Closed Cooling System; Checking Coolant Level - Mercury MerCruiser MCM 454 Mag MPI Service Manual

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SERVICE MANUAL NUMBER 23

5. Position drive unit so that it is straight back and stop engine. Remove fill cap from pump.

IMPORTANT: Drive unit must be positioned straight back and power steering fluid

must be hot to accurately check fluid level.

6. If fluid is still foamy (in Step 5), repeat Steps 4 and 5 until fluid does not foam and level

Closed Cooling System

Allow engine to cool down before removing pressure cap. Sudden loss of pressure

could cause hot coolant to boil and discharge violently. After engine has cooled,

turn cap 1/4 turn to allow any pressure to escape slowly, then push down and turn

cap all the way off.

1. Coolant level in heat exchanger should be full (to bottom of filler neck).

IMPORTANT: When reinstalling pressure cap, be sure to tighten it until it contacts

stop on filler neck.

2. Coolant level should be between the ADD and FULL marks on coolant recovery

90-861326--1 MARCH 1999

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Allow any foam in pump reservoir to disperse, then check fluid level and add fluid, as

required, to bring level up to FULL HOT mark on dipstick. DO NOT OVERFILL. Reinstall

fill cap securely.

remains constant.

reservoir with the engine at normal operating temperature.

Coolant Recovery Reservoir

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