0 1997 Buick Century Limited 3.1/ 3.4L COLD ENGINE TICK OR RATTLE AFTER START-UP (REPLACE PISTON/ PIN ASSEMBLY)

Some customers may comment on a ticking type noise that begins shortly after cold engine start-up and gradually diminishes as the engine warms up. In most cases, the noise is gone after five (5) minutes. In severe cases, the noise may not disappear when lhe engine is hot. CAUSE Under normal design tolerances when the piston pin bore is produced at the maximum tolerance and the piston pin is produced at the minimum tolerance (min-max tolerance) trace noise levels can occur.

This level of noise does not affect the reliability or durability of the product. CORRECTION If piston-to-pin noise is detected and the customer desires the condition to be corrected, replace all six pistons with pin assemblies. The new piston sets have a minimal piston-to-pin clearance. Remember, piston-to-pin noise occurs in both park and drive at engine idle rpm and it varies in intensity depending on the number of pistons involved. A ticking sound means one piston is affected whereas a rattle or diesel type sound indicates more than one piston affected.

The following should also be checked: 1. On W-Cars, make sure the right side engine splash shield is not contacting the engine crankshaft balancer. This condition usually happens cold and is caused by the shield curling when cold. 2. Reference Service Bulletin 57-71-06 for transmission rattle noise often confused for engine rattle noise. 3. Reference Service Bulletin 47-61-36 for Accessory Drive Belt Tensioner noise. 4. Check cylinder bore diameter and piston diameter as outlined in the Service Manual. Use the procedure in the appropriate Service Manual for piston replacement. Service Bulletin 57-61-24 (Section 6 – Engine). NOTE: Excessive cylinder bore to piston diameter clearance can cause a similar type noise. NOTE: When installing the new piston and pin assembly onto the existing rods, use extreme care to avoid damage to either the pin or piston bore. If damage to these areas occurs, the noise will return because the damage will cause wear and excessive clearance

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