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03-G0-24
Engine-Service
03-G0-24
SERVICE PROCEDURES (Continued)
Measure cylinder bore diameter in direction A and B at
32 mm ( 1 .25 inch) below top of cylinder block deck.
CENTERUNE OF
CRANKSHAFT
A - AT RIGHT ANGLE TO CENTER LINE OF ENGINE
B
•
PARALLEL TO CENTER LINE OF ENGINE
A23320.A
The cylinder bore service limit equals the average of
measurements A and B when measured at the center
of the piston travel.
The cylinder bore taper equals the difference between
measurements A at top and bottom of cylinder bore
and A at top and bottom of cylinder bore.
The cylinder bore out-of-round equals the difference
between measurements A and B when measured at
the center of the piston travel.
Refer to Specifications as described in Section
03-Q1 A (3.8L) or Section 03-0 1 8 (4.6L).
On 3.8L engine, measure the piston outer diameter as
described to obtain the specific clearance. It may be
necessary periodically to use another piston (within
the same grade size) that is either slightly larger or
smaller to achieve the specified clearance.
On 4.6L (2V) engine, measure the piston outer
diameter as described to obtain the specific
clearance. Pistons are graded prior to skirt coating.
Exact clearance cannot be determined. Clearance is
calculated based on bore-piston dimensions.
Piston-to-bore clearance with coating is -0.01 2.0.026
mm (-0.00047.0.00 1024 inch).
If the taper, out-of-round and piston-to-cylinder bore
clearance conditions of the cylinder bore are within
specified limits, new piston rings will work well.
H installing new piston rings in a used cylinder that has
not been refinished, remove the cylinder wall glaze
only using spring-loaded Engine Cylinder Hone Set
T73L -60 1 1-A. Remove only if there is no visible sign of
cross-hatch markings on the cylinder walls. (Refer to
Cylinder Block, Cylinder Walls, Refinishing.) Always
clean the cylinder bore thoroughly with detergent and
water solution.
1 . NOTE: After any refinishing operation, allow
cylinder bore to cool. Make sure piston and bore
are clean and dry before piston fit is checked.
Calculate size of piston to be used by taking a
cylinder bore check. Follow procedures
described previously.
2. Select proper size piston to provide desired
clearance. Measure piston diameter in-line with
centerline of piston pin and at 90 degrees to
piston pin axis.
3. Make sure piston and cylinder blocks are at room
temperature, 2 1
oc
(70
°
F)
.
Piston Rings-Fitting
1 . NOTE: Always use a piston ring expanding tool to
install rings on a piston.
Select proper piston ring set for size of cylinder
bore.
2.
CAUTION: Use care when installing piston
ring to avoid possible damage to piston ring
or cylinder bore.
Position piston ring in corresponding cylinder
bore.
3.
Insert piston ring into cylinder bore using a piston.
Push piston ring slightly beyond bottom of ring
travel, 1 1 5 mm (4.5 inches) from cylinder block
deck face.
4.
Verify position of piston ring in bore is square with
cylinder wall and check piston ring end gap as
described.
A15061-A
1 997 Thunderbird. Cougar July 1996