[click to enlarge]
The BMW 3-Series cars have a hydraulic clutch engagement system - there are
no cables involved with the actuation of the clutch. Although this
actually creates a more reliable clutch system over time, there can be a
failure or break-down of the system if the slave or master cylinder get old
and begin to leak or fail. A spongy feel to the clutch pedal, grinding
of gears when shifting, long pedal travel, and hydraulic leaks under the car
are all signs that one or more components of the system have failed.
The first place I like to start is the clutch slave cylinder, as it is easy
and inexpensive to replace.
Replacement of the slave cylinder is a snap. Its location is easy to
get to from underneath the car. The slave cylinder is located on the
left side of the transmission (Figure
1). Two nuts fasten it to the transmission. First,
disconnect the hydraulic line from the cylinder. Make sure you use a
flare-nut wrench to remove the hose. These hydraulic fittings have a
tendency to strip if you don't use the proper tool. Also, inspect the
clutch slave line - you might want to replace it if it's bulging, or shows
signs of cracking in the rubber. Before you disconnect the line, make
sure that you have a drip pan to catch the fluid that will leak out.
Now, remove the two
nuts that hold the cylinder to the transmission. The slave cylinder
should remove easily. Install the new one and reattach the clutch
The system now needs to be bled. I like to use the
Motive Products Power Bleeder for this task (Figure
2). For more information on using the Power Bleeder, see the
Pelican Technical Article on Bleeding BMW Brakes. Attach the power
bleeder to the top of the master cylinder reservoir (Figure
3) and pump up the pressure in the bleeder. Move to underneath the
car and attach your bleeder hose to the bleed nipple on the slave cylinder (Figure
4). Let the system bleed out until no more bubbles appear.
When finished, remove
the bleeder system, lower the car, and try the clutch again. The pedal
should have a good feel to it, and the clutch should engage normally.
If you are still having problems, you should try replacing your clutch
master cylinder next (tech article coming soon).
Well, there you have it - it's
really not too difficult at all. If you would like to see
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