New owner, door locking issue, need help

[Red2.5]

Greetings all, located in Tacoma Washington, USA. We just purchased a 2000 Z3 2.5 to replace my wife's car and I've been sorting through a few issues. One was the old classic "spinning door lock" problem and as is often found, the cap, spring and block had popped out. They were all located in the door, reassembled and sealed inside again, fixing the spinning issue. Now however the door does not lock or unlock with the key (we don't have a FOB). It did ONE time (locked), but not since. Both the doors and trunk (boot) lock and unlock normally with the key when used in the passenger door or trunk, but there is no activity and I don't think anything occurs when I use the key in the driver's door. Is this likely the micro-switch, or is there something mechanically wrong with the lock, or both? I thought it odd that I cannot manually lock the car with the key, but I'm not familiar with how BMW does things like this. Are the switches serviceable in some manner (cleaning, etc) or is it a replacement only part? Your insight and knowledge are GREATLY appreciated.

Fixes I have done so far include the sliding seat issue (bushings, worked great), replacing the rear window (a bit of a battle, eh... hope it seals), dying the soft top black (came out good vs the old tan), replacing spark plugs (71K miles), the mentioned spinning door lock issue, and I'm about to send the subwoofer speaker off to be refoamed since they can't be found anywhere (2ohm speaker).

My knowledge base on Z3s is growing, but I'm much more used to the simplicity of my '67 Datsun SRL311 2000 Roadster. I've had that car for over 36 years, and recently completed a conversion from Dellorto sidedraft carburetors with an electronic distributor to Jenvey Heritage EFI and a Ford EDIS crank-fired ignition system. I'm very active on the site that supports Datsun Roadsters (311s.org if you're curious), and I hope to help out someone here on Zroadster.net in the future.

Thanks again in advance for any help offered.

[LaRy]

Hi, maybe this explanation can help you: https://www.bimmerforums.com/forum/show ... -in-detail

Some years ago I had some problems. I removed the locking mechanism from the car and cleaned it from old dry grease by using brake cleaner spray. It was really old and dry. I added some new grease and after that everything is working great.

[Red2.5]

Thank you for your suggestion. These systems are much more involved than anything I've ever seen in my classic Datsun!

So I gather that 1) I should be able to lock the door mechanically/manually with the key?
2) I can still have a failing micro switch at the drivers door even if it still locks/unlocks from the passenger/trunk actuation?

I'm hoping that I can swap out the door micro switch and fix this... yes?

[LaRy]

I have the feeling that the microswitch at the lock is working "one step ahead" of the mechanical connection to the door closing mechanism. Also the drivers door is locked/unlocked by the electrical actuator, not by you by turning the key. The rod between the lock and the door closing mechanism is only in use if the battery is dead.

For this reason, it is so important that the old grease is removed and the door mechanism easily can be controlled by the actuator.

[Red2.5]

Thank you. I will investigate how the lock itself functions in more depth. I noted the key had a spring feel to it but I don't recall feeling a mechanical engagement. When I was reassembling it I spun the key/barrel around until it caught and created that spring feeling, and the key was vertical. Is there a specific position for all of this that "sets it up"? It this what you mean by the MS being "one step ahead" of the mechanical? Something works, as the door will lock and unlock remotely.

I greatly appreciate the continued guidance. I really want my wife to love this car after her previous, near perfect "one owner" car got totalled by another driver.

[LaRy]

It sounds like the microswitch does not work.
What I mean by one step ahead is the feeling that the microswitch is telling the central to unlock all doors and trunk, including the drivers door. You never feel that you actually are unlocking the door by pushing some rod when twisting the key.
Is the microswitch in the right position after your lock repair work?

[Red2.5]

Understood, thank you. I didn't mess with the switch at all. Given that it worked ONCE, you're probably right. I will go ahead and order a new switch, and when I've got the door panel off again will clean the original switch with electrical contact cleaner, clean out any old grease, relube the lock as suggested, and see if I can observe what works. I didn't want to order an electrical part unless I needed it, as things like that are often not returnable if it turned out to not be the problem. Worst case scenario I will have a spare! I'd rather have what I may need to fix it than deal with the door panel RnR more times than necessary. I expect to be better at it the second time...

Thank you very much for the input! I will post the repair to finalize the thread.

[LaRy]

I would check the wires from the microswitch by a multimeter. check for contact when turning the key.
How to get the mechanism out : https://www.youtube.com/watch?v=7OUu2JFPLzo
This video shows a E36M43, but when looking for used parts and instructions, a lot of parts are very similar with the 3 series .

[Red2.5]

Thank you LaRy, will do. I have a new switch coming in a few days but will check things out before installing it and report back.

