davintosh

First, a little background:
The door locks on my ’88 BMW 735i (e32) have been something of an enigma to me; they worked, but they worked differently than other cars I’ve had. Even differently when compared to my ’84 BMW 528e.

With the early BMW’s, locking the doors generally involves pushing down on the door lock knob before shutting the driver’s door or putting the key in the outside lock and turning it to the right; that locks all four doors, the trunk and the fuel filler door. To unlock them all, insert the key and turn it to the left. And the same trick works using the key in either front door or the trunk lock.

In the late ’80’s, BMW added a new feature known as the Deadbolt; it prevents the door from opening with anything but the key. To deadbolt the car you put the key in the door & turn it one notch farther to the right. I say ‘notch’ but there’s really no notch when you turn the lock; there’s no tactile, audible or visible indication that anything different has happened at all. The doors just appear to be locked. But they will not open unless you use a key to turn the lock, no matter what. Presumably, if I were sitting inside the car and someone turned the key to put the doors into deadlock mode, I’d be stuck in there until someone with a key unlocked the car from the outside. The lock knob will not move. No. Matter. What.

As with most well-intentioned systems like this, when everything is working properly, it works great and is a decent theft-deterrent… But throw two decades of use at a system that really has no prescribed maintenance schedule, and you have the potential for problems. And of course that’s what I’ve been dealing with. Story of my life.

Help! My Door Is Locked, And I Can’t Open It!

During a severe cold snap in early December, my son Ian went to use the car & tried to unlock an already unlocked door. He had only used the car a few times, and wasn’t very familiar with the way the locks worked; his fiddling with the key resulted in deadbolted doors. No big deal, I thought at first; I’ll just show him how it works & unlock them. But when turning the key as I should to unlock the car, the driver’s door stayed locked and shut; the other three doors unlocked and opened as expected. Great. I suspected and eventually confirmed that it was an issue with the door lock actuator, but getting to that point — and getting the door open — was a painful trial.

Of course, the car is my daily driver, so leaving it sit wasn’t an option. But driving it was a problem too, what with having to climb over the console or the driver’s seat back to get behind the wheel. So the door needed to be opened, but how? At first I thought the cold was the main culprit, so I did what I could to warm things up; no mean feat with the overnight temps below zero and not much better during the day. Ran the engine with the heat on full for an extended time; nothing. Used a heat gun to warm the outside of the door in the area of the actuator; nothing. Parked it in a heated garage overnight; nothing. All the while I was scouring the Internet looking for answers to how to get the locks working again. All signs pointed to an issue with the actuator, a broken bracket for the actuator, or a stuck lock mechanism. I was betting on the actuator (or its wiring) because I couldn’t hear a thunk in the door when the key was turned. Whatever the problem was, I needed to get inside the door to fix it, but with the door closed and no way to open it, that was a problem.

I had the deadbolt feature to thank for this predicament; deadbolting is intended to prevent a thief from prying the window open enough to get a slim jim or wire in to pull the lock knob. When in deadbolt mode, the actuator physically prevents the lock knob and its connecting rods from moving. The mechanism also has physical barriers — additional metal bits — that block access to the linkage with typical door unlocking tools. Most locksmiths who have dealt with BMW’s won’t even touch them. One guy that responded to my pleas for help on this issue told the sad story of his experience with it; his car ended up deadbolted where none of the doors would open. The car was towed to a BMW dealership where, after much deliberation, they eventually removed the windshield to gain access to the interior, then removed a door card to gain access to the locking mechanism; needless to say, they caused considerable damage in the process. That story made me cringe.

The Fix!
I was referred to a site where another guy had a similar problem with one of the rear doors; he was able to remove the door panel with the door closed, then fixed his issue from there. Many guys responding to my pleas for help at the mye28.com and BimmerBoard forums suggested I go that route, but try as I might, there was no way of getting the front door panel off without damaging the panel or the surrounding dash and trim. The wraparound dash/door vents and on the B-pillar overlap the door panel, essentially locking the door panel edges in place. To top it off, there is a bracket in the middle of the door panel that locks into the window regulator mechanism, and the panel must be slid upward to be released from the door… There was just no way to do any of that without damaging what was a pristine door panel in the process.

