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some projects that seem like they should be relatively routineand are very
easy to perform on other carsbut are a huge pain on the BMW 3 Series cars.
Replacing the starter is one of them. Most other cars Ive worked on have
had relatively accessible starters. If you are quick with the tools, you can
have the starter replaced within 15 minutes on some engines. Not so with the
3 Series. The only way to replace the starter is to remove the intake
manifold (Project 12) or remove the transmission (Project 43).
The first and most critical step in the removal process
is to disconnect the battery from the car (Photo 1). This is very important,
as live current is connected to the starter at all times. You can seriously
injure yourself and damage your electrical system if you accidentally ground
the large red wire connected to the starter.
To disconnect the battery, disconnect the negative, or
ground lead from the battery. Always disconnect the negative or ground lead
firstif you disconnect the positive/hot lead, there is a chance that your
tool may touch the metal chassis. This could result in a short circuit,
which would not bode well for you. The worst-case scenario might be if your
wrench hit the chassis and was instantly welded there by the current, then
the battery overheated and exploded because you couldnt break the
connection. In other words, dont risk itbe sure to disconnect the ground
If your car has the original radio in it, be aware you
will need the radio code if you disconnect the battery. The BMW dealer can
look this up for you if you dont have it, but that can be a huge pain, and
most dealers will charge you for the service. Disconnecting the battery may
also erase fault codes stored in your DME. To be on the safe side, I
recommend you read your fuel injection fault codes prior to disconnecting
the battery (see Projects 28 and 29).
Youll need to remove either the manifold or
transmission to access the starter. Once you have the manifold or
transmission removed, the actual process of replacing the starter is not too
difficult. Verify again that the battery is disconnected, and then unbolt
the large, thick red wire harness that connects to the starter. Also
disconnect the much smaller wire harness that plugs into the terminals on
the back of the starter solenoid.
The starter is attached to the transmission case with
two Torx bolts. Remove these bolts (see Project 43), and you should be able
to lift the starter out of the engine compartment (if you removed the
manifold first), or out the back of the engine (if the transmission was
removed). Verify that your old starter looks the same as the new starter and
has the same number of electrical connections on the back.
As indicated in Project 43, the nuts that hold the
starter in place may be very difficult to hold when tightening up the bolts.
This is definitely a job made easier with an assistant on hand. Have your
assistant hold the nuts in the engine compartment while you tighten the
bolts from underneath.
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The battery is located
in the engine compartment on E30 cars, and in the rear trunk on E36 cars.
Shown in this photo is a special BMW battery designed for the convertible
(its larger and intended to withstand increased vibration). Always
disconnect the black negative, or ground, connection first (green arrow).
If you are not planning to remove the battery, this connection is all you
need to disconnectthere is no need to disconnect the positive/hot lead to
the battery. When you disconnect the ground from the battery, make sure
you place or tape the ground lead aside. You dont want it accidentally
falling on the terminal of the battery while youre working and
accidentally connecting up the battery again. A handy device I like to
install on all my cars is a battery cutoff switch (lower inset).
Installation of this switch on the battery ground allows you to remove the
green knob and shut off all power to the car. An added tip: Connect a
small inline fuse from one end to the other, and a small amount of current
will continue to flow, keeping your radio presets from being cleared out
when the battery is disconnected. The E30 battery is shown in the upper