164 door won't stay locked; Oil suggestions

["C.M. Smith" <cmsmith@domain.elided>]

The only defect on my 91 164L when the dealer attempted to get me to accept
delivery (unsuccessfully, until it was fixed) was a left rear door which
refused to allow the car to stay locked with the power locks. Each door has
a "proximity" switch to detect whether the door is fully closed or not. If
not fully closed according to this switch, the car will repeatedly unlock
itself (presumably to warn you not to leave it unattended as bad people
might take up residence therein, or just take...). The fix is careful
adjustment (yeah right) or replacement of the offending switch. The left
rear door on my car is still a bit temperamental. It set off the alarm just
recently as the switch decided a little late that the closed door really
wasn't closed tight enough and triggered the alarm even though the door
appeared to be, and felt, tightly closed. I think this is part of the
intrusion alarm system which goes off if anyone attempts to force the door,
even if unsuccessful (ask me why I needed to replace my first cracked
driver's door handle). Highly amusing that the door refuses to lock until
it's really locked, sort of.

Aw shucks, just when I thought I had this pegged I did two foolish things.
First I checked the factory shop manual. The "proximity" switch is integral
with the door lock motor, both are replaced as a unit, adjustment seems
somewhat hypothetical, if barely feasible. Also, the manual also shows the
standard "door closed" piston type switch mounted on the center door pillar
for the rear doors. No such beast on my car, just a plastic blanking plug
(secret hi tech magnetic switch? not bl**dy likely).

Then I checked the car itself for various permutations of door locking and
partly closed doors, and could not duplicate symptoms actually experienced
in the field on more than one occasion. Car "locks" fine  with a rear door
latched but not securely closed, and blithely leaves the rear door
unlocked, allowing peaceful alarm free entry!!!! So much for controlled
experimentation. Maybe the global warming guys could score more grant money
by figuring out the actual scientific principles governing normal Alfa
operation (oxymoron I suspect).

Anyway, you're on the right track with the door lock "motors'. Just be
aware they incorporate a "door lock sensor" which I suspect is the root of
your problem. This also signals the "Alfa Romeo Control Unit" (another
oxymoron, does anyone control these cars?) to switch off the interior
lights. Hence the plastic blanking plate where the door closed switch
normally (there's that word again) resides, creating the illusion of a high
tech proximity switch, which may actually be lurking inside the door as
part of the door lock solenoid.

Oil again! Yes Agip Sint is their synthetic oil, safe for ALFAs, and mine
is enjoying sipping delicately on about 8 liters of the stuff since the
last change to 5W 50 Agip Sint 2000 (Chanel #5 would probably be cheaper,
but my wife is a jealous woman, so oil stink is safer)

Michael Smith
Calgary, Alberta
Canada
91 Alfa 164L, White, original owner 

------------------------------