert but read up plenty before doing the mod).

It was only running slightly cooler with the viscous in place nothing to worry about, and i am going to change the pump, thermostat and belts in the winter, and yes I was belting her, around 7000rpm in low gears so no high speeds for about a mile up hill on a hot day, the aux fan just isn't designed to cope with that, it is after all a back up to the viscous in extreme events.
The temp gauge is controlled and damped (buffered) by the ECU that's why the gauge doesn't fluctuate during normal driving when in fact your car temp will change from 90 to 120 (or higher) regularly, you just dont know it because the ECU is damping the gauge, its normal, if the gauge starts to move up then the temp is getting well out of range.

The problem was definitely because of hard driving as I have had no issues even sitting in traffic on a hot day (Beaulieu) I guess BMW know best in fitting the viscous and a back up fan, so no arguing from me I'll leave it standard.

 

[Nodzed]

Oh yeh forgot the viscous is oil controlled so if the viscous is damaged or just not operating correctly then this will affect your cooling, either over cooling or (not common under cooling) if a viscous fails it will fail to safe and lock up giving over cooling to prevent engine damage.

 

[Dino D]

Such high revs and low gears with no air flow sound like the right recipe for a extreme temps.

I hear what you are saying about the buffering but the same applies if it was running cold - so if your needle was less then centre it was running something under 90c which is also not right.

Brian H posted up about a dashboard test you can do to see the actual temp reading from the sensor rather than a buffered reading, will dig it up so you can check it out.

 

[Dino D]

Here it is:

Dino,

Below is a chart I made some time ago which from the information I could gather at the time seemed to indicate the temp range of the car.

I had my 1.9 at the time and no INPA so reading the hex codes was not too easy. I know the cooling system is pressurised allowing for higher temps but running at 120 - 130 degrees does seem a little high. The later speedo heads give a temp reading in degrees when using the test mode, I'll run my car tomorrow and get some feedback for you as to the temp I am running at.

 

[Nodzed]

Such high revs and low gears with no air flow sound like the right recipe for a extreme temps.

I hear what you are saying about the buffering but the same applies if it was running cold - so if your needle was less then centre it was running something under 90c which is also not right.

Brian H posted up about a dashboard test you can do to see the actual temp reading from the sensor rather than a buffered reading, will dig it up so you can check it out.

Cheers mate, I know she runs slightly cool and drops when coasting down long hills with the viscous on so its most prob the thermostat, so she will get some TLC once the season is over.

 

[Nodzed]

Here it is:

Jeeze either my eyes don't work or that's small is there a link for this?

 

[Dino D]

Oh yeh forgot the viscous is oil controlled so if the viscous is damaged or just not operating correctly then this will affect your cooling, either over cooling or (not common under cooling) if a viscous fails it will fail to safe and lock up giving over cooling to prevent engine damage.

In my experience it didn't work that way - two couplings failed (both genuine) and in both cases they didn't lock, instead they never locked up at all so the fan did nothing. Because mybaux fan was wired incorrectly in America it never kicked in so it started getting hot. On another occasion the viscous fan lost blades and nearly pierced the radiator.

Even it were locked to blow all the time I'm not sure it can cause a low reading on the dash - the dash gets it temp reading from the sensor in the head - the coolant to the head is controlled by the thermostat which remains closed if the coolant was not hot enough (can't remember what the temp is).

I remember reading that in normal temps it's not possible for the fan reduce the coolant temp so far that the thermostat won't open.

Maybe the thermostat is stuck open hence getting cool readings with the viscous in place?

 

[Dino D]

Jeeze either my eyes don't work or that's small is there a link for this?

It's your eyes...









Click on the pic and it will open bigger. If you on your phone you can then save the image to your camer roll and zoom in so you don't have to get you reading glasses out

 

[Althulas]

Tap on the image to expand works on my iPhone.

A job I've got to do on mine so ordered a water pump, fan blade assembly, belts and pulleys. I have a new non oem viscous which I bought years ago in ignorance not knowing if it will be up to task but can stop my old one at by grabbing the fan blades with protective glove at cold.