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7 Series - E38 (1995 - 2001)

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  #1  
Old 03-11-2014, 09:36 AM
injuhneer injuhneer is offline
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Location: Arizona
 
Join Date: Feb 2014
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Mein Auto: 740iL
Door Lock Actuator - Failure modes and repairs

So after just a few weeks of ownership I had the privilege of the driver door lock actuator failing. In this case the mechanism was stuck in a position that:

A) Would not allow the door latch to lock
B) Would not run the actuator

After removing the lock to see why the actuator wasn't working I opened the actuator to have a look.

Browsing online showed there are several failure modes for these little actuators. Micro switch failures. Motor failures, etc.

This case was due to deformation of the actuator frame. One would think that after so many years of using nylon that the designers would know that plastic creeps. The best place for plastic to rest is unstressed otherwise it creeps to relieve stress.

The result is the end of the frame that is also the thrust bearing for the actuator screw is stressed at least part of the time. Over time the plastic has deformed and cracked. The excess end play allowed the ramp for the micro switch to over travel and not return.

Fortunately these actuators are inexpensive and available so I'll order a couple to keep on hand.

Because I am not very patient I'll repair this failed unit.

The plan is to mill the end frame (thrust bearing) flat and make a large Delring hat bushing to fit in. The bushing will distribute the thrust over a larger area and set the screw position back to its original position.

Anyway, this is probably overkill for most folks who would just swap it out.

-Mike O.
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  #2  
Old 03-11-2014, 09:39 AM
sigtwenty sigtwenty is offline
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Or for $42 on amazon you can buy a new oem vdo branded unit

I bought 8 of them when they were $37 each. (2 cars 8 doors)

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Last edited by sigtwenty; 03-11-2014 at 09:40 AM.
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  #3  
Old 03-11-2014, 09:47 AM
injuhneer injuhneer is offline
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The failure

Here are photos of the failure. I'll post some of the fix later.



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  #4  
Old 03-11-2014, 10:02 AM
injuhneer injuhneer is offline
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Quote:
Originally Posted by sigtwenty View Post
Or for $42 on amazon you can buy a new oem vdo branded unit

I bought 8 of them when they were $37 each. (2 cars 8 doors)

Sent from BimmerApp mobile app
True enough. Of course if it has the same design flaw it will fail eventually too.

I enjoy fixing things particularly if it can be improved.

I am interested in what other common failures folks have seen in these.

-Mike O.
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  #5  
Old 03-11-2014, 10:16 AM
FABOCH's Avatar
FABOCH FABOCH is offline
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Mein Auto: 2000 BMW 740I SPORT
Ive done every job on my 7 that needed replacement...I mean everything ( F + R suspensions, timing guides, full interior swap, Brakes, rotors etc etc)....1 thing I could NOT do was removing the acutators without breaking the mounts that hold the actuator in place inside the door....I was WTF?? ( tried to practice on 4 e38 junk yard cars so I dont ruin my 7,lol )...Installing these damn things would require the smallest hands in the world , no? My Drivers door had "open door" error on cluster and side mirror wasnt working via switch...What ended up NOT being a bad actuator on my driver`s door ended up being a bad window switch module....Yup you heard correctly a bad driver window switch module...I replaced my window switches from a junk yard car awhile back...DIDNt know it was defective until the driver mirror couldnt be operated via switch...I bought a new Window switch module and driver and side mirror started working again....What a FIx huh???...
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  #6  
Old 03-11-2014, 11:36 AM
injuhneer injuhneer is offline
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Quote:
Originally Posted by FABOCH View Post
Ive done every job on my 7 that needed replacement...I mean everything ( F + R suspensions, timing guides, full interior swap, Brakes, rotors etc etc)....1 thing I could NOT do was removing the acutators without breaking the mounts that hold the actuator in place inside the door...
Indeed. I have bear paws for hands so they are not dainty enough to reach in and swap the actuator in-situ. I took the whole mess out to check the lock itself. That is when I foudn the over-travel problem in the actuator. It had gone past the micro switch and could not reverse itself.

Some of the dependencies between these systems are interesting.

I did just finish a front-end rebuild on my car. That was actually pretty simple/

-Mike O
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  #7  
Old 03-12-2014, 08:10 AM
injuhneer injuhneer is offline
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Location: Arizona
 
Join Date: Feb 2014
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Quote:
Originally Posted by sigtwenty View Post
Or for $42 on amazon you can buy a new oem vdo branded unit

I bought 8 of them when they were $37 each. (2 cars 8 doors)

Sent from BimmerApp mobile app
I found VDO branded units on ebay for $19.00. Anyone have experience with the Standard Motor part?

-Mike O
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  #8  
Old 03-13-2014, 06:09 PM
sigtwenty sigtwenty is offline
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Quote:
Originally Posted by injuhneer View Post
True enough. Of course if it has the same design flaw it will fail eventually too.

I enjoy fixing things particularly if it can be improved.

I am interested in what other common failures folks have seen in these.

-Mike O.
Yea but it takes 15 years....I removed 3 from my car before they actually failed because one did and deadlocked my car and I busted a door panel to get it open. The other 3 had signs of the bubbling but not too bad.

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  #9  
Old 03-13-2014, 06:10 PM
sigtwenty sigtwenty is offline
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Location: vegas
 
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Mein Auto: e38
Quote:
Originally Posted by injuhneer View Post
I found VDO branded units on ebay for $19.00. Anyone have experience with the Standard Motor part?

-Mike O
What is standard motor part? A brand?

I have 5 vdo being used and all perfect.

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  #10  
Old 03-13-2014, 08:13 PM
injuhneer injuhneer is offline
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Location: Arizona
 
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SMP? Standard Motor Parts?

http://smpcorp.com/ROOT-Home/Content.aspx

Theirs is STANDARD MOTOR PRODUCTS DLA460

There is an AIRTEX / WELLS 8D1383.

And Dorman 746-508:

http://www.dormanproducts.com/gsearc...tuator%20Motor

They may all be the same unit just re-branded.

-Mike O

Last edited by injuhneer; 03-13-2014 at 08:17 PM. Reason: corrections
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