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Chapter 19 Engine Reassembly and Break-In
Overtightening the valve cover bolts can warp the
cover fl anges, causing oil to leak. Be careful!
Adjusting Crankshaft Endplay
and Installing the Crankcase
Cover
The next step in reassembly is to reinstall
the crankcase cover. Crankshaft endplay should
have been measured before the engine was dis-
assembled. If the endplay was greater or less
than specifi cation, any necessary endplay adjust-
ments must be made before the crankcase cover
is bolted on.
Endplay will vary with engine type, design,
and use. Endplay, along with bearing clearance,
allows room for thermal expansion during engine
operation. See Figure 19-26. For this reason, end-
play must be held to the exact tolerances specifi ed
by the manufacturer.
The method of adjusting endplay varies depend-
ing on engine design. Typically, endplay is adjusted
by installing thicker or thinner gaskets on the
crankcase cover or by installing different thickness
thrust washers on the crankshaft. A thicker gasket
or thrust washer effectively moves the main bear-
ings farther apart, increasing endplay. Installing a
thinner gasket or thrust washer decreases endplay.
Always follow the manufacturer’s instructions for
adjusting endplay.
Caution
Overt O Ov v e ti ghtening e g t h h e valve e c over bolts c an warp th e
cover co o o ve r fl fl anges, ge , causing a a s o o il to leak. Be careful!
O O O t ti h t i t h h l b l t th
When the necessary endplay adjustments are
made, make a fi nal inspection of the engine’s inte-
rior. Make sure that the timing marks are prop-
erly aligned and the oil slinger and governor shaft
and gear are installed. If the power-take-off end is
keyed, put tape over the keyway to protect the oil
seal when the cover is installed. Then, install the
proper gasket on the crankcase cover and insert two
or three bolts through the cover to hold the gasket
in place. Align the cover with the crankcase, slide it
over the crankshaft, and tighten the cover bolts.
Reinstalling External Engine
Components
Next, the fl ywheel can be reinstalled. To reinstall
the fl ywheel, turn crankshaft until the keyway is
in the 12 o’clock position, and then insert the key. If
the shaft uses a Woodruff key, install it as shown in
Figure 19-27. Make sure that the key seats properly in
the keyway before starting the fl ywheel on the shaft.
Next, align the fl ywheel keyway with the
crankshaft key and install the fl ywheel. Install
the starter clutch and crankshaft nut. Tighten the
crankshaft nut to the correct torque.
Use a strap wrench or a spanner wrench to hold the
fl ywheel when torquing the crankshaft nut..
Note
Use U Us a a strap t t p wrench w or a spanner p wrench to hold the
fl fl ywheel y h h l when h n torquing r th e e crankshaft nut
Figure 19-25.
When installing the valve cover bolts, tighten them in the
proper sequence. Tighten to the specifi ed torque to avoid
warping the cover fl anges. (Briggs & Stratton Corp.)
1
4
3
2
Figure 19-26.
Crankshaft bearings and thrust surfaces must have
some clearance (endplay) to provide space for
lubricant and for heat expansion.
Crankshaft
Crankcase
Bearing
clearance
Endplay between
thrust surfaces