Cleaning And Inspection - MerCruiser GM4 Service Manual

! WARNING
Gasoline is extremely flammable and highly ex-
plosive under certain conditions. Be sure electri-
cal source to engine is disconnected. Do not
smoke or allow sources of spark or open flame in
area when installing new pump. Wipe up any
spilled fuel immediately.
6. Disconnect crankcase ventilation hose at rocker
arm cover.
7. Disconnect wires connected to electric choke.
8. Remove exhaust manifold fasteners; remove
manifold assembly and discard gaskets.
9. Remove exhaust elbow.

Cleaning and Inspection

1. Clean gasket material from all surfaces and wash
parts in solvent.
2. Inspect all parts carefully. Machined surfaces
must be clean and free of all marks and deep
scratches, or water and exhaust leaks may result.
3. Check water passages for foreign material. Pas-
sages must be clean for efficient cooling.
4. If more thorough inspection is desired, pipe plugs
may be removed from exhaust manifold and ex-
haust elbow.
IMPORTANT: If plugs are removed, coat threads
with Perfect Seal before reinstalling.
Index
6C -2 - MANIFOLD
IMPORTANT: If manifold to cylinder head studs
have broken, install all new studs with Loctite
8831 AFTER checking head and manifold sur-
faces for warpage. Also use all new manifold at-
taching nuts.
5. Check for cracks.
6. To test manifold body for leaks, block off plates,
plugs or short hoses with plugged ends must be
used. One block off plate must have a threaded
hole for attaching compressed air hose. Use new
gaskets when installing block off plate(s). Apply
40 PSI (276 kPa) of air pressure and submerge
manifold in water. Air bubbles will indicate a leak.
Installation
If exhaust manifold body requires replacement,
transfer all parts (from old manifold) to new manifold
body.
1. Position new gasket on head and install manifold
in position, making sure gasket is in place.
2. Tighten fasteners evenly and torque to 23 lb. ft.
(33 N·m), starting in center and working out to-
ward ends.
IMPORTANT: After engine has been brought up to
operating temperature, allow engine to cool. Re-
torque manifold fasteners.
3. Install carburetor (if removed) and connect crank-
case ventilation hose at rocker arm cover.
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