For 1990-2009 cars

# OIL OUT THE TRANSMISSION VENT- PROBABLE CAUSES

WHEN DIAGNOSING AN "OIL OUT THE VENT" CONDITION, IT IS IMPORTANT TO CHECK ALL THE POSSIBLE CAUSES. PROBABLE CAUSES INCLUDE EXCESSIVE FLUID IN THE TRANSMISSION (OVERFILL), RESIDUAL OIL ON TOP OF THE TRANSMISSION FROM SPILLAGE DURING FILLING, OR A LEAK AT THE PRESSURE TAP PLUG. ONLY AFTER ALL POSSIBILITIES HAVE BEEN ELIMINATED, PROCEED AS FOLLOWS: 1.REMOVE THE TRANSMISSION FROM THE CAR. 2.DISASSEMBLE THE TRANSMISSION TO THE CASE COVER. 3.REMOVE THE CASE COVER AND INSPECT THE AREAS ADJACENT TO THE MANUAL VALVE FOR FLATNESS TO CASE AND EXTERNAL POROSITY. 4.WASH CASE COVER COMPLETELY WITH SOLVENT TO REMOVE ALL TRANSMISSION OIL AND DRY BEFORE PROCEEDING WITH THE FOLLOWING DRILLING OPERATION. 5.DRILL A 6.0MM (1/4 INCH) HOLE THROUGH THE BREATHER AREA OF THE COVER AS INDICATED IN ILLUSTRATION. LATE 1980 PRODUCTION HAS THIS PASSAGE AND DOES NOT REQUIRE DRILLING. USE A SMALL DRILL OR PUNCH TO START HOLE. WHEN DRILLING OPERATION IS COMPLETED, DEBURR BOTH SIDES OF HOLE AND BRUSH OUT CHIPS. RINSE COVER COMPLETELY WITH SOLVENT. 6.REPLACE BOTH SPACER PLATE GASKETS WITH NEW SPACER PLATE GASKETS, PART #8637096. 7.REASSEMBLE TRANSMISSION.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.