COOLANT SYSTEM
Heat Exchanger Components and Functions
12/05
6LY3 Service Manual
7-15
© 2007 Yanmar Marine International
Pressure Valve Operation
Figure 7-14
Figure 7-14
1 – Pressure Valve Spring
2 – Overflow Tube
3 – Pressure Valve
Vacuum Valve Operation
Figure 7-15
Figure 7-15
1 – Vacuum Valve Spring
2 – Vacuum Valve
When the pressure within the coolant system
exceeds the specified value, the pressure valve
opens and steam is discharged through the
overflow pipe into the coolant recovery tank. When
the coolant cools and the pressure drops below the
normal value, atmospheric pressure opens the
vacuum valve and air is drawn in through the
overflow pipe.
The coolant recovery tank keeps the coolant level
from dropping due to discharge of steam when the
pressure valve opens.
NOTICE: The pressure cap for the 6LY3 is different
from the caps for the 6LYA and L6LY2A. The
pressure value 1.1 is punched on the top of the cap
for 6LY3 as shown in Figure 7-16
.
Figure 7-16
Figure 7-16
1 – Pressure Valve Identification
Inspecting the Pressure Cap
WARNING! NEVER open the pressure cap while
the engine is running or right after shutting
down because high temperature steam will be
blown out. Remove the cap only after the
coolant has had a chance to cool down.
1. Remove scale and rust, check the seat and
seat valve, etc. for scratches or wear and the
spring for corrosion or settling. Replace if
necessary.
NOTICE: Clean the pressure cap with fresh
water.
2. Fit the adapter of the tester to the pressure cap
(Figure 7-17)
.
Figure 7-17
Figure 7-17
3. Pump the tester until the pressure gauge is
within the specified pressure range 93 to
123 kPa (13 to 18 psi) and note the gauge
reading. The cap is normal if the pressure holds
for 6 seconds. If the pressure does not rise, or
drops immediately, inspect the cap and repair
or replace as necessary.
Pressure Cap Specifications
Pressure Valve
Open at 93-123 kPa (13-18 psi)
Vacuum Valve
Open at 5 kPa (0.7 psi) or below
0006
3
4
8
(2)
(
3
)
(1)
0006
3
49
(1)
(2)
0006214
(1)
0006215
