Construction; General; Cylinder Block; Flywheel Housing - Sisu Diesel 645 Series Workshop Manual

Construction

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CONSTRUCTION

General

645---engine is liquid cooled, 6---cylinder, 4---stroke, in ---line
diesel engine with direct injection. It is designed with wet, re-
placeable, mid support cylinder liners, oil---cooled pistons
and two separate cylinderheads.
The engines have a rigid and ribbed cylinder block. The crank
mechanism is designed for supercharging. The cylinder
liners are wet and supported at the middle. The cylinder head
bolts are high tensile bolts.

Cylinder block

The cylinder block is the main body of the engine, to which
other engine parts are attached. Wet and replaceable cylinder
liners are supported at the middle which reduces vibrations
and directs coolant circulation mainly to the upper part of the
liners.
The seal between the cylinder liner lower part and the cylinder
block is achieved by three o---rings, which are fitted in
grooves in the cylinder block. The upper part is sealed by the
cylinder head gasket.
The camshaft is located in the cylinder block. 645---engines
have separate bearing sleeves in all camshaft bearing loca-
tions. The drilling for the camshaft rear end is covered with a
plug.
There are spaces on both sides of the rear main bearing for
guide bearing shims (the crankshaft thrust bearings).

Flywheel housing

The flywheel housing is fitted at the rear end of the cylinder
block. The seal for the crankshaft rear end is placed in a bore
in the housing. The starter motor fixing point is fitted in the fly-
wheel housing.
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The lower face of the flywheel housing functions as a sealing
surface for the oil sump gasket. This means that the lower
face of the cylinder block must be level with the flywheel
housing. When fitting the flywheel housing, its position is
determined by tension pins.
The flywheel housing are delivered according to the require-
ments set, by the engine application and different flywheel
housings can be mounted on all engine types.