K 1500 Suburban 4WD V8-393 6.5L DSL Turbo (1994)
Piston: Technical Service Bulletins
Engine - Production Piston Grade Size Stamp
Group Ref.: 6 - Engine
Bulletin No.: 376120
Date: July, 1994
INFORMATION
SUBJECT:
PRODUCTION PISTON GRADE SIZE STAMP
MODELS:
1994 CHEVROLET AND GMC TRUCK C/K, P MODELS AND G VAN WITH 6.5L DIESEL ENGINE (VINs F, P, S, Y - RPOs L65, L49, L56, L57)
PISTON GRADE SIZE STAMP INFORMATION:
Beginning with the 1994 model year, a production piston grade size stamp will be located in one place only on the cylinder block oil pan rail. Previously,
the pan rail was stamped in eight places (one for each engine cylinder) because more than one production piston grade size could be used in the same
cylinder block (i.e., the pistons were selected based on the size of each finished cylinder).
Due to manufacturing improvements, the need to have more than one production standard piston grade size has been eliminated, thus it is no longer
necessary to stamp the pan rail in more than one place on the cylinder block pan rail.
A 0.13 mm oversize production piston is available for in-plant rework of cylinders not meeting the production standard specification. These production
oversize cylinder bores are identified by an "S" metal stamped on the pan rail next to any reworked cylinder. A "J" will also be metal stamped in a single
place on the pan rail to represent that all remaining cylinders are production standard.
In production, pistons are identified by the letters "J," "S", "JT," or "ST" paint stamped on their face and wrist pin boss surfaces. "J" pistons are
production standard and "S" pistons are production oversize for naturally aspirated 6.5L diesel engines (L49, L57). "JT" pistons are production standard
and "ST" pistons are production oversize for turbocharged 6.5L diesel engines (L56, L65). Turbocharged engines require pistons having an anodized top
of dome to withstand their inherent additional mechanical and thermal loads.
SERVICE INFORMATION:
All service pistons for 1994 6.5L diesel engines (VINs F, P, S, Y) will be "T" pistons. Refer to the following chart for piston and cylinder bore
specifications:
SERVICE PARTS INFORMATION:
