Viscous delete or stay as is

[DaveP]

Driving the Z3 Kobra yesterday and today I have found that the viscous fan is always on and makes a roaring sound as I go up through the revs. I shall find a good independent to take a look at replacing the clutch or ask them regarding moving to an electric using thermostat control. I'm leaning towards a straight swap but wonder if any mileage in the delete approach?
I may also get them to look at a water pump replacement too if they are in there. Not sure if still on original and it's done 102k miles.

Secondary question is what make replacement should they source. Lots of them online and I don't have BMW discount. Question is about clutch and waterpump.

Thanks all.

Dave

 

[Duncodin]

I had a bad bearing on mine that made a hell of a racket. Trying to shake it with the belt on didn't feel like it was bad but once I'd got the belt off the bearing was so loose I'm surprised it stayed on.

Anyway. Replaced it and now it's fine. When it's cold it should pretty much free-wheel quietly. You can stop it with your fingers (do not do this at home )

 

[Dxbolton]

Lots of people in the states delete the fan with no issues, and it’s generally warmer over there. You’ll probably be fine without it

 

[SV8Predator]

What is a "Z3 Kobra" — sounds interesting!

 

[Duncodin]

What is a "Z3 Kobra" — sounds interesting!

I think they're referring to the 'Kobra' body kit for z3

https://www.classiccoachworks.org/kobra

There's a few different kits about. Ferrari, the kobra, some 'generic' classics and @Dxbolton is building a BMW 507 Tribute. I've order a 507 kit too and I'm watching and learning from Dxbolton's most excellent progress thread. If mine turns out half as nice as his I'll be well chuffed.

 

[Dxbolton]

I think they're referring to the 'Kobra' body kit for z3

https://www.classiccoachworks.org/kobra

View attachment 277141

There's a few different kits about. Ferrari, the kobra, some 'generic' classics and @Dxbolton is building a BMW 507 Tribute. I've order a 507 kit too and I'm watching and learning from Dxbolton's most excellent progress thread. If mine turns out half as nice as his I'll be well chuffed.

Thank you for the kind compliments, it’s a blast to drive and turns many heads

 

[Duncodin]

Thank you for the kind compliments . . . . .

Yes. But I gotta stay in your good books for when I come begging for advice.

 

[the Nefyn cat]

I took the viscous fan off mine a few years ago and it hasn't caused any problems. Yet. And that's in the sub-tropical paradise that is North Wales. Try it without and keep an eye on the temperature gauge, if it does go high there's a very fine heater in these cars that can dump a lot of heat, it may be uncomfortable but shouldn't take long to get the temperature down. Haven't had to resort to that, but round here we don't have a lot in the way of traffic, especially now the tourists have gone home. Hurrah and harrumble.

 

[t-tony]

And now you can't go fast enough to get any amount of airflow either

Tony.

 

[the Nefyn cat]

Think you'll find that the 20mph stuff applies to built-up areas, and since they can't be ar5ed to enforce the 30 limits it won't make a whole lot of difference. Quite happy to see cars doing 20 through the middle of Nefyn, and, who knows, perhaps some of the speed bumps'll disappear.

 

[t-tony]

No chance on the speed humps, that'll cost money.

Tony.

 

[Richard29]

Is there a how to guide anywhere to delete the fan?

 

[t-tony]

Where have you looked? If you search on the magnifying glass on the page header, type in the search box "viscous cooling fan delete" and you'll find lots of threads to read.

Tony.

 

[Dino D]

I’ve deleted the viscous BUT have aircon and had to ensure the aircon (auxiliary) fan was working properly as that kicks in to cool. It’s electric and pushes air through aircon condenser and then radiator - it’s clearly visible from the front airdam and only there if you have aircon.

this thread should help

Electric fan

Hi All, I'm sure I have seen some good write ups on removing the viscous fan & fitting an electric one, if the thread is around & someone can point me to it I would be gratful. I would like to do this on my 2.0Ltr. I would prefer to fit a fan in front of the rad, for a couple of reasons, more...

zroadster.org

I ran the car to years like this.
It took a 30c plus track day at Lydden Hill for it to run the gauge past halfway but even then a couple of cool down laps and it was ok.

As the track days increased I tried adding the viscous but had issues with that so added an aftermarket electric set up instead.

I’ll dig out a link to that.

If you are not doing track work then the aircon fan is plenty.
Oh and if not an M engine - those need a viscous or replacement electric as they generate much more power and heat.

 

[Nodzed]

Oh and if not an M engine - those need a vicious or replacement electric as they generate much more power and heat.

Agree

 

[Dino D]

Agree

Yep they are’ vicious’

I think it was you that mentioned it ran hot on hilly roads.

In the US people have run M’s fine with just the aircon fan but we need to remember their M’s are not the high output S50.
Think their ones only make 240bhp vs 300+ for S50?

 

[Nodzed]

Yep they are’ vicious’

I think it was you that mentioned it ran hot on hilly roads.

In the US people have run M’s fine with just the aircon fan but we need to remember their M’s are not the high output S50.
Think their ones only make 240bhp vs 300+ for S50?

It only happened once on a very spirited drive on a hot day up a very long uphill twisty road, but that once too often, also had an incident where a sparrow decided to jam up the aux fan, it went back as Mr. BMW built it

 

[DaveP]

thanks all for your answers. I think I will get a new viscous fan as that's how bmw designed it and who am i to argue and make major changes to my car

 

[DaveP]

What is a "Z3 Kobra" — sounds interesting!

Hi,

It is a rebody of the Z3 that makes it look like a 60s convertible, it will never be a cobra but I like it. My build thread is here if you are at a loss to spend a while reading it.

Dave

https://www.zroadster.org/threads/z3-to-kobra-build-thread.22419/

 

[Mike Fishwick]

I often find that on high alpine passes, afterIi have taken a quick photo with the engine still running, that the viscous fan cuts in, showing that the aircon fan cannnot keep pace with the high temperature and heat soak from the engine.
I would never dump the viscous fan, as electric fans can also have their problems, so a backup is worth having. A new coupling costs about £75, but an electric fan motor can cost a lot more.