SMU - SECTION 6A2 - ENGINE MECHANICAL - REVISED CAMSHAFT. Cadillac DeVille 1994

SUBJECT: SERVICE MANUAL UPDATE - SECTION 6A2 - ENGINE MECHANICAL - REVISED CAMSHAFT TIMING PROCEDURE

MODELS: 1993 CADILLAC ALLANTE 1993 CADILLAC ELDORADO ETC AND SPORT COUPE, SEVILLE STS 1994 CADILLAC ELDORADO ETC AND SPORT COUPE, SEVILLE STS AND SLS 1994 CADILLAC CONCOURS WITH 4.6L ENGINE (RPOS LD8 AND L37 - VIN CODES Y AND 9)

WHEN SERVICING A 1993-94 NORTHSTAR V-8 ENGINE CYLINDER HEAD, AND CAMSHAFT REMOVAL IS REQUIRED, PLEASE REFER TO THE FOLLOWING INFORMATION TO ENSURE PROPER CAMSHAFT TIMING DURING REASSEMBLY. THE SERVICE MANUAL CONTAINS INCORRECT INFORMATION CONCERNING THE INSTALLATION SEQUENCE OF THE SECONDARY CAMSHAFT DRIVE CHAINS.

PROCEDURE:

IF THE SECONDARY DRIVE CHAINS HAVE BEEN REMOVED, YOU MUST INSTALL THE **LEFT** CYLINDER HEAD SECONDARY DRIVE CHAIN **FIRST** AND THE **RIGHT** CYLINDER HEAD SECONDARY DRIVE CHAIN **SECOND**. SERVICE MANUAL PROCEDURES 10 AND 11 SHOULD REFERENCE THE **LEFT** INTAKE AND EXHAUST CAMSHAFTS INSTEAD OF THE RIGHT, WHILE STEP 15 SHOULD REFERENCE THE **RIGHT SIDE** CAMSHAFTS INSTEAD OF THE LEFT.

WHEN CAMSHAFT REMOVAL IS REQUIRED, PLEASE NOTE THE FOLLOWING:

- REFERENCES TO THE RIGHT AND LEFT CYLINDER HEADS ARE FROM THE **REAR** OF THE ENGINE.

- THE 4.6L NORTHSTAR IS AN **INTERFERENCE** ENGINE, MEANING THAT IT IS NOT FREE SPINNING AND THE PISTONS WILL STRIKE THE VALVES IF THE CRANKSHAFT IS ROTATED WITH THE CAMSHAFT DRIVE DISCONNECTED OR THE CAMSHAFTS ARE OUT OF TIME.

- THE CAMSHAFT TENSIONER LEVERS ARE NOT INTERCHANGEABLE AND ARE MARKED WITH **LEFT** AND **RIGHT** DESIGNATIONS.

- THE SECONDARY CHAINS, CHAIN GUIDES AND CHAIN TENSIONERS **ARE** INTERCHANGEABLE.

- THE **LEFT** CYLINDER HEAD SECONDARY DRIVE CHAIN **MUST** BE INSTALLED ON THE INTERMEDIATE SPROCKET **FIRST**.

REFERENCE THE SECTION "SETTING CAMSHAFT TIMING" IN THE APPROPRIATE SERVICE MANUAL FOR COMPLETE CAMSHAFT TIMING PROCEDURE.

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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.