B3.9 and B5.9 Series Engines
Section 1 - Cylinder Block - Group 01
If the compression is low on one or more nonadjacent
cylinders and the pressure can not be increased by oiling
the rings, poor valve sealing is to be suspected.
Valve leakage is often audible from the intake and/or ex-
The parent valve seats can be reground to a depth of 0.254
mm [0.010 in]. Reground seats are identified with a mark
on the cylinder head. Service valve seats must be installed
in previously ground valve seats.
Head Gasket Sealing
If the compression was found low on adjacent cylinders and
the pressure can not be increased by oiling the rings, the
head gasket is probably leaking between the cylinders.