Mercury 305 CID, Service Manual, Page: 752 / 967

SEAWATER COOLING MODELS - 6A-7 90-823225--1 1096
5. Repeat test four times to check repeatability of
results.
Alpha Stern Drive Pump Output
for 15 Second Period
Drive Unit Gear Ratio
Minimum Quantity
U.S. Qts. (L)
1.98:1 3.0 (2.8)
1.84:1 3.3 (3.1)
1.65:1 3.6 (3.4)
1.50:1 4.0 (3.8)
1.32:1 4.5 (4.3)
Stern Drive Unit Seawater
Pickup Pump Repairs
NOTICE
MCM (Stern Drive) Models equipped with
Alpha Drive Units have a seawater pickup
pump mounted in stern drive unit. Refer to
appropriate Stern Drive Service Manual for
further testing and repairs.
Water Circulating Pump
Replacement
Removal
1. Drain water from cylinder block. Refer to “Drain-
ing Seawater Cooling System” as outlined later in
this section.
2. Loosen circulating pump pulley attaching bolts.
Do not remove bolts at this time.
3. Loosen power steering pump brace and pump
mounting bolts, then pivot pump inward and re-
move drive belts.
4. Loosen alternator brace attaching bolts and alter-
nator mounting bolt, then pivot alternator inward
and remove drive belt.
5. Remove pump pulley attaching bolts, lockwash-
ers, clamping ring (if so equipped) and pulley.
6. Disconnect hose(s) from pump.
7. Remove bolts, which secure pump to cylinder
block, and remove pump and old gaskets (dis-
card gaskets).
Cleaning and Inspection
1. Clean gasket surfaces on water pump and cylin-
der block.
2. Inspect water pump for blockage, cracks, sand
holes, corrosion or other damage. Inspect pump
impeller for cracks and erosion. Replace com-
plete pump if any damage exists.
3. Check impeller shaft and bearings for excessive
side play. If play can be felt, replace complete
pump.
4. Inspect pump pulley for bends, cracks, corrosion
or other physical damage. Inspect pulley for rota-
tional trueness. Replace pulley if damaged or un-
true.
Installation
1. Coat both sides of new circulating pump gasket
with Quicksilver Perfect Seal, then position gas-
kets and circulating pump on cylinder block. Coat
threads of circulating pump attaching bolts with
Quicksilver Perfect Seal and install bolts and al-
ternator brace (if applicable). Torque bolts to
specifications.
2. Reconnect hoses to pump.
3. Install pump pulley and clamping ring (if used) on
pump hub and secure with bolts and lockwash-
ers. Tighten bolts securely.
4. Install drive belts and adjust tension as outlined
in “Drive Belt Tension Adjustment.”
5. Start engine and check for leaks.