GROUP 6A ITEMS-QUICK SERV INFO MULTIPLE SUBJECTS

QSI (QUICK SERVICE INFORMATION) ITEMS - GROUP 6A

THIS BULLETIN CONTAINS MULTIPLE SUBJECTS. PAGE THROUGH TO DESIRED SUBJECT.

GR. 6A DIESEL TRANSFER PUMP COVER

WE HAVE RECEIVED REPORTS CONCERNING DAMAGE TO THE TRANSFER PUMP COVER ON THE DIESEL INJECTION PUMP. WHEN REMOVING THE INJECTION LINES, IT IS IMPORTANT THAT YOU DO NOT DAMAGE THE TRANSFER PUMP COVER (BLACK IN COLOR) WITH THE WRENCH. IF THE COVER IS DAMAGED (A DIMPLE OR CRACK), IT COULD ALLOW AIR TO ENTER THE FUEL SYSTEM CAUSING A ROUGH ENGINE IDLE. CARE SHOULD BE TAKEN WHEN SERVICING THIS PUMP.

GR. 6A DIESEL GOVERNOR WEIGHT RETAINER PIN WEAR

WHILE MAKING A GOVERNOR WEIGHT RETAINER RING REPAIR, THE RETAINER PIN SHOULD BE INSPECTED FOR DAMAGE. IF THE PIN IS BENT, LOOSE OR EXCESSIVELY WORN, CHANGE THE RETAINER. THE POINT AT WHICH THE PIN IS EXCESSIVELY WORN IS WHEN THE PIN IS WORN IN EXCESS OF HALF THE SMALLER DIAMETER, AS SHOWN IN THE FIGURE BELOW. REMEMBER TO REMOVE ANY SHARP EDGES THAT MAY CUT THE RETAINER RING.

GR. 6A DIESEL - BASIC SERVICE ENGINE

THE 1980-81 DIESEL BASIC SERVICE ENGINE AVAILABLE FROM GENERAL MOTORS WAREHOUSING AND DISTRIBUTION DIVISION (GMWDD) WILL NO LONGER CONTAIN DOWEL PINS ON THE CYLINDER BLOCK SURFACE TO LOCATE CYLINDER HEADS AND GASKETS. THIS IS BEING DONE TO REDUCE BASIC ENGINE PART NUMBERS STOCKED BY GMWDD. WHEN ORDERING A BASIC ENGINE, DEALERS WILL NEED TO ORDER QUANTITY ONE OF PART NUMBER 585927 (DOWEL PIN); THIS IS A BOX OF 20 PIECES WHICH IS ENOUGH TO DO FIVE ENGINES. THEY SHOULD BE IN- STALLED IN THE NEW BLOCK IN THE SAME LOCATION AS IN THE ENGINE BEING REPLACED. HOLES WILL BE PROVIDED IN THE SERVICE BLOCKS AT THE NECESSARY DOWEL PIN LOCATION POINTS. A NOTE WILL BE FORTHCOMING IN THE GMWDD PARTS BOOKS TO THIS EFFECT.

REFER TO QSI NOTE IN SERVICEMAN BULLETIN NO. 81-36 CONCERNING 1980 AND 1981 SERVICE ENGINE ASSEMBLIES.

GR. 6A DIESEL - ALL 1981 SERIES - BLACK SMOKE AND LOW POWER

WHEN INVESTIGATING A CONDITION OF BLACK SMOKE AND LOW POWER, CHECK FOR THE PROPER OPERATION OF THE EXHAUST PRESSURE REGULATOR (EPR) VALVE. THE VALVE IS CLOSED AT IDLE TO INCREASE EXHAUST PRESSURE WHICH INCREASES EGR FLOW TO THE ENGINE. THE EPR VALVE OPENS ABOVE IDLE TO ACHIEVE A NORMAL EGR LEVEL FOR TYPICAL DRIVING.

GR. 6A DIESEL - WHITE SMOKE COLD ENGINE START

WHITE SMOKE AT START-UP AFTER SITTING OVERNIGHT IS THE RESULT OF OPENING THE EXHAUST VALVES BEFORE THE FUEL HAS COMPLETELY BURNED. THE HPCA (HOUSING PRESSURE COLD ADVANCE) FEATURE OF THE INJECTION PUMP IS DESIGNED TO ADVANCE THE TIMING BY 3 DEG. DURING WARM-UP TO PREVENT THIS CONDITION. THE HPCA SOLENOID LOCATED INSIDE THE FUEL INJECTION PUMP COVER IS ACTIVATED BY CURRENT FLOW THROUGH THE COOLANT SWITCH WHEN ENGINE TEMPERATURE IS LESS THAN 120 DEG. F (COLD ENGINE). CHECK FOR CURRENT AT THE HPCA TERMINAL LOCATED ON THE SIDE OF THE INJECTION PUMP COVER AT COOLANT TEMPERATURES BELOW 120 DEG. F (COLD ENGINE). IF NO CURRENT AT THE HPCA, REPAIR AS NECESSARY. IF CURRENT IS AVAILABLE AT HPCA TERMINAL, REMOVE THE INJECTION PUMP COVER AND RECONNECT THE SOLENOID FEED WIRE AND GROUND PUMP COVER, THE SOLENOID INSIDE COVER SHOULD ACTIVATE. IF THE SOLENOID DOES NOT ACTIVATE, THE COVER ASSEMBLY SHOULD BE SENT TO A ROOSA-MASTER REPAIR STATION FOR CORRECTION.

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.