Just watched the video above... fortunately the switch I'm addressing is on top of the handle/lock and I'm anticipating an easier RnR!

[LaRy]

i know where the switch is placed and hopefully the problem is in the switch. But at the same time, my advice is to clean and re-grease the door lock.

[Red2.5]

Fun note... just ran the vin on my car, and I learned a few things...

Since getting the car a few weeks ago, I've since determined it's been repainted in an area, likely after unreported cosmetic damage was repaired (very well done, but I can see the over spray signs. No frame damage). I'd also noted it had a 2.5i badge on it, but as I've been researching these cars they didn't come with that badging until it had the M54/B25 engjne, not available until 2001 (and mine is clearly a 2000). Running the vin today revealed that it has the M52TUB25 engine, which for whatever reason was badged as a 2.3 in the States. This suggests that the badging was replaced, and again I'm thinking incorrectly as a 2.5i, or they replaced the trunk lid with one that had a 2.5i emblem on it already (seems all original, paint on fasteners etc intact however). I guess it doesn't bother me, except that I realize things are not always what they seem to Be! Fortunately the car seems very solid so far. And there are no broken welds in the trunk (first thing I had them check before I bought the car).

[LaRy]

Here you can read the story explaining 2.3 and 2.5 l engines: https://www.autotrader.com/car-news/bmw ... ine-274344

[Red2.5]

Here you can read the story explaining 2.3 and 2.5 l engines: https://www.autotrader.com/car-news/bmw ... ine-274344

Thank you, similar to my own summation of what I could find. And since my car was manufactured on 12/99, before they changed the badging in 2001, I'd say something has been changed or replaced on my car eh! I don't mind, as we have this car as a daily driver for my wife, and I'm more concerned about it being reliable and functional than correct". I did however look up parts needed for the M54B25 engine since it was the "2.5i" engine, before I ran the vin #. When we were searching for a replacement, we had to go all the way across the country to find one that wasn't abused, red like her old one, decent mileage/history (ha! Clearly not completely accurate) and an automatic (she can't drive a manual, yet anyway). They were very hard fo find. This still appears to be a good car.

Door switch just arrived...

[LaRy]

New owner...... . I also have an automatic. An auto gearbox expert told me to change oil when I bought mine. BMW auto gearboxes needs fresh oil, maybe your oil is now 20 years old.
If you have to change oil, it is not an easy procedure on the Z3, double oil pans, have to check oil temperature when refilling and so on. Use an expert for this job.

[Red2.5]

Thank you for the guidance. I will research it and see if I can find any history of a change... sounds unlikely given the difficulty. I must say, it's a really nice shifting box... barely notice it change gears. I noticed the rear diff was a bit whiney or made a little more noise than the previous ones I've heard, though they all have had a mechanical whirring (1.9, have also had 2 others with the 2.5). This is with the top up, mainly under acceleration. No BAD sounds (clunks, bangs etc), just a whine. Thoughts?

[LaRy]

When I bought mine, I changed ALL oil, auto gearbox, engine and the rear diff. I also have whining diff, especially att certain speed. No change during the last 10 years since I bought it. We have to accept that the Z3 has almost nothing of noise damping mats. You hear everything. But oil change is definitely not going to make any harm.
Unfortunately, European car makers never recommend oil change in the auto gearbox. But if it is a taxi, yes. How does the gearbox knows?
The truth (according to me): Without oil change, the auto gearbox will survive the warranty time. After that, the customer will have to buy a new or renovated gearbox. Good profit!

[Red2.5]

Greetings all, thought I'd finish out this thread now that I fixed the door lock issue (see above). Well, it turned out the issue was not the micro-switch, but the broken plastic connector that secures the locking arm that dangles down from the handle unit that then connects to another arm that actuates the lock. Hard to describe unless you've been in there, but the plastic piece clips to the dangling arm which keeps the two arms together. I broke the securing end when I failed to unclip the plastic piece from the arm when I was removing the lock/handle mechanism before. After assembly the first time, the force of shutting the door a time or two caused the arm to simply pop out of place. I figured this was not an easy part to find, so I elected to use a small zip tie properly position in such a way as to keep the two arms secured together, and now the key works to operate the lock normally... yeah! Now of course I'm stuck with a new micro-switch that I may never use (I've collected a couple hundred dollars in parts like that in my tool box over the years!) but one could have the odd hope that I may need it someday...

Thanks again to the info provided. Hope this helps someone down the road. BTW, the worst part of this job is getting the darn door panel back on. The biggest issue is getting the top edge of the panel to slide into the slot that secures it. I ended up spraying on a bit of Teflon lube on the edge of the panel, and that helped a great deal in sliding that on more easily.