Cleaning And Inspection; Cylinder Block And Crankcase Cover - Mercury 40 Service Manual

Cleaning and Inspection

Cylinder Block and Crankcase Cover

IMPORTANT: Crankcase cover and cylinder
block are matched, line-bored assembly should
not be mismatched by using a different crank-
case cover or cylinder block.
Inspect cylinder block and crankcase cover for
cracks or fractures.
Check gasket surfaces for nicks, deep grooves,
cracks and distortions that could cause com-
pression leakages.
Check that all water passages in cylinder block
are not obstructed. Check locating pins in cylin-
der block that they are tight.
Check crankcase cover fuel/bleed passages
that they are not obstructed. Verify that check
valves (2) in crankcase cover and block are not
damaged.
Thoroughly clean cylinder block and crankcase
cover. Verify that all sealant and old gaskets are
removed from matching surfaces. Clean all car-
bon deposits from exhaust ports.
Inspect spark plug holes for stripped or dam-
aged threads.
90-852572R1 JANUARY 1998
CAUTION
If crankcase cover and cylinder block is to be
submerged in a very strong cleaning solution, it
will be necessary to remove the crankcase cover/
cylinder block bleed system from cover/cylinder
block to prevent damage to hoses and check
valves.
CYLINDER BORE SIZE
PISTON SIZE
Standard Diameter
.015 Oversize
.030 Oversize
Inspect cylinder bores for scoring (a transfer of
aluminum from piston to cylinder wall). Cylinder
wall scoring usually can be "cleaned up" by hon-
ing or re-boring.
CAUTION
When re-boring cylinder block, remove hone fre-
quently and check condition of cylinder walls.
DO NOT hone any more than absolutely neces-
sary, as hone can remove cylinder wall material
rapidly.
HONING PROCEDURE
Follow hone manufacture's recommendations for
use of hone cleaning and lubrication during honing.
IMPORTANT: After honing, bores should be thor-
oughly cleaned with hot water and detergent.
Scrub well with stiff bristle brush and rinse with
hot water. If any abrasive material is allowed to
remain in the cylinder bore, it will cause a rapid
wear of new piston rings and cylinder bore. After
cleaning, bores should be swabbed several
times with 2 cycle engine oil and a clean cloth.
Wipe excess oil with clean, dry cloth. Cylinders
should not be cleaned with kerosene or gasoline.
Clean remainder of cylinder block.
Hone all cylinder walls just enough to de-glaze.
CYL. BLOCK
FINISH HONE
2.988 in.
75.895 mm
3.003 in.
76.276 mm
3.018 in.
76.657 mm
POWERHEAD - 4-23