Onan MJA Series Service Manual page 76

74
CYLINDER HEADS AND VALVES
less than 10 psi difference between the highest and lowest cylinder,
taken at the same cranking rpm. Excessively high readings indicate
carboned combustion chambers.
Compression readings will deviate considerably from the above read ­
because of differences in. cranking speed. altitude and ambient
temperature conditions. Therefore the specification is given only as
a
. The best indication of leakage is the pressure difference
between cylinders or a compression increase when oil is added to the
cylinder.
3.7.3 DISASSEMBLY - NOTE: Valves, tappets, rocker arms and
pushrods should be kept in order and returned in same order.
1. Drain the engine coolant.
ADJUST VALVE CLEARANCE::::: 'j
HERE
VALVE
SPRING RETA!NER--''''
VALVE
SPRING~1::!
r ­
,~J.'~rr./
""':
ljVALVE SEAT
FIG 3.7. C - CROSS SECTION, VALVE ASSEMBLY