881677 Mercruiser VALVE, Intake

Illustration 1 g01194649
Manual Barring Group
(1) Gear
(2) Shaft
(3) Knob
(4) Stem
(5) Slot
Illustration 2 g01194658
Manual Barring Group
(5) Slot
(6) Spacer
(7) GuideThe manual barring group provides a means of slowly turning the flywheel to perform service work on the engine.Note: Prelube the engine as you rotate the crankshaft during the normal maintenance operations. Refer to the Testing And Adjusting Section of this manual.A 3/4 inch hex drive on the end of shaft (2) is used to turn gear (1). Guide (7) must be loosened before the shaft is engaged or the shaft is turned.Shaft (2) is spring loaded. The shaft must be pushed toward the flywheel to engage gear (1) in the flywheel ring gear.The shaft can be engaged in position against the flywheel by pushing in on knob (3). Stem (4) engages in slot (5) of shaft (2). When the knob is pushed inward, the O-ring seals shut off the pressure air source (signal to the relay valve) to the starting motor. The loss of air pressure will prevent the start-up of the engine.The barring group can be used to prevent the rotation of the crankshaft. The inside spacer (6) is splined. Shaft (2) and the flywheel will be locked in position when the manual barring group is engaged and guide (7) is tightened according to the torque that is listed in the engine's Specifications manual.When the manual barring group is not active, this component must be disengaged from the flywheel. Lock this component in position. Tighten the guide to the torque that is listed in the engine's Specifications manual.Manual Barring Group (50:1)
Illustration 3 g01194661
Manual Barring Group (50:1 reduction)
(1) Shaft
(2) Locking nut
(3) Adapter
(4) KnobAn electric wrench or an air wrench may be used with the manual barring group to turn the engine slowly. The manual barring group is used while service work is being performed.Use the following procedure to engage the manual barring group:
Loosen locking nut (2).
Pull knob (4) outward while pressing inward on locking nut (2) until the nut is flush with the housing. The nut is part of the pinion shaft which is spring loaded.
Release knob (4) and slowly remove hand pressure from locking nut (2) until the knob engages in the slot of the pinion shaft.Note: If locking nut (2) cannot be flush with the housing, the shaft gear is not meshed with the flywheel ring gear. Maintain inward pressure on the nut while adapter (3) is carefully adjusted. Adjustment of the adapter is achieved by turning the adapter. The adjustment may require the adapter to be turned more than one revolution in either direction. Adjust the adapter until locking nut (2) can be flush with the housing.When the manual barring group is in the engaged position, the engine starting system is disabled.To turn the engine crankshaft, use adapter (3). To operate the manual barring group, use an electric tool or an air tool. The tool must be capable of producing the required torque. The engine will turn one revolution in less than 3 minutes if the speed of the tool is 700 rpm. Any power tool that is used to operate the manual barring group should be equipped with a cushion clutch to prevent damage to the gears.
Do not use an impact wrench to operate the barring device. The use of an impact wrench will cause gear tooth failure.
The engine crankshaft is locked in place when the pinion gear on shaft (1) is engaged with the flywheel ring gear.Use the following procedure to disengage the manual barring group:
Pull knob (4) outward while pressing inward on locking nut (2) until the spring on shaft (1) moves the pinion to the disengaged position.
Check that the pinion gear is fully disengaged.Note: The pinion gear is fully disengaged when locking nut (2) passes by the housing.
Release knob (4).
Tighten locking nut (2) according to the torque that is listed in the engine's Specifications manual.Note: If shaft (1) fails to fully return to the disengaged position, rotate the adapter in either direction. Rotating the adapter in either direction reduces the side loading (friction) between the pinion gear and the flywheel ring gear.
Do not operate the engine starting motor until the barring group pinion gear is fully disengaged from the flywheel ring gear. Serious damage to the engine could result.
When the manual barring group is not activated, the manual barring group must be disengaged from the flywheel and the manual barring group must be secured in the disengaged position.