Engine - Piston Replacement

Classification:
EM00-006

Reference:
NTB00-049

Date:
June 5, 2000

1996-2000 PATHFINDER, 1999-2000 FRONTIER & QUEST, & 2000 XTERRA; VG33E PISTON REPLACEMENT

APPLIED VEHICLE(S):
1996-2000 Pathfinder (R50)
1999-2000 Frontier (D22)
1999-2000 Quest (V41)
2000 Xterra (WD22)

APPLIED DATE(S):
Pathfinder All
Frontier and Xterra up to April 10, 2000
Quest up to May 10, 2000

APPLIED ENGINE #:
Pathfinder All
Frontier, Xterra and Quest Before VG33-424030M

SERVICE INFORMATION; Piston Replacement on VG33E Engines

Moly-Coated Piston Skirt Applied To # 3, # 4, # 5





Engines built before VG33-424030M (installed in the WD22, D22 and V41 series) and all VG33E engines installed in the R50 series used a non-coated piston in cylinders # 1, # 2, # 5 & # 6. If it is necessary to replace a piston(s) in one of these Applied Vehicles, install non-coated pistons of the appropriate grade into cylinders # 1, # 2, and # 6. Install moly-coated pistons of the appropriate grade into cylinders # 3, # 4, and # 5. Refer to Figure 1 for cylinder locations.

NOTE:
Coated pistons are designed to use a tighter piston-to-bore clearances than non-coated pistons to reduce noise and prevent scuffing.

Piston-To-Bore Clearance Specification





Always carefully measure the cylinder bores for wear, out-of-round, and taper as described in the EM section of the appropriate Service Manual. When replacing pistons, always observe the clearance specifications shown on the table:

If any bore exceeds the limit, rebore all cylinders and fit oversize pistons.

All Oversize Pistons Are Coated

All service parts for .25 and .5Omm oversize pistons are moly-coated. If the cylinder block will be machined to accept oversize pistons, order 6 pistons and measure each one. Finish hone the cylinders to obtain the correct clearance as specified in the above table for each piston/cylinder combination.





PARTS INFORMATION; Table of Piston P/Ns

NOTE:
Grade stamps may no longer be appropriate for engines that have been in service. Always select pistons based on careful piston-to-bore clearance measurements.