Yanmar 4BY - Tests and Adjustments; Pressure Testing Cooling System and Filler Cap

COOLING SYSTEM
7-8
BY Service Manual
Tests and Adjustments
TESTS AND ADJUSTMENTS
Pressure Testing Cooling System
and Filler Cap
Cooling System
Use a cooling system tester with connections
compatible with the Yanmar BY series cooling
system.
1. Remove the filler cap from the heat exchanger.
2. Check that the lugs and sealing flange on the
filler pipe are undamaged and free from
anything that might prevent a good seal.
Figure 7-2
3. Install the tester and adapter in place of the
filler cap.
4. Pump until pressure is 1.45 bar (21 psi)
(Figure 7-2).
5. Pressure should hold steady. If the pressure
drops, there is leakage in the system. Start by
checking all hoses and pipe connections.
A DANGER
SCALD HAZARD!
• NEVER remove the coolant filler cap if
the engine is hot. Steam and hot
engine coolant will escape and
seriously burn you. Allow the engine
to cool before attempting to remove
the filler cap.
• Securely tighten the filler cap after
checking the coolant level. Steam can
escape during engine operation if the
cap is loose.
• Failure to comply will result in death or
serious injury.
0000002enMarine
0003702