Mercury MERCRUISER, Service Manual, Page: 21 / 566

Task Interval Maintenance to Be Performed
Every 100 hours or
annually
(whichever occurs first)
• Touch up the paint on the power package.
• Change the engine oil and filter.
• If the condition of the spark plugs, spark plug wires was satisfactory at the initial inspection (as
listed in
Every 300 hours or 3 years
), inspect the condition of these components every year
and replace as necessary.
• Inspect the water‑separating fuel filter and replace if debris is visible.
• Check the crankcase ventilation hoses and inspect the PCV valve, if equipped.
• Inspect the condition and the tension of the belts.
• Check the coolant level and antifreeze concentration for adequate freeze protection. Correct if
necessary. Refer to the
Specifications
section.
• Change the transmission oil and filter where applicable. This should be done once a year or
every 300 hours, whichever comes first.
• Inspect the exhaust system components. If the package was equipped with water shutters
(flapper valves), verify that they are not missing or worn.
Every 300 hours or 3
years
(whichever occurs first)
• Clean the flame arrestor.
• Check the engine mounts for tightness and tighten to specifications if necessary.
• Inspect the condition of the spark plugs, spark plug wires. Replace as necessary. If the
condition of these components is satisfactory at inspection, repeat inspection every 100 hours
or once a year, whichever occurs first.
• Check the electrical system for loose, damaged, or corroded fasteners.
• Check the cooling system and the exhaust system hose clamps for tightness. Inspect both
systems for damage or leaks.
• Disassemble and inspect the seawater pump and replace worn components.
• Clean the seawater section of the closed‑cooling system. Clean, inspect, and test the
pressure cap.
• Replace the vent valve on each exhaust elbow (port and starboard).
Every 5 years
• Replace the coolant/antifreeze. Replace every two years if not using extended‑life coolant/
antifreeze.
Maintenance Schedule—TowSport Models
Routine Maintenance
NOTE: Only perform maintenance that applies to your particular power package.
Task Interval Maintenance To Be Performed
Each day start
• Check the engine oil level. You can extend this interval based on experience with the product.
• Check the transmission fluid level.
Each day end
• If operating in saltwater, brackish water, or polluted water, flush the seawater section of the
cooling system after each use.
Weekly
• Check the water inlets for debris or marine growth.
• Check and clean the seawater strainer, if equipped.
• Check the transmission fluid.
Every two months or 50
hours
• If operating in saltwater, brackish water, or polluted water, apply Corrosion Guard to the
power package.
• Check the battery connections and the fluid level.
• Ensure that the gauges and the wiring connections are secure. Clean the gauges. If operating
in saltwater, reduce this interval to every 25 hours or 30 days, whichever occurs first.
Scheduled Maintenance
NOTE: Only perform maintenance that applies to your particular power package.
Task Interval Maintenance to Be Performed
25 hours
• Change the transmission fluid. Models equipped with a transmission filter must also have the
filter changed at this time.
Maintenance
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 1C-5