Cooling fan issue

[Ianmc]

The problem I have had since buying the Z3 M44 12 months ago is that the electric fan doesn't come on on its own. When sat in traffic for more than a few minutes, the water temp gauge starts to climb. Turning on the aircon starts the fan and the needle comes back to normal (middle of gauge).

Have replaced radiator and thermostat (for other reasons) recently. My research shows that there is a cooling fan (for aircon) high speed relay (K22) and a normal speed relay (K21) for the cooling fan. K22 is clearly OK (aircon works) so have today replaced K21, with no improvement. Found the (illusive) F48, 40amp cooling circuit fuse today (its behind the glove box) that has not blown. Replaced the radiator sensor a few months ago.

Any other ideas please? Could be a wiring continuity issue or faulty fan I suppose, but it looks in good nick and works from the aircon circuit very well. Any other thoughts would be most welcome

 

[Dino D]

On a few o the early 2.8 the fan was wired incorrectly by the factory so never worked on low speed.
Will dig out a thread with all the details so you can check as sounds the same as what I had

 

[Dino D]

Between buying in 2011 and the next major update in Feb 2015 I'll list the things I did.

The car was pressed in to dual service - my daily commute which was around 40 miles each way for some great A roads, bit of Motorway and some dual carriage way. It was a pleasure for this sort of drive and the top was always down on those summer and winter evenings, a great way to clear the head from a days work at the office.

First mod:
CG Lock seat belt stabilizer:
View attachment 72434
With the firm suspension and grippy rubber you would come out of the seat before the car ran out of grip! Especially with the standard seats.
So this went in and is still in 6yrs later - brilliant device and doesn't to seem to be available for sale any more in 2018?

Soon followed by a seat lifter/incline kit which lifts up the seat front and hold you better in the seat, reducing the submarine effect under braking where you slide out the seat pretty much:
View attachment 72437
(Internet image, I never took pics!).

I now use one of @Southernboy s kits on my Sparcos as I need less lift, but am so used to the slight tilt it feels odd not having it:
https://zroadster.org/pages/Southernboys-BMW-Z3-Modifications/


The car was actually used weekdays and on most weekends it stood still. Was a real treat to use it daily on decent roads.

It had lots of maintenance in that time - regular oil, filters etc. Always used branded oils and genuine filters
Tyres - rears at twice the rate of fronts - the way it should be

Top tip re doubling tyre life: I found that that swapping the tyres on the rime so the outside is then the inside doubled tyre life - with the rear camber I run from lowering and a lot of wear happening on acceleration as it squats and messes with camber/toe the insides would go very quickly. Worth keeping in mind when choosing tyres- I used to run Falken 452 back then. Now not many tyres let you do this, but the Hankook Ventus V12 I have now do. They do not have an 'outside' marker just direction so you can swap them over on the rims form side to side.

Cooling system - I was somewhat unlucky in that I've had 2 viscous fans break apart and 2 clutch fan units fail in the open position - that rubbish design is now banished from my car forever and now only runs a brand new aircon fan (which is standard on aircon equipped cars).
Here is thread from when I replaced my seized the air con fan using a e36 unit (identical bar some excess plastic trim and half the price - was around £100 compare with £200+ for the 'Z3' item:
https://zroadster.org/threads/electric-fan.7828/


Important info for MK1 2.8 Owners re the electric aircon fan wiring here:

I think the quote function worked above but if not see post #3 here: https://zroadster.org/threads/dino-ds-z3-2-8-custom-build-98-montreal-blue.17140/#post-286366

 

[Ianmc]

Dino, that's amazing, thank you very much. Had never heard of this before. Is the plug referred to (where the wires might be incorrectly inserted) the one that joins the sensor fitted to the radiator? Mine is a very early 1997 car so could well be this.
Cheers, Ian

 

[Dino D]

Dino, that's amazing, thank you very much. Had never heard of this before. Is the plug referred to (where the wires might be incorrectly inserted) the one that joins the sensor fitted to the radiator? Mine is a very early 1997 car so could well be this.
Cheers, Ian

I think it was sensor plug yes , was a few years ago now!

 

[Ianmc]

Dino, brilliant outcome, @Dino D did as you suggested and the fan now comes on on its own when water temperature is reached.
For ease of reference for others:
Plug is on RHS of radiator, easily unplugged from sensor.
Swapped black/grey wire into what was brown wires socket.
Brown goes into what was black/green socket.
Black/green goes where black/grey wire was.
5 minute job, dead easy to do.
The plug and its wires looked "undisturbed". Amazing that this car appears to have been incorrectly wired for 20 years.
Again, many thanks for the steer.
Ian

 

[Dino D]

Interesting that’s it’s not just a 2.8 thing but seems early car thing.

It only becomes apparent on the 2.8 when the viscous packs in/you remove it so never had any idea until then. Running without the viscous now and the fan wired correctly and works fine.

Does yours have a viscous too? Just wondering how it’s been driving so long like that otherwise!

Could also explain why you see so many 4pots being scrapped due to HG failure?

 

[Mazza]

Wrong wiring seems to be a thing with the Z3. When I fitted the heated seats in mine I found the relay base where I had to insert the heated seat relay was wired backwards. Obviously been like it since the day the car was assembled as up till then never been used.

 

[Ianmc]

Interesting that’s it’s not just a 2.8 thing but seems early car thing.

It only becomes apparent on the 2.8 when the viscous packs in/you remove it so never had any idea until then. Running without the viscous now and the fan wired correctly and works fine.

Does yours have a viscous too? Just wondering how it’s been driving so long like that otherwise!

Could also explain why you see so many 4pots being scrapped due to HG failure?

No viscous on the 1.9 M44 or indeed (normal) fan. Just the one electric fan engine side of the radiator, a "puller" I assume. Works for both the aircon and (now!!!) engine cooling.
You may well have a point regarding HG failure, fortunately mine is fine but....... I think previous owners of the car used the A/C a lot (3 ladies!), the whole system (condensor/dryer etc) was replaced in 2007 and still works perfectly. This might explain how the issue was (perhaps unwittingly) mitigated.

Definitely worth owners of early cars (if not all) checking this out. Defo owe you a beer or two Dino!!