Flushing Engine; Flushing Cooling System - Using Cowl Flush Plug; Flushing Cooling System - Using Flushing Attachment 44357A2 - Mercury 150 EFI Service Manual

MAINTENANCE

Flushing Engine

Flushing Cooling System – Using Cowl Flush Plug
Flush the internal water passages of the outboard with fresh water after each use in salt,
polluted or muddy water. This will help prevent a buildup of deposits from clogging the
internal water passages.
NOTE: Engine can be stopped or running at idle speed when flushing the cooling system.
Do not flush engine using a water system that exceeds 45 psi.
1. Remove the plug from fitting in the bottom cowl.
2. Attach a water hose to the fitting. Turn water on and flush for 3 to 5 minutes.
Flushing Cooling System – Using Flushing Attachment 44357A2
When flushing, verify that area in vicinity of propeller is clear and that no person
is standing nearby – to avoid possible injury. It is recommended to remove pro-
peller as a precautionary measure.
1. Install Quicksilver Flushing Attachment 44357A2 (or equivalent tool) on the gear
housing from the FRONT side, positioning the rubber cups over the water intake
openings.
2. Connect hose [1/2 in. (12.7 mm) I.D. or larger] between flushing attachment and water
tap.
IMPORTANT: To prevent water pump damage, do not start or run engine unless
cooling water is flowing.
3. With the outboard in the normal operating position (vertical), partially open water tap
(IT IS NOT NECESSARY to use full water pressure) and adjust water flow so that
there is a significant water loss around the rubber cups.
4. Start engine and idle in NEUTRAL. Increase engine speed, not to exceed 2500 RPM.
5. Flush or service engine as required. Verify adequate cooling water is provided.
6. Water must be discharged thru "tell tale."
IMPORTANT: Prevent engine overheating. If water flow is insufficient, stop engine
and determine cause before continuing.
7. Flush until discharge water is clear. In saltwater areas, run outboard 3 to 5 min-
8. Stop engine before turning off water.
9. Stop engine, turn water off and remove flushing attachment from gear housing.
IMPORTANT: While and after flushing, keep outboard in upright position until all
water has drained from drive shaft housing to prevent water from entering the pow-
erhead via drive shaft housing and exhaust ports.
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WARNING
90-883728 JULY 2001