Replaced radiator fan on 23i, but does it work?

[q149]

Recently I noticed a sort of squealing from under the bonnet from time to time. Especially when I stopped at crossroads or right after cutting the engine because the radiator fan always seems to stop rotating at that moment. The noise was coming from the radiator fan. When the engine was off and cold, the fan was clearly making the squealing sound when moved by hand and it didn't rotate smoothly at all. I ordered an aftermarket replacement fan with housing from autodoc and swapped the old one with it thanks to the clear explanation on this forum from member jonnymac in https://z4-forum.com/forum/viewtopic.php?t=136415.

All good so far. I went for a long test drive and the temperature gauge finally ended up somewhere between 110 - 120 C° but never higher than that, the same as with the old fan. No overheating detected. So i suspect the new fan does its job? Just to be sure, when the engine was warm enough I stopped a few times during my test drive with the engine still running and took a quick look under the bonnet, but I could never actually see the fan turning. It was always stationary, I guess that's normal.

Not being a car mechanic my question is: how can I be 100% sure that this new replacement fan really works? Suppose it didn't work, would the car overheat? Would the engine temps have gone > 120 degrees? Also I read the error memory but no errors.

 

[Pondrew]

Turn the A/C on. If it works as it should the fan will cycle with the a/c condenser temp. Simples.

 

[q149]

Turn the A/C on. If it works as it should the fan will cycle with the a/c condenser temp. Simples.

Not sure if the AC was on when I did my visual checks. Do you mean the fan should definitely run when the AC is switched on, asking a cool temperature?

However, I did put the AC on at the end of the test drive with no noticable effect on the temperature gauge.

 

[B21]

The temp you’re measuring is the oil temp not water temp..there’s no direct correlation between coolant temp and oil temp..

If there was an issue with the coolant fan you’d get a coolant over temp warming pretty quickly…yellow then red..

FWIW

 

[Pondrew]

Not sure if the AC was on when I did my visual checks. Do you mean the fan should definitely run when the AC is switched on, asking a cool temperature?

The fan cycles with the A/C on (on high side pressure). It doesn't automatically run full time unlike many cars. But it should kick in quite quickly, quicker than waiting for the coolant to reach 105 degrees (or whatever it is).

As Peter said above, your temp gauge reads oil temp. Your electric fan is controlled by coolant temp (and a/c pressure).

 

[q149]

As Peter said above, your temp gauge reads oil temp. Your electric fan is controlled by coolant temp (and a/c pressure).

Ok guys, thank you both for refreshing my knowledge . I used to know that, but I forgot about it. After the pretty long test run I did without any issue and a working A/C, I think I can be sure that the new fan does its job.