Z4 E85 3.0 - 2005 - will not start!

knmstag · Post by **knmstag** » Thu Jul 22, 2021 1:52 pm

My son Ryan has a BMW Z4 E85 3.0 (2005). He loves the car, but we have not been able to get it started for a couple of weeks now!

I have checked the battery, alternator and starter motor, and all is OK. I have checked fuses & earth connections, and still no joy.
We have ordered a new ignition switch which should arrive tomorrow, I was wondering if the car key could be at fault...

Car is located in Burton on Trent. Any suggestions please?
Thanks - Kevin (Coventry)

bigwinn · Post by **bigwinn** » Thu Jul 22, 2021 2:08 pm

Hi Kevin

Is it turning over or nothing at all

Lights on dash?

Cheers

Stuart

enuff_zed · Post by **enuff_zed** » Thu Jul 22, 2021 2:12 pm

Hi Kevin,
Someone had a similar issue last week.
That turned out to be the battery. It showed 14.1v but (I'm no electrician) it wasn't pushing out enough amps to turn it over.
Diagnosed by jumping it from another car. Have you tried that?

knmstag · Post by **knmstag** » Thu Jul 22, 2021 3:39 pm

Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!

enuff_zed · Post by **enuff_zed** » Thu Jul 22, 2021 4:00 pm

knmstag wrote: ↑Thu Jul 22, 2021 3:39 pm Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!

Well there is history of the ignition switches failing, so fingers crossed its that simple.

bigwinn · Post by **bigwinn** » Thu Jul 22, 2021 4:23 pm

enuff_zed wrote: ↑Thu Jul 22, 2021 4:00 pm
knmstag wrote: ↑Thu Jul 22, 2021 3:39 pm Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!
Well there is history of the ignition switches failing, so fingers crossed its that simple.

That’s where I’d be leaning toward

No history of any aftermarket immobilisers fitted?

Zedebee · Post by **Zedebee** » Thu Jul 22, 2021 5:08 pm

Sorry you’re having difficulties. How do you know the starter motor is OK? This is quite a common failure and a do-able DIY fix.

knmstag · Post by **knmstag** » Thu Jul 22, 2021 5:49 pm

Thanks for message. I removed the starter motor and tested it on the bench, using a spare car battery. Earthed the casting body, positive supply on terminal post, and bridged across ignition switch terminal. Gear pinion moved rearwards and was rotating at speed, all sounded fine. I therefore assume starter motor is OK.

knmstag · Post by **knmstag** » Thu Jul 22, 2021 5:57 pm

Just in case anyone needs to remove the starter motor on a Z4, you do not need to remove the inlet manifold!
It’s possible to remove it on LHS, by removing air cleaner box and air mass sensor components. Thanks to YouTube video!

knmstag · Post by **knmstag** » Thu Jul 22, 2021 10:53 pm

The new ignition switch arrived today, was fitted, but has not solved the problem. I plan to get a new key from a local auto. key specialist, but we are feeling very frustrated, having tried various potential causes, but still baffled!

enuff_zed · Post by **enuff_zed** » Fri Jul 23, 2021 7:44 am

One last stab.
Is it an auto? Wondering if it could be a failure of an inhibit switch if so? Thinking it's not in Park?

knmstag · Post by **knmstag** » Fri Jul 23, 2021 8:09 am

It’s a manual gearbox. I’m going to get a new key, as that can be a problem if it can no longer be read by the lock barrel. Thanks to all for suggestions.
Kevin

enuff_zed · Post by **enuff_zed** » Fri Jul 23, 2021 8:38 am

knmstag wrote: ↑Fri Jul 23, 2021 8:09 am It’s a manual gearbox. I’m going to get a new key, as that can be a problem if it can no longer be read by the lock barrel. Thanks to all for suggestions.
Kevin

Is it not possible to reprogramme the old key?
Don't you have a second key to try?
Unlikely for both to fail.

Mike6 · Post by **Mike6** » Fri Jul 23, 2021 2:16 pm

I am the person with the fully charged battery with not enough amps to turn the starter motor. In this case I am still veering towards battery/starter motor. But the fact you tried a jump from another car does make me wonder a bit as mine then fired first turn of key. If engine is not turning it can only be a couple of things as circuit run directly from battery to starter via ignition. Not sure about failing battery in key, possibly a good try. I think these can be recharged enough by placing key next to a toothbrush charger.
You say you tested starter motor on a bench but it wasnt fitting against engine compression and additional forces. That still leads me to question the starter motor.

knmstag · Post by **knmstag** » Fri Jul 23, 2021 6:15 pm

Thanks for support.
I will try a heavy duty battery from my Jaguar XJS, so worth a try. I will also check the voltage supply once again.
I plan to get one of the keys reprogrammed tomorrow.
It’s a process of elimination, albeit time consuming.
The Z4 is not the easiest car to work on!

Z4-forum.com

Z4-forum.com