INFO. USE OF'SURFACE CONDITIONING DISCS'

SUBJECT: INFORMATION - USE OF "SURFACE CONDITIONING DISCS"

MODELS: 1998 AND PRIOR PASSENGER CARS AND TRUCKS

THE USE OF "SURFACE CONDITIONING DISCS" -

WHEN CLEANING ENGINE GASKET SEALING SURFACES, AND/OR CLEANING PARTS FROM AN ENGINE WHICH ARE TO BE REUSED; SURFACE CONDITIONING DISCS (TYPICALLY A WOVEN FIBER PAD DESIGN) WHICH CONTAIN ABRASIVES, SUCH AS A HIGH AMOUNT OF ALUMINUM OXIDE, ARE NOT RECOMMENDED.

THE USE OF SUCH SURFACE CONDITIONING DISCS DISLODGE ALUMINUM OXIDE (FROM THE DISC) AND METAL PARTICLES, WHICH CAN LEAD TO PREMATURE ENGINE BEARING FAILURE.

THE PRESENCE OF ALUMINUM OXIDE IN ENGINE OIL HAS BEEN SHOWN TO CAUSE PREMATURE ENGINE BEARING FAILURE. IN SOME CASES THIS FAILURE OCCURS IN AS LITTLE AS 1,000 MILES (2,200 KM) OR LESS AFTER THE REPAIR HAS BEEN MADE.

SURFACE CONDITIONING DISCS MAY GRIND THE COMPONENT PART MATERIAL AND IMBED IT INTO THE DISC. THIS CAN RESULT WHEN MORE AGGRESSIVE GRINDING OF THE GASKET SURFACE TAKES PLACE. PROCEDURE: A NEW PRODUCT FROM 3M(R) AUTOMOTIVE AFTERMARKET DIVISION, THE ROLOC BRISTLE DISC*, IS NOW AVAILABLE WHICH ADDRESSES SOME OF THE ABOVE CONCERNS.

* WE BELIEVE THIS PRODUCT TO BE RELIABLE. THERE MAY BE ADDITIONAL MANUFACTURERS OF SUCH PRODUCTS. GENERAL MOTORS DOES NOT ENDORSE, INDICATE ANY PREFERENCE FOR OR ASSUME ANY RESPONSIBILITY FOR ANY ITEMS WHICH MAY BE AVAILABLE FROM THIS FIRM, OR FOR ANY SUCH ITEMS WHICH MAY BE AVAILABLE FROM OTHER SOURCES.

CAUTION:

TO AVOID PERSONAL INJURY FOLLOW STANDARD SAFETY PRECAUTIONS, INCLUDING THE USE OF SAFETY GLASSES, SHOULD BE OBSERVED DURING SURFACE PREPARATION.

READ THE SAFETY INSTRUCTIONS INCLUDED WITH THE PRODUCT BEFORE USE.

REMOVE BY HAND, WITH A SCRAPPER (PLASTIC SCRAPPER ON ALUMINUM SURFACES), THE BULK OF MATERIAL ON THE COMPONENT SURFACE BEFORE USING THE 3M(R) ROLOC BRISTLE DISC.

NOTICE: DUE CARE MUST BE TAKEN TO AVOID THE ENTRY OF ANY MATERIAL INTO THE ENGINE BLOCK OIL AND COOLANT PASSAGES WHEN CLEANING COMPONENT SURFACES.

THE PRESENCE OF FOREIGN MATERIAL IN ENGINE OIL HAS BEEN SHOWN TO CAUSE PREMATURE ENGINE BEARING FAILURE.

COVER OR BLOCK ALL ENGINE PORTS (ENGINE OIL AND COOLANT) AND OPEN AREAS (CYLINDER BORES, LIFTER VALLEY, ETC.) TO PREVENT POSSIBLE CONTAMINATION WHEN WORKING ON THE ENGINE.

