Cooling System - Air or Combustion Gas Test (008-019)
B3.9 and B5.9 Series Engines
Section 8 - Cooling System - Group 08
Disconnect the coolant supply and the return tubes from
the air compressor. Use a short piece of hose to connect
the tubes together to prevent coolant loss during engine
Repeat the test for air in the cooling system as previously
described in Procedure 008-019. If no air is found in the
cooling system with the air compressor isolated, repair or
replace the air compressor. Refer to Procedure 012-014.
Use combustion gas leak test kit, Part No. 3822985, or
equivalent, to test for combustion gases in the cooling
It is recommended that the cooling system contain a mix-
ture of 50-percent antifreeze and 50-percent water during
the combustion gas leak test. The use of water only can
result in a color change in the test fluid from blue to tur-
quoise or light green during the test. This is not an indi-
cation of a combustion gas leak.
Drain the coolant level down approximately 50 mm [2 in]
below the radiator cap seal ledge in the radiator fill neck.