Modifications To The Cylinder Head (32 Valve) - Porsche 928 Workshop Manual

928 Enoine. Cvlinder Head and Valve Drive
15
Modifications to the cylinder head (32 valve)
From Model 89
Engine type M 28.41142
Note
Only the reinforced cylinder heads will be avai-
lable as spare parts for all vehicles from
Model 137 onwards. The unfinished part
number, in the casting, is 928.104.413.2R
1. The cylinder head has been reinforced by
20 mm in the area of the bearing surfaces
for the cylinder head bolts (arrow).
3. New bolt length
M 12 x 199
M 12 x 149
The tightening sequence remains unchanged
1 st stage
20
Nm (15 ft. lb.)
2nd stage
90" torque angle
3rd stage 90" torque angle
Note
If oil and water have been mixed, the cylinder
heads must be subjected to a thorough visual
inspection (hairline cracks). The cooling
system must also be checked for leaks. Use
test unit VW 1274 above the expansion tank
for the leak test (max. 1 bar). The camshaft
covers must be removed for visual inspection.
a
2. The new 20 mm longer hexagon head
bolts must be used for assembly.
a
Modifications to the cylinder head (32 valve)
15 - 116e
Printed in Germany - XXII, 1989