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BMW cooling systems
have been known for being troublesome for quite some time. One of the
principle areas of failure are the thermostat and water pump.
Overheating problems are common on these cars, and if your engine overheats,
you may find yourself having to replace your head gasket, which is not
Begin the process by
gaining access to your thermostat. This requires the removal of the
fan and belts, as well as the removal of all coolant from the system.
See the following technical articles for instructions on how to get to this
With all of your
equipment removed, the front of your engine should resemble
and you should see the black plastic thermostat housing. Remove
screws that attach the housing to the cylinder head. Pull off the
thermostat housing (Figure
2). It may require just a little bit of force to remove if it's
caked on there. The thermostat can be pulled out of the head now (Figure
3 - shows the head removed from the car).
shows the backside of the thermostat.
Install a new
thermostat into the cylinder head using a new o-ring to seal it to the head
The thermostat should fit snuggle into it's bore in the cylinder head.
Make sure that the o-ring is seated properly (Figure
6), and that the small vent hole or arrow faces up. Use a new seal
on the thermostat housing (Figure
7). If your head has been damaged by corrosion and electrolysis (Figure
8), then you may want to add some black silicone sealant to the
thermostat housing when you install it (Figure
Figure 10 shows the thermostat housing remounted with an appropriate
amount of squeeze-out from the black silicone.
shows the thermostat housing reattached to the head, and the flywheel sensor
cable correctly routed around the housing.
Well, there you have it - it's
really not too difficult at all. If you would like to see
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