Each exhaust manifold assembly
incorporates a catalytic converter. The
converters are mounted close to the
engine for faster heat up. Pre- and
post-catalyst oxygen sensors are a
mounted in each exhaust manifold.
Cooling system
The cooling system circulation is
designed so that coolant flows directly
from the coolant pump to the cylinder
head. The coolant is fed from the coolant
pump through a cast coolant feed
passage to the rear of the cylinder head.
From there it flows forward to the
thermostat housing, radiator and heater
valve.
The coolant passages in the cylinder
block are only connected to the coolant
supply through the holes in the head
gasket. A reduced volume of the coolant
flows through the cylinder block.
All models are equipped with a
DME-controlled electric cooling fan. On
some models, a supplemental cooling
fan is used. See
170 Radiator and
Cooling System
for specific configuration
and application information.
An electrically heated thermostat
controls the flow of coolant through the
radiator based on coolant and outside
temperature, engine load, and driving
speed, rather than just coolant
temperature.
The DME-controlled heated thermostat
Engine-General
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Summary of Contents for 1999-2005 M3
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