Cylinder Bores - Mercury 150 EFI Service Manual

Cylinder Bores

1. Inspect cylinder bores for scoring, scuffing or a transfer of aluminum from piston to cylin-
der wall. Scoring or scuffing, if NOT TOO SEVERE, can normally be removed by honing.
If a transfer of aluminum has occurred, an acidic solution such as "TIDY BOWL CLEAN-
ER" should be applied to the areas of the cylinder bore where transfer of aluminum has
occurred. After the acidic solution has removed the transferred aluminum, thoroughly
flush the cylinder bore(s) to remove any remaining acid. Cylinder walls may now be
honed to remove any glaze and to aid in the seating of new piston rings.
HONING PROCEDURE
a. When cylinders are to be honed, follow the hone manufacturer's recommendations
b. For best results, a continuous flow of honing oil should be pumped into the work
When honing cylinder block, remove hone frequently and check condition of cylin-
der walls. DO NOT hone any more than absolutely necessary, as hone can remove
cylinder wall material rapidly.
c. Start stroking at smallest diameter. Maintain firm stone pressure against cylinder
d. Localize stroking in the smallest diameter until drill speed is constant throughout
e. Thoroughly clean cylinder bores with hot water and detergent. Scrub well with a stiff
2. Hone all cylinder walls just enough to de-glaze walls.
3. Measure cylinder bore diameter (with a snap gauge micrometer) of each cylinder, as
shown below. Check for tapered, out-of-round (egg-shaped) and oversize bore.
90-883728 JULY 2001
for use of the hone and cleaning and lubrication during honing.
area. If pumping oil is not practical, use an oil can. Apply oil generously and frequent-
ly on both stones and work area.
wall to assure fast stock removal and accurate results.
length of bore. Expand stones, as necessary, to compensate for stock removal and
stone wear. Stroke at a rate of 30 complete cycles per minute to produce best
cross-hatch pattern. Use honing oil generously.
bristle brush and rinse thoroughly with hot water. A good cleaning is essential. If any
of the abrasive material is allowed to remain in the cylinder bore, it will cause rapid
wear of new piston rings and cylinder bore in addition to bearings. After cleaning,
bores should be swabbed several times with engine oil and a clean cloth, then wiped
with a clean, dry cloth. Cylinders should not be cleaned with kerosene or gasoline.
Clean remainder of cylinder block to remove excess material spread during honing
operation.
CAUTION
POWERHEAD
51846
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