3 Series 1992 – 1999 (ex. ’92 Convertible)
(E36)
Thermostat Housing & Water
Pump
Pre-’98 had problems with plastic thermostat housing leakage
and failure of plastic impellers on water pumps. These have probably been
replaced on all of the effected vehicles by now.
Radiator
The plastic gets brittle and the
upper hose neck breaks. It appears that the hose has just come off,
but closer inspections reveals part of the radiator neck inside the
hose.
Water Damage
to Computer
Pre-’96 vehicles are susceptible to water
damage to the ECU (engine computer) when run through a car
wash. They had a single
water drain, on the passenger’s side, to drain water from the
windshield area. It has a short rubber tube leading down behind the
engine. Over time, the
tube becomes brittle, not opening well with water flow, and can
become plugged with debris (tree leaves, etc.). An automated car wash pours
water onto the windshield faster than the plugged drain can handle,
and some of the overflow runs into the compartment where the ECU
lives. The symptom is
failure to start after passing through the car wash. Repeated attempts to start
it may then damage the computer’s components. Sometimes, the ECU can be
saved by removal from the vehicle, removing the cover and blowing it
dry.
Rear
Shock Mounts
The upper
mounts for the rear shock absorbers are a normal wear item. As they age, their condition
goes to cracked rubber (no symptom, but your mechanic can see it
during inspection), then to completely broken out (rattling or
banging going over bumps).
Front
Control Arm Bushings
The rubber bushings, which isolate unwanted
vibration during braking, age much like the rear shock mounts. They start to develop small
tears and cracks, then progress to completely broken out of their
mounting. The normal
symptom is vibration in the steering wheel under light
breaking. Ignoring this
will result in uneven tire wear. Larger than stock tires /
wheels amplify the symptoms.
Interior
Door Panels
The covering on the door panels begins to
come loose. Once this
begins, you can either buy replacement panels or experiment with
various gluing methods.
If you re-glue them, you’ll probably become adept at panel
removal & replacement, as well as having a small box of the
plastic trim clips in your
garage.
M42/44 PCV
Valve
The vacuum valve on the 4 cylinder motors
has a higher failure rate than the one on the 6 cylinders. Its
failure causes rough idling and sets the Check Engine
light.
Microfilter
This isn’t a problem area, but something to
be aware of. A
microfilter is installed to filter contaminants out of the cabin
air. The only
questionable part of this decision was its placement. Buried in the dashboard /
console, replacing it requires removal of the glovebox, part of the
air ducting and some electronics. The difficulty of
replacement results in it sometimes being ignored, resulting in
inadequate airflow through the system. Sometimes you may believe
the A/C is failing when it just needs a new filter
Brake Light
Switch
The brake light switch will begin to cause a
“Brake Light Circuit” warning intermittently. This will continue until the
switch is replaced and it is good to replace all 3 bulbs at this
time.
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