New Product Information for Chevrolet Astro - 4WD 1999
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:
| • | A component comparison from the previous year |
| • | 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 |
Component Comparison
| • | New engine block M10 X 1.5 metric attachments for
the engine mounts, the starter motor, and the transmission |
| • | New oil pan M10 X 1.5 metric attachment for the
transmission |
| • | New crankshaft with a unique crankshaft clutch pilot bearing hole
and 3 mm shortened engine flywheel mounting flange |
| • | Revised crankshaft rear oil seal and crankshaft rear oil seal
housing for the shortened crankshaft engine flywheel mounting flange |
| • | New engine flywheels for shortened crankshaft engine flywheel
mounting flange |
| • | Eliminated the fuel pump switch from the engine oil pressure gauge
sensor |
| • | Revised the water pump seal |
| • | Revised the engine coolant thermostat |
Engine Block and Oil Pan Partial Metrification
| • | The engine block has been
changed to M10 X 1.5 metric fasteners for the starter motor
(1), the transmission (3), and the engine mount attachments (4). |
| • | The oil pan has been changed to M10 X 1.5 metric
fasteners for the transmission attachments (2). |
Partial Metric Engine Block Identification
| • | Engine blocks manufactured
at the Saginaw casting plant are cast with 090M (1) and 14099090M (4) casting
numbers for partial metric engine block identification. |
| • | Engine blocks manufactured at the Defiance casting plant are cast
with 090M (3) and 14099090M (2) casting numbers for partial metric engine
block identification. |
Torque Values and/or Fastener Tightening Strategies
| • | Cylinder head bolts, the crankshaft bearing cap bolts, and the
connecting rod bolts apply a torque angle strategy. |
| | In an on-vehicle situation where a torque angle meter may not fit into
the vehicle packaging, a three step tightening process may be followed using
a torque wrench. |
| • | 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
Engine mechanical specifications remain the same as the 1998 products.
New Sealants and/or Adhesives
Additional applications have been added to the table including:
| • | Balance shaft driven gear bolt |
| • | Expansion cup plug (camshaft rear bearing hole) |
| • | Expansion cup plug (balance shaft rear bearing hole) |
| | Refer to sealers, adhesives, and lubricants. |
Disassembly and Assembly Procedure Revisions or Additions
| • | A revised design Teflon® rear crankshaft oil seal |
| • | Engine block plug information has been enhanced to include the
dowel pins (cylinder head locator) and dowel straight pins (transmission locator). |
| • | Crankshaft Rear Oil Seal and Housing has been enhanced to include
the spring type S pin (crankshaft rear oil seal housing locator). |
| • | Intake Manifold Assemble information includes enhanced fuel seal
installation detail. |
| • | Discard all used gaskets, seals, or O-ring seals unless otherwise
indicated. |
| | Gaskets, seals, or O-ring seals that can be reused will be identified
in the specific service procedure. |
Engine Mechanical Diagnostic Procedure Revisions
| • | Valve Train diagnostic information is now provided in table form. |
| | Potential or probable causes are supplied for each specific concern. |
| • | Engine Noise diagnostic information is now provided in table form. |
| | Potential or probable causes are supplied for each specific concern. |
New Special Tools Required
| • | Tool J 35621-B
is a revision of the J 35621-A, and can be used to service All the
crankshaft rear oil seal installation applications. |
| • | Tool J 41712
has been added for removal and installation of the engine oil
pressure gauge sensor. |