After much internal turmoil & deliberation (with myself!), I bit the bullet and cut a hole in the middle of the door panel to gain access to the actuator. I figured that, yes, I was causing damage to the panel, but it was at least controlled damage that could (presumably) be repaired much easier later on. After looking at some photos of the e32 door panel and the door mechanism posted by others online, it looked like the best place to cut was cut in the area just above the armrest. That location turned out to be perfect; once I removed the section I cut out, the actuator was right there! I loosened the bolts holding the actuator to its bracket, pushed back on the lock rod to unlock the door, pulled on the door latch rod, and the door opened! Success!

Cutting the door panel was — I think — pretty decently planned. I first cut the padded vinyl with the blade of a utility knife extended angled behind the overlapping pieces of the door panel, then cut vertically near the door pull handle. That way, most of the cut lines would be obscured by the overlapping pieces, leaving only the three-inch vertical cut near the door handle where a patch might be visible. Once I had the padded vinyl out of the way, it was just a matter of using a heavy utility knife to cut the particle board/cardboard panel behind it, and the moisture barrier behind that to reveal the door actuator servo. Once that was visible, getting the door open was simply a matter of removing the two screws holding the actuator in place and pushing the actuator and the linkage backward: Clunk, and the door was open! And to think I wrestled over that decision for nearly a week!

Like most of the issues I have with these old cars, this one has been a learning experience. Some of the things I learned:

• The locking mechanism on the BMW e32 is electrically actuated; the door lock is a key switch that sends power to an actuator servo to lock or unlock the door (the manual says that there is a manual unlock feature on the passenger door and sometimes the driver’s door, but I can’t get it to work.)
• The door locks are heated. If the temperature is below 38 F and you lift up on the outside door handle with the car locked, a heater in the lock energizes for 30 seconds to melt any ice from the lock.
• There is an inertia switch that disables the deadbolt system; if the car undergoes a shock of approximately 5g’s, all doors automatically unlock, and the hazard lights turn on. This allows rescue teams to more easily locate a wrecked car and gain entry.
• If the battery goes dead with the doors deadbolted, the only way to get them unlocked is to somehow apply power to the car and turn the key. Some have found that it’s possible to use jumper cables connected to the frame and a terminal under the car to temporarily power the car so that the door locks can be actuated. (Yes, I’ll be doubly diligent about making sure that the lights are turned off!)
• If the doors are simply locked and not deadbolted, and the battery goes dead, you might be able to use a wire tool of some kind to get at the lock knob through a closed window. Again, connecting jumper cables to the frame and a terminal under the car to can temporarily power the car so that the door locks can be actuated. I’m wondering now if discretely adding a terminal somewhere on the car that can temporarily power the locks wouldn’t be a good idea…

Well, the incident with the door locks happened in December, and here it is, almost March, and I still don’t have my door back together. But I have good reasons for that… I replaced the lock actuator with one from Nordstrom’s Ewe Pullet yard, and now the lock works fine, either by turning the key or pushing down on the lock knob inside the door. Opening the door from the inside is (more than) a little goofy in that I have to pull forward on the cable that normally attaches to the door handle. On the plus side, I found that the empty cavity at the bottom of the door is a great place to chill a bottle of Diet Coke on a cold-weather road trip! Actually, I’m holding out for some warmer weather before putting it back together, and doing a few other projects that involve the inside of that door:

• Remove the lock mechanism out to clean & refresh the grease in it.
• Clean the grease/dirt/whatever that’s collected at the bottom of the door and clean out the weep holes.
• Repair the rust on the outside of the door (and make sure/hope it hasn’t crept any farther.)
• Fix the window that complains & doesn’t like to go up & down as it should (this is almost complete; will likely do another post sometime soon on that.)
• Off Topic (just a little…) — I’ve also learned once again that the crew at MyE28.com is bar none the best online support for keeping these old BMW’s running.

I know that doesn’t sound like much, and certainly not what should delay buttoning things up for over two months, but I really hate working on things like that in a cold garage. I hate working on them when it’s really hot too, but… I’m tired of winter.

All in all, the 735i has worked out well for me. I’m reminded that I’ve been a bit remiss in posting much of anything about the car, so here are a few photos I took of it last week, after a much-needed wash. It really is a nice looking car, and in very decent shape for a 22 year old vehicle. It runs fantastically, but only drives ok, mostly due to some issues with the suspension and steering. I am in the process of procuring some parts to remedy that, and in the next month or so I will be spending some time rebuilding the front suspension and partially rebuilding the rear suspension… weather permitting of course.

This entry was posted on Saturday, February 27th, 2010 at 11:28 pm and is filed under Cars!, Geek, Just Stuff. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.