John Deere stx38 - Manual (Page 78)

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4/23/97
REPAIR ENGINE
PISTON ASSEMBLY
IMPORTANT: Side of ring marked TOP faces top of
piston with Dykem stripe to left of end gap. Top
compression ring has a blue Dykem stripe.
Bottom compression ring has a pink Dykem
stripe.
1. Install rings as shown on piston using ring
expander.
• Compression ring gaps should be staggered 120°.
• Note shape of compression rings and install as
shown.
• Compression rings should be installed with “Pip”
mark up and Dykem strip to left of ring gap.
• Install oil ring spacer first. Make sure that its ends
do not overlap.
• Stagger end gasp of oil rails 180° apart.
• Rings should turn freely in grooves.
NOTE: Install piston pin before retaining ring to
prevent possible scoring of bore.
IMPORTANT: Retaining rings (B) should be
installed with end gap (A) pointing up.
2. Install one piston pin retaining ring (B) in groove of
piston bore (E).
3. Install pin (C) through piston bore (E) and
connecting rod (D). Pin should install easily with
thumb pressure.
4. Install remaining retaining ring (B) in opposite side.
INSTALL PISTON ASSEMBLY
1. Install piston rings so piston ring end gaps are
staggered 120° apart.
2. Compress rings with ring compressor tool.
3. Coat cylinder, piston skirt, rod, and cap bearing
surfaces with oil.
4. Install piston with FLY mark (A) toward flywheel
side of crankcase. Use wooden dowel to push
piston into bore.
Oil Spacer
Oil Rails
Center Compression
Ring
Top Compression Ring
Piston
Ring Gap
“Pip” Mark
Dykem
Stripe
M55898
M5879
B
D
A
C
E
A
M55871