VACUUM UP ALL CONTAMINANTS (I.E. DIRT, GASKET MATERIAL, ETC.).

IMPORTANT: ENGINE COMPONENTS, CLEANED WITH 3M ROLOC BRISTLE DISC, SHOULD BE THOROUGHLY CLEANED BEFORE RE-INSTALLING THEM ON THE ENGINE BLOCK.

THE USE OF A VACUUM, SPRAY CLEANER GM P/N 12346139 OR 12377981, PARTS CLEANER, ETC. TO REMOVE ALL TRACES OF CONTAMINANT IS SUGGESTED.

THE DISCS (SEE FIGURE 1--3M(R) ROLOC DISC IDENTIFICATION) ARE AVAILABLE IN DIFFERENT GRIT LEVELS, WITH SUGGESTED APPLICATIONS AS FOLLOWS:

3M(R) PART COLOR/ SUGGESTED NUMBER** DESCRIPTION*** APPLICATION QUAN. --------- ------------- ------------ ----- WHITE 120X GRIT ALUMINUM BOX OF ROLOC BRISTLE DISC (MILD 10 07532 1" DIAMETER ABRASIVE) 07528 2" DIAMETER 07529 3" DIAMETER

YELLOW 80X GRIT ALUMINUM OR BOX OF ROLOC BRISTLE DISC CAST IRON/ 10 07531 1" DIAMETER STEEL 07525 2" DIAMETER (MEDIUM 07527 3" DIAMETER ABRASIVE)

GREEN 50X GRIT CAST IRON/ BOX OF ROLOC BRISTLE DISC STEEL (HARSH 10 07530 1" DIAMETER ABRASIVE) 07524 2" DIAMETER 07526 3" DIAMETER

*** THE ABOVE 3M(R) ROLOC BRISTLE DISCS ARE TO BE USED WITH THE CORRECT DISC PAD ASSEMBLIES LISTED BELOW.

CAUTION:

NON-3M(R) BACK-UP PAD'S MAY HAVE A DEEPER THREADED CAVITY WHICH CAUSES THE BUTTON (ON THE DISC) TO CONTINUE TO TIGHTEN DOWN DURING USE. THIS CAN CAUSE THE BUTTON TO SEPARATE FROM THE DISC RESULTING IN DISC FLY OFF AND POTENTIAL OPERATOR HARM.

3M(R) PART NUMBER** DESCRIPTION QUAN. --------- ------------------------- ------ 05538 1" ROLOC DISC PAD ASSEMBLY BOX OF 05539 2" ROLOC DISC PAD ASSEMBLY ONE (1) 05540 3" ROLOC DISC PAD ASSEMBLY

NOTICE: WHEN USING ANY ABRASIVE MATERIAL, PARTICULARLY ON ALUMINUM SURFACES, CARE MUST BE TAKEN TO AVOID DAMAGE TO THE SURFACE AREA. EXCESSIVE MATERIAL REMOVAL MAY RESULT IN DAMAGE TO SEALING SURFACES.

** THESE COMPONENTS CAN BE OBTAINED FROM LOCAL 3M(R) SUPPLIERS. THE BRAND NAMES "3M" AND "ROLOC" ARE TRADEMARKS OF MINNESOTA MINING AND MANUFACTURING COMPANY, ST. PAUL, MINNESOTA 55144.

PARTS INFORMATION:

PART NUMBERS DESCRIPTION ------------ ----------- 12346139, 12377981 SPRAY CLEANER

PARTS (SPRAY CLEANERS ONLY) ARE CURRENTLY AVAILABLE FROM GMSPO.

FIGURES: 01 ATTACHMENTS: 00

FIGURE 1 - 3M(R) ROLOC BRISTLE DISC IDENTIFICATION 1 - SHAFT (TYPICAL) 2 - BACK-UP PAD 3 - ROLOC BRISTLE DISC

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.

COPYRIGHT 1998. GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.