Cylinder Head, Installing, M52 Engine - BMW 5251 Service Manual

Cylinder Head Removal
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and l n s t a l l a t i ~ i
4
Cylinder head bolt loosening sequence.
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Using BMW special tool 11 2 250 or an equivalent tool, loos-
en cylinder head bolts in sequence. Discard head bolts.
-
Separate the cylinder head from the block and remove head.
Evaluate head as described in 116 Cylinder Head and Val-
vetrain.
Cylinder head, installing, M52 engine
If the camshafts were removed and installed while the cylin-
der head was off, a minimum waiting time is required after in-
stalling the camshafts. When the camshafts are removed, the
hydraulic lifters can expand. This expansion can cause in-
creased valve lift when the camshafts are bolted down, result-
ing in open valves.
Camshaft installation waiting times
68"
F
(20"
C)
and higher
4
minutes
50.68' F (1 0-20" C) 11
minutes
32-50' F (0-1 0" C) 30
minutes
-
Clean cylinder head and gasket surfaces of cylinder block
and all timing chain covers.
CAUTION-
Do not use a metal scraper or wire brush to clean the alumi-
num cylinder head orpistons. If necessary, use a hard wood-
en orplastic scraper. Also available are abrasive discs to be
used in conjunction with an electric drill. Be sure to use the
correct disc for the type of metal being cleaned.
-
Remove all debris and fluids from bolt holes and clean with a
thread chaser.
-
Check gasket surface of cylinder head and cylinder block for
warpage using a straight edge.
NOTE-
If the cylinder head has been machined, a special 0.3 mm
thicker gasket should be installed. The thicker gasket is avail-
able from an authorized BMW dealer.