View Full Version : BMW Bromley

12-12-2006, 09:38 PM
Popped in to have a look at the z4m coupe, (it has lots of toys in it), and was £45k according to salesperson, while I was their I asked service dept about my fan not working on 1- 3 settings, guy said hourly labour rate was £155, and it would take 1/2 hour to diagnose what the problem might be,

Seemed a little too much to me, just as well they couldn't book me in until next week :-)

12-12-2006, 10:05 PM
what about bexley motorworks, thats not to far

13-12-2006, 12:32 AM
1/2 hour to diagnose the problem at those rates is just criminal. I'll do it now for free, and I know none of the details of how the system works.

You slow an electric motor by feeding it a lower voltage, and the easiest way to do that is to use a resistor. The control in the car will switch in and out different resistors to give 4 different voltages (the top one will have no resistor).

Given that the fan works fine on one setting, one of the switch, the resistor, or the wiring between the two is buggered. Given that it's the top one (no resistor) that works, I'd put my money on the resistor. Bear in mind, that when you're on setting 1, the resistor will be soaking up 75% of the energy that the fan uses on full pelt. That's quite a lot, and the resistor will get hot. It's probably cracked.

2 min on realoem.com reveals that the switch costs $18, and the resistor $24. The part number on the latter is 64111375754 (but double check for your exact model).

A quick Google found this, which seems to confirm my diagnosis:


Now, all you've got to do is figure out where it is on a Z3:


So, for £20 and 45 minutes you could have it fixed.

... and if I'm wrong you'll have invested less than it'd cost you to have the stealer "diagnose" the problem.

It really pisses me off that someone charging £155/hour isn't competent to give an on-the-spot diagnosis of something that obvious (and, seemingly, common). Do they have any experience at all? Would you trust them to use a screwdriver near your car?


13-12-2006, 09:39 AM

You are probably right. This is a common problem on all BMW's with the same type of fan system.

13-12-2006, 09:51 AM

Thanks for your help on this, I will buy the parts and fit them myself.

My BMW TIS discs arrived this morning :-) so now I can do it all, and pay myself £150 P/H for my expertise:-)

have a great Christmas :-)

13-12-2006, 09:57 AM
Good luck - look forward to hearing how it goes.

I've ordered some isopropyl alcohol to clean the MAF on mine, as per exdos' suggestion. Will be interested to hear if £6 of spray will avoid a trip to a garage.