Mercury 350 MAG MPI Horizon, Service Manual

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53
CH49
Flushing Cooling System – 350 MAG MPI Only
NOTE: Flushing is needed only for saltwater applications. Flushing is recommended after each outing for best
results.
CAUTION
Do NOT start engine at any point in this procedure. If boat is in the water, starting engine during this
procedure will pull in seawater. If boat is out of the water, starting engine may damage the seawater
pump.
IMPORTANT: Do not use this method on boats equipped with waterlift exhaust collectors or mufflers.
1
Remove blue drain plug from the 90
°
elbows located on the bottom of both exhaust manifolds.
2
Remove blue cap from flush socket.
3
Attach quick connect to a water hose.
4
Turn on the water hose.
5
Snap the quick connect and the water hose into the flush socket on the engine.
IMPORTANT: Run bilge pump during flushing to pump flushing water overboard.
6
Flush engine for 10 minutes.
7
Disconnect the quick connect and water hose from the flush socket on the engine by pressing the release
button on the flush socket.
8
Reinstall both drain plugs into the 90
°
elbows located on the bottom of both exhaust manifolds.
9
Reconnect the quick connect and hose into the flush socket on the engine and let flushing water run for a
maximum of 15 seconds. This amount of flushing water is used to fill exhaust manifolds and flush the exhaust
elbows.
CAUTION
Do not let water run more than 15 seconds or too much flushing water will collect in the muffler.
10
Disconnect the quick connect and water hose from the flush socket on the engine.
11
Attach to next engine, if equipped, and repeat procedure.
12
Turn off water.
13
Remove quick connect from the water hose.
14
Replace blue cap into the flush socket on the engine.