Town Car V8-4.6L VIN W (1997)
Piston Ring: Testing and Inspection
INSPECTION
CAUTION: Used piston rings should not be transferred from one piston to another, regardless of mileage or piston ring failure may occur.
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Inspect the piston rings for abnormal wear or damage. Replace if necessary. Replace all rings that are scored, broken, chipped or cracked.
PISTON RING END GAP
1. Insert the piston ring into the cylinder by hand and use the piston to push the piston ring slightly beyond bottom of the piston ring travel area 115
mm (4.5 inches) from cylinder block deck face.
2. Use a feeler gauge to measure the ring opening clearance (end gap).
3. If gap is outside of specifications, use a different ring set.
Nominal
Top Ring: 0.13-0.26 mm (0.005118-0.010236 inch).
Second Ring: 0.30-0.55 mm (0.011811-0.021654 inch).
Oil Ring Rail: 0.15-0.66 mm (0.005910-0.025984 inch).
Service Limit
Top Ring: 0.75 mm (0.029528 inch).
Second Ring: 0.75 mm (0.029528 inch).
Oil Ring Rail: 1.25 mm (0.049213 inch).
PISTON RING-TO-GROOVE CLEARANCE
NOTE: If lower lands have high steps, piston should be replaced.
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Check ring-side clearance of compression rings with Feeler Gauge D81L-4201-A or equivalent inserted between ring and its lower land. Gauge
should slide freely around entire ring circumference without binding. Any wear that occurs will form a step at inner portion of lower land.
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If clearance is greater than service limit, replace piston ring.
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If clearance exceeds service limit, even with a new piston ring, replace piston.
Top Ring: 0.040-0.090 mm (0.001575-0.001610 inch).
Second Ring: 0.030-0.080 mm (0.001181-0.003150 inch).
Service Limit: 0.015 mm (0.000591 inch).
