855523 Mercruiser COVER

This engine uses high voltage to control the fuel injectors.Disconnect electronic fuel injector enable circuit connector to prevent personal injury.Do not come in contact with the fuel injector terminals while the engine is running.
Failure to follow the recommended procedure or the specified tooling that is required for the procedure could result in damage to components.To avoid component damage, follow the recommended procedure using the recommended tools.
The engine valve lash and the injector lash must be within specifications prior to adjusting the compression brake's slave piston lash. Refer to Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust" for the correct procedure for inspection of the engine valve lash. Refer to Testing and Adjusting, "Electronic Unit Injector - Adjust" for the proper procedure for inspection of the injector lash adjustment.Note: The slave piston lash adjustment must be performed while the engine is cold. If the engine is warm, allow the engine to cool prior to performing the following adjustments.Use the following procedure to adjust the slave piston lash on cylinders 1, 3, and 5:Put the No. 1 piston at the top center position on the compression stroke. See Testing and Adjusting, "Finding Top Center Position for No. 1 Piston" for further details.
Illustration 1 g00596577
Typical configuration for the engine compression brake (1) Slave piston adjusting screw (2) Slave piston (3) Rocker arm
Prior to adjusting the lash setting for the engine compression brake, check the identification plate that is on the compression brake's casting in order to determine the model that is installed on your engine. You must have this model number and the engine's serial number prefix in order to determine the lash setting for your engine.
Table 1
Slave Piston Lash Setting
Jake Brake Compression Brakes    
Serial Number Prefix and Model Number (1)    Horsepower Rating    Slave Piston Lash Setting    
BNT1-UP
Jake Brake 340C     Less than 435 hp    
0.94 0.08 mm (0.037 0.003 inch)    
435 hp or more
0.84 0.08 mm (0.033 0.003 inch)    
9AP1-UP
Jake Brake 340C     All ratings    
0.94 0.08 mm (0.037 0.003 inch)    
BET1-UP
7RC1-UP
Jake Brake 340C     All ratings    
0.84 0.08 mm (0.033 0.003 inch)    
BET1-UP
BNT1-UP
9AR1-UP
7RC1-UP
Jake Brake 340D     All ratings    
0.64 0.08 mm (0.025 0.003 inch)    
( 1 ) Check the identification plate that is on the compression brake's casting in order to determine the model that is installed on your engine.Use this procedure for 340C Compression Brakes:
Loosen adjustment locknut (1) and back out the adjusting screw until the slave piston is not in contact with the exhaust valve rocker arm.
Insert the appropriate feeler gauge between the foot of the slave piston (2) and the rocker arm (3). Refer to Table 1 for the correct slave piston lash setting.
Turn the slave piston adjusting screw in a clockwise direction until the slave piston tightens against the feeler gauge. Tighten the adjusting screw for one additional turn in the clockwise direction. The valve spring should start to compress. Allow the oil to be purged from the autolash assembly of the compression brake for 30 seconds.Note: All of the oil must be allowed to drain from the compression brake's autolash assembly. If the temperature of the oil is below 16 °C (60 °F), allow the oil to be purged for an additional two minutes. Serious engine damage may occur if the oil is not properly purged from the autolash assembly.
Slowly turn the adjusting screw counterclockwise until the slave piston begins to loosen against the feeler gauge. A slight drag should be felt on the feeler gauge when the adjustment is correct.Note: Do not overshoot the setting of the slave piston during adjustment. If you overshoot the setting, you must repeat this procedure.
Tighten the adjustment locknut (1) to a torque of 34 5 N m (25 4 lb ft). Recheck the adjustment after tightening the locknut. If necessary, repeat the procedure.Adjust the slave piston lash settings for cylinders 3 and 5 prior to rotating the engine.After you adjust cylinders 1, 3, and 5, reset the timing pin and turn the flywheel for 360 degrees in the direction of the engine's rotation. This will position the No. 6 piston at the top center on the compression stroke. Ensure that the timing pin has located the timing hole that is in the flywheel.Continue to perform the adjustment procedure for the slave piston lash settings on cylinders 2, 4, and 6.Remove the timing pin from the flywheel after all adjustments have been performed. Reinstall the timing cover.Use this procedure for 340D Compression Brakes:
Loosen adjustment locknut (1) and back out the adjusting screw until the slave piston is not in contact with the exhaust valve rocker arm.
Insert the appropriate feeler gauge between the foot of the slave piston (2) and the rocker arm (3). Refer to Table 1 for the correct slave piston lash setting.
Turn the slave piston adjusting screw in a clockwise direction until the slave piston tightens against the feeler gauge. A slight drag should be felt on the feeler gauge.
Tighten the adjustment locknut (1) to a torque of 34 5 N m (25 4 lb ft). Recheck the adjustment after you tighten the locknut. If necessary, repeat this procedure.After you adjust cylinders 1, 3, and 5, reset the timing pin and turn the flywheel for 360 degrees in the direction of the engine's rotation. This will position the No. 6 piston at the top center on the compression stroke. Ensure that the timing pin has located the timing hole that is in the flywheel.Continue to perform the adjustment procedure for the slave piston lash settings on cylinders 2, 4, and 6.Remove the timing pin from the flywheel after all adjustments have been performed. Reinstall the timing cover.