COOLANT SYSTEM
Heat Exchanger Components and Functions
7-14
6LY3 Service Manual
© 2007 Yanmar Marine International
Inspecting the Heat Exchanger
Inspecting the Coolant Tubes
1. Inspect the inside of the tubes for rust or scale
buildup from seawater and clean with a wire
brush
(Figure 7-12)
.
NOTICE: Disassemble and wash when the
coolant temperature reaches 85°C.
Figure 7-12
Figure 7-12
2. Check the joints at both ends of the tubes for
looseness or damage. Repair if loose. Replace
if damaged or corroded.
3. Check the tubes and replace if leaking.
4. Clean any scale or rust from the outside of the
tubes. When cleaning the inside of the tubes,
use a nylon brush which fits inside the tubes.
Inspecting the Cooler Body
1. Check the heat exchanger body and the end
covers for dirt and corrosion. Replace if
excessively corroded or cracked.
2. Inspect the seawater and coolant inlets and
outlets, retighten any joints as necessary and
clean the insides of the hoses and lines.
Heat Exchanger Body Leakage Test
Perform a leakage test on the heat exchanger.
Fit rubber covers on the inlets and outlets of the
heat exchanger. Submerge the heat exchanger in
water. Pressurize the tank to the listed pressure
and check for leaks.
Figure 7-13
Figure 7-13
1 – Filler Cap
2 – Air Hose
3 – Pressure Gauge
4 – Coolant Tank
5 – Rubber Plug
6 – Heat Exchanger Body
7 – Rubber Plug
Pressure Cap Operation
The pressure cap, installed on the coolant filler
neck, incorporates a pressure control valve. The
cap is installed on the filler neck by placing it on the
locking tab and rotating. The top seal of the cap
seals the top of the filler neck and the pressure
valve
(Figure 7-14, (3))
seals the locking seat.
The pressure valve and vacuum valve
(Figure 7-15, (2))
both seal when the pressure in
the coolant system is within the specified value of
0.11 MPa (16 psi). This seals the coolant system.
0006211
Test Pressure
0.2 MPa (29 psi)
0006212
(6)
(7)
(5)
(4)
(
3
)
(2)
(1)
