Exhaust Manifold And Exhaust Cover; Cylinder Bore - Mercury 15XD Service Manual

a -

Exhaust Manifold and Exhaust Cover

1. Remove all carbon deposits and gasket material from exhaust manifold and cover.
2. Inspect for grooves, cracks or distortion that could cause leakage. Replace parts as
required.

Cylinder Bore

CHROME BORE - -
ALL MODELS S/N OG202749 AND BELOW
Cylinder bores which are chrome cannot be bored or efficiently honed. Honing a chrome
cylinder bore is not necessary nor is it recommended. Do not mistake cylinder bore poros-
ity (pitting) for cylinder damage. Porosity in a chrome lined cylinder is normal and is not
detrimental to engine operation or performance.
1. If chrome surface is flaking, or if a groove or any other mark penetrates the chrome
surfacing to the aluminum portion of the cylinder wall, the cylinder block must be re-
placed.
2. To determine if a groove or mark on the cylinder wall penetrates the chrome surfacing
to the aluminum cylinder wall, apply a small amount of diluted muriatic acid (TIDY
BOWL CLEANER) to the groove or mark. If the groove or mark begins to " fizz" , the
aluminum wall is exposed and the cylinder block and crankcase cover must be re-
placed.
3. If a piston is scored and transferred aluminum to the cylinder walls, remove the alumi-
num from the wall as follows:
a. Remove all loose aluminum deposits from cylinder walls with a stiff bristle brush.
b. Apply a small amount of diluted muriatic acid (TIDY BOWL CLEANER) onto alumi-
c. Leave the acid solution on the aluminum deposit for 1 to 2 minutes, then wash cyl-
d. Steps " b"and " c"may require repeating several times before all aluminum depos-
e. After cleaning aluminum deposits from cylinder bores, apply light oil to each cylin-
90-826883R2 JUNE 1998
Decompression Ports
num deposits. A" fizzing"action will appear indicating that aluminum is being dis-
solved.
inder thoroughly with hot water and detergent.
its are gone.
der bore with a clean cloth.
POWERHEAD
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