MULTICYLINDER ENGINES
131
Cylinder block
Core plug Installation tool
Sealing edge
before Installation
Strike here
Wlthh7
Removal
and
Installation
Remove plug
Core
Plug
Replacement
Check the condition
of
all core plugs in the blockwhen-
ever the engine is out
of
the boat for service.
If
any signs
of
leakage or corrosion are found around one core plug,
replace them all. Core plugs in the cylinder block prevent
damage to the block should the coolant freeze. The cylin-
der block
of
2GM, 3GM and 3HM engines is equipped
with cast iron, removable cylinder liners. See
Cylinder
Liners in this chapter.
NOTE
A machine shop can replace core plugs in-
expensively.
If
machine work on the engine
is necessary, have the core plugs replacedat
the same time.
CAUTION
Do not drive core plugs into the engine cast-
ing. It will be impossible to retrieve them
and
they can restrict coolant circulation, re-
sulting in serious engine damage.
1. Tap the bottom edge
of
the core plug with a hammer
and drift. Use several sharp blows to push the bottom
of
the plug inward, tilting the top out (Figure 81).
2. Grip the top
of
the plug firmly with pliers. Pull the plug
from its bore (Figure 82) and discard.
NOTE
It is also possible to remove core plugs by
drilling a hole in the center
of
the
plug
and
prying it out with an appropriate size drift
or pin punch. When removing a large core
plug, the use
of
a universal impact slide
hammer is recommended.
3. Clean the plug bore thoroughly to remove all traces
of
the old sealer. Inspect the bore for any damage that might
interfere with proper sealing
of
the new plug.
4. Coat the inside diameter
of
the plug bore and the outer
diameter
of
the new plug with sealer. Use an oil-resistant
sealer
if
the plug is to be installed in an oil gallery or a wa-
ter-resistant sealer for plugs installed in the water jacket.
5. Install the new core plug with an appropriate size core
plug installation tool (Figure 83), driver or socket. Posi-
tion the outside edge
of
the plug 2-3 mm (0.08-0.12 in.)
inside the block.
6. Repeat Steps 1-5to replace each remaining core plug.
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