If the camshaft is being replaced due
to cam lobe wear, it is recommended
that the corresponding lifters should
also be replaced to avoid damaging
the new camshaft.
Hydraulic lifters, checking and
replacing
Modern BMW 6 cylinder engines use
self-adjusting hydraulic lifters to keep
the valve clearances within a limited
working range. (
A
) section view of
camshaft , (
B
) hydraulic lifters are
sealed units and require no
maintenance, (
C
) valve with conical
valve spring.
Under some circumstances, such as a
cold start, the cam followers may
become noisy. Hydraulic lifter noise is
usually a high-pitched tapping or
chattering noise. In most instances,
this is considered normal as long as
the noise goes away in a few minutes
(maximum 20 minutes). If the noise
does not go away, either the lifter is
faulty or the oil pressure to the lifter is
low. Hydraulic lifter replacement
requires that the camshaft first be
removed.
Note:
Before checking hydraulic lifters, make
sure engine oil is fresh and at the
proper level.
-
Run engine until it reaches normal
operating temperature.
Remove microfilter housing:
Remove microfilter for interior
ventilation.
Cylinder Head and Valvetrain
http://ebahn.bentleypublishers.com/BMW/3/E46/Repair%20Manuals/1...
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2/25/2009 9:47 PM