Cleaning The Seawater Strainer, If Equipped; Coolant; Coolant Recommendations - Mercury MerCruiser Service Manual

Models with Closed Cooling

Cleaning the Seawater Strainer, if Equipped

An open seawater strainer or seacock during some service or maintenance procedures can introduce water into the boat,
causing damage or sinking the boat. Always close the water supply from the seawater pump, water inlet, or seacock when
performing service or maintenance on the cooling system.
1. With the engine off, close the seacock, if equipped, or remove and plug the seawater inlet hose.
2. Remove the screws, washers, and cover.
3. Remove the strainer, drain plug, and sealing washer.
4. Clean all the debris from the strainer housing. Flush both the strainer and housing with clean water.
5. Check the cover gasket and replace when damaged or if it leaks.
6. Reinstall the strainer, drain plug, and sealing washer.
Seawater leaking from the seawater strainer could cause excess water in the bilge, damaging the engine or causing the boat
to sink. Do not overtighten the cover screws, or the cover may warp and introduce seawater into the bilge.
7. Install the seal and cover using the screws and washers. Do not overtighten the cover screws.
b
f
c
8. Open the seacock, if equipped, or remove the plug and reconnect the seawater inlet hose.
9. Upon first starting the engine, check for leaks or air in the system that would indicate an external leak.

Coolant

Coolant Recommendations

IMPORTANT: Alcohol‑based or Methanol‑based antifreeze or plain water are not recommended for use in the closed‑cooling
section of the cooling system at any time.
NOTE: All factory installed closed‑cooling systems come filled with Extended Life Coolant. This antifreeze requires draining and
replacing every five years or 1000 hours of operation, whichever comes first. For best results any top‑off fluid used should be
Extended Life Coolant. If Extended Life Coolant is unavailable, any type of ethylene glycol based antifreeze may be used, but it
will require the draining and replacing of the coolant every two years or 400 hours of operation, whichever comes first.
In areas where the possibility of freezing does not exist, it is permissible to use a solution of rust inhibitor and water (mixed to
manufacturer's recommendations).
Page 6C-10
NOTICE
CAUTION
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a
a - Screws and washers
b - Cover with glass
c - Strainer
d - Housing
e - Drain plug and sealing washer
f - Seal
d
e
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© 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015