Grand Prix V6-204 3.4L DOHC (1992)
Camshaft: Customer Interest
Cold Engine - Lifter Ticking Noise
File In Section: 6 - Engine
Bulletin No.: 57-61-09
Date: November, 1995
Subject:
Cold Engine Lifter Tick Noise (Modify Camshaft Thrust Plate Oiling)
Models:
1991-94 Chevrolet Lumina
1995 Chevrolet Lumina, Monte Carlo - Built Prior to VIN Breakpoint S9148603 1991-94 Oldsmobile Cutlass Supreme
1991-94 Pontiac Grand Prix
with 3.4L DOHC V6 Engine (VIN X - RPO LQ1)
Condition
Some owners may comment on a tick type noise on a cold engine. This noise will be present after a minimum of a 2 hour cold soak. The engine may be
quiet on the initial start for approximately 30-60 seconds, then the tick will appear for 5-10 minutes and then goes away after the engine is warmed up.
This tick noise will not be heard on a hot restart. This noise is not detrimental to the dependability or reliability of the engine.
Cause
Lifter tick noise is a function of oil temperature. Under cold conditions, high oil pressure fluctuations in the lifter gallery are unseating the internal lifter
check ball which allows the lifter to momentarily collapse. Lifter gallery pressure fluctuations at low speed vary significantly with oil temperature. Thus,
tick noise is dependent on the timing of a rapid oil pressure drop in the lifter gallery.
Correction
An Oiling Scheme Improvement Package has been developed. For engines produced after August 23, 1994 the improved system will have a camshaft
which will not have the thrust plate groove 4 mm oiling hole. The cup plug in the camshaft will have a 2 mm hole to oil the thrust plate. By restricting the
flow of oil from the lifter gallery with a 2 mm hole, it improves overhead oil pressure and dampens the oil pulsations of cold engine oil. The Oiling
Scheme Improvement Package is available as a service repair kit, part number 12538687. The repairs involve eliminating the 4 mm thrust plate groove
