Yanmar 6LY3 series Service Manual page 62

PERIODIC MAINTENANCE
Clean the Engine Oil Cooler
Rust and scale are deposited inside the seawater
system during extended use.
This lowers cooling performance, so it is necessary
to clean and maintain the oil cooler.
Internal contamination of the oil cooler reduces
cooling efficiency and accelerates the oil cooler
degeneration.
1. Remove the oil cooler from the engine.
2. Flush and clean the inside (seawater passages)
of the cooler tubes with a nylon brush.
3. Clean the outside oil passages of the cooler
tubes.
4. When reassembling, install new O-rings and
separator packings.
5. Apply 0.2 MPa (29 psi) of pressure on the oil
passage and inspect for leaks.
Clean the Seawater and Coolant Systems
Rust and scale are deposited inside the seawater
and coolant systems during extended use. This
lowers coolant performance, so it is necessary to
clean and maintain the following parts in addition to
replacing the coolant.
1. Clean and inspect coolant rubber hoses.
• Remove the coolant hoses for the closed
coolant system and the seawater system.
• Check for dirt buildup and other obstructions.
Clean and clear if necessary.
• Check for cracks and deterioration of the
rubber hoses. If necessary, replace.
• Replace the used hose clamps, if necessary.
2. Inspect the heat exchanger and pressure cap.
See Heat Exchanger Components and
Functions on page 7-13.
4-30
Replace the Rubber Fuel Hoses
Rubberized fuel hoses tend to dry out and become
brittle after 2000 hours or 2 years of engine
operation (whichever comes first).
See your authorized Yanmar marine dealer or
distributor to replace the rubber fuel hoses.
Replace the Thermostat
See Thermostat Components and Functions on
page 7-17.
© 2007 Yanmar Marine International
Periodic Maintenance Procedures
6LY3 Service Manual