Mercury 225 EFI, Service Manual

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POWERHEAD
Page 4A-48 90-884294 OCTOBER 2001
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 containing muriatic acid (i.e.
“TIDY BOWL CLEANER”) 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
for use of the hone and cleaning and lubrication during honing.
b. For best results, a continuous flow of honing oil should be pumped into the work
area. If pumping oil is not practical, use an oil can. Apply oil generously and frequent-
ly on both stones and work area.
CAUTION
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
wall to assure fast stock removal and accurate results.
d. Localize stroking in the smallest diameter until drill speed is constant throughout
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.
e. Thoroughly clean cylinder bores with hot water and detergent. Scrub well with a stiff
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.
2. Hone all cylinder walls just enough to de-glaze walls.