Fleetwood V8-252 4.1L VIN 8 FI (1983)
Piston: Service and Repair
Piston Knocking Noise Correction
Fig. 12 Measuring piston diameter
When measuring piston diameter, place micrometer 3/16 inch below cross slot or 3/8 inch below oil ring groove, Fig. 12. Cylinder liner diameter is
measured by placing a micrometer two inches down from top of liner and perpendicular to cylinder center line. The difference between the two readings
should be .0010---.0018 inch. Cylinder bore out-of-round should not exceed .0008 inch and piston bore taper should not exceed .0005---.002 inch. If any
reading is not as specified, piston and cylinder liner assembly must be replaced. No attempt should be made to rebore or hone cylinder liners. Refer to
"Cylinder Liner, Replace" for procedure.
Fig. 13 Off centered piston pin. V8-250
On some 1982-85 V8-250 engines a minor to severe internal metallic knock may be encountered. This may be caused by close piston to counterbalance
tolerance on cylinder Nos. 1, 2, 3, 6, 7 and 8 and is usually heard when engine is at operating temperature between 800---1400 RPM.
Caution: Before proceeding be sure to consult applicable Technical Service Bulletins.
The following procedure should be used to correct this problem:
1.
Remove engine oil pan and cylinder heads as previously described.
2.
Inspect all pistons for correct installation.
3.
Using a wax pencil, mark right and left sides of outboard piston skirts which rotate next to crankshaft counterbalance weights on piston Nos. 1, 2,
3, 6, 7 and 8.
4.
Remove and inspect all pistons for off-centered piston wrist pins, Fig. 13. If off-centered piston pins are encountered, replace piston and liner
assembly.
5.
Using a suitable file, remove a small amount of material from piston skirt edges marked in step 3. All surfaces must be smooth and free of all file
marks after reworking. If interference marks are evident in the piston skirts and filing does not remove marks, replace piston and liner assembly.
