The purpose of New Product Information is to highlight or indicate important
product changes from the previous model year.
Changes may include one or more of the following items:
| • | Torque values and/or fastener tightening strategies |
| • | Changed engine specifications |
| • | New sealants and/or adhesives |
| • | Disassembly and assembly procedure revisions |
| • | Engine mechanical diagnostic procedure revisions |
| • | New special tools required |
| • | A component comparison from the previous year |
Torque Values and/or Fastener Tightening Strategies
| • | All fasteners and threaded holes on the LS1 engine utilize metric
threads. |
| • | Cylinder head, connecting rod, crankshaft balancer, and main bearing
cap bolts now apply a torque angle strategy. |
| • | Certain fasteners should not be reused. Bolts, studs, or other
fasteners that must be replaced will be called out in the specific service
procedure. |
Changed Engine Specifications
| • | Cylinder honing is permitted on the 1998 LS1 cylinder block. |
| | A 0.25 mm (0.010 in) oversize piston and piston ring set
are available for service. |
New Sealants and/or Adhesives
| • | Threadlocking material is used on the fuel rail, intake manifold,
cylinder head M8, and exhaust manifold bolt threads. |
| • | A pipe sealant type material is used on the engine block coolant
and oil gallery plugs, oil pressure sensor threads, and engine block oil pan
surface. |
Disassembly and Assembly Procedure Revisions
| • | Dowel pins align and position the LT1 front cover and rear crankshaft
oil seal housing to the engine block. |
| | The LS1 front and rear engine
covers are adjustable and must be aligned properly with the oil pan surface
and crankshaft assembly. |
| • | The LS1 oil pan is a structural member of the powertrain and must
be aligned properly with the rear of the engine block and transmission bellhousing. |
| • | Crankshaft balancer installation has a specific procedure to ensure
complete installation. |
| • | The piston, pin, and connecting rod are to be serviced as an assembly. |
| • | Newer design pistons have a graphite coated piston skirt. The
coated skirt outside diameter (OD) may be slightly larger than the
cylinder bore inside diameter (ID) and the piston assembly may have
a slight interference fit to the cylinder bore during initial installation. |
Engine Mechanical Diagnostic Procedure Revisions
Base Engine Misfire, Valve Train, and other diagnostic information is
now provided in table form. Potential or probable causes are supplied for
each specific concern.
New Special Tools Required
| • | A variety of new tools have been developed to assist in engine
disassembly, assembly, and on-vehicle service. |
A Component Comparison from the Previous Year
| • | The 1997 5.7 liter LT1 engine has been replaced by the new 5.7
liter LS1 engine. |
| • | Some of the new features include the following: |
| • | LT1 has a iron cylinder block. LS1 has an aluminum cylinder block
with cast in place steel liners. |
| • | LT1 has a cast aluminum one piece intake manifold. LS1 has a composite
one piece design |
| • | LT1 crankshaft has two bolt main caps with the thrust bearing
in the number five journal. The LS1 crankshaft has six bolt main caps with
the thrust bearing in the number three journal. |
| • | LT1 ignition system includes one ignition coil, crankshaft sensor,
and a distributor assembly. LS1 ignition system includes a crankshaft sensor,
camshaft sensor, and eight individual ignition coils. |
| • | LT1 has a stamped steel oil pan. LS1 has a cast aluminum structural
oil pan. |
