Engine Testing (In Chassis) (014-008)
B3.9 and B5.9 Series Engines
Section 14 - Engine Testing - Group 14
NOTE: Low compression on a single cylinder can be caused
by an external leak or a leak to a coolant passage. A leak
to a coolant passage of this magnitude will also result in
coolant in the cylinder.
A compression leak to the coolant will normally be detected
by a loss of coolant as the coolant is blown from the cooling
Service Tip: Remove the drive belt from the water pump.
Refer to Procedure 008-002 for removal and installation of
Run the engine for 1 to 2 minutes, and check for coolant
being blown from the radiator by compression gases.
NOTE: The compressed air load in the accompanying il-
lustration must be attached to the air compressor outlet (2).
Make sure the air compressor will be unloaded during the
Apply regulated air pressure of 655 kPa [95 psi] to the air
compressor unloader (1).
Do not crank the engine for more than 30 seconds.
Excessive heat will damage the starting motor.
Crank the engine and observe the oil pressure when the
engine starts. If the engine fails to start within 30 seconds,
allow the starting motor to cool for 2 minutes before crank-
ing the engine again.