Riviera V6-3.8L SC VIN 1 (1995)
Valve Guide Seal: Customer Interest
Engine - Continuous Spark Knock/Oil Consumption
SECTION: 6 - Engine
NO.: 57-61-13
DATE: May, 1995
SUBJECT:
Continuous Spark Knock or Excessive Oil Consumption (Replace Valve Stem Seals)
Models:
1993 Buick Riviera
1993-95 Buick LeSabre, Park Avenue, Regal
1995 Buick Riviera
1993-95 Chevrolet Lumina APV
1993-95 Oldsmobile Eighty Eight, Ninety Eight, Silhouette
1993-95 Pontiac Bonneville, Trans Sport
with 3800 Engine (VINs 1, L - RPOs L67, L27)
Vehicles built before November 1, 1994.
CONDITION
Some owners may comment about a continuous spark knock during normal driving conditions and/or excessive oil consumption.
CAUSE
Figure 1
The condition may be caused by one or more valve stem seals with a broken retaining band. A broken valve stem seal retaining band distorts the seal
allowing oil to be drawn down the valve guide and into the combustion chamber. REFER TO ILLUSTRATION. When oil is burned inside the
combustion chamber, the effective octane rating is lowered considerably and therefore leads to spark knock. Furthermore, the resulting carbon deposit
build up inside the combustion chamber will raise the effective compression ratio, aggravating the spark knock condition.
SERVICE INFORMATION
To diagnose the condition, the technician should drive the vehicle with a Scan Tool installed. Check for and repair any diagnostic codes that may be set.
If scanner readings appear to be normal, then program the Scan Tool to observe Electronic Spark Control (ESC) activity. Lightly accelerate the vehicle
