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Commodore (VN-VZ) / HSV

1988-2006 / Sedan / Estate / Australia

All Commodore (VN-VZ) / HSV problems All workshop issues
Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Supercharger Bypass Valve Failure (L67 supercharged V6)

Symptoms

Loss of boost, rattling from the supercharger, reduced performance. The supercharger may make a whining noise that changes with the valve's operation.

Cause

The bypass valve controls how much air recirculates through the supercharger at part throttle. The valve's internal diaphragm deteriorates, causing it to stick open (no boost) or closed (excessive boost at part throttle, which loads the engine unnecessarily).

Fix

Replace the bypass valve actuator.

Parts: $80-150 aftermarket.

This is a 30-minute job.

Some owners upgrade to a manual bypass valve for tuned applications.

Cost mentioned in fix
$80-150

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Other known issues

Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Intake Manifold Gasket Leak

Coolant leak at the junction of the intake manifold and cylinder heads. May present as coolant loss without a visible external leak (coolant enters the intake ports), or as a coolant stain on the side of the engine. Engine may run rough or misfire if coolant enters the combustion chamber.
Critical Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Harmonic Balancer Failure (Ecotec, VS onwards)

A wobbling pulley on the front of the crankshaft. Knocking or rattling noise from the front of the engine. The drive belt may track poorly or come off.
Critical Engine, V6 (Alloytec 3.6L, VZ)

Timing Chain and Guide Failure

Rattling noise on cold start that may persist after warm-up. Check engine light with codes related to camshaft timing. Rough idle, misfiring, loss of power. In severe cases, the engine won't start or runs extremely poorly.
Critical Engine, V6 (Alloytec 3.6L, VZ)

Oil Leaks from Timing Cover

Oil weeping or dripping from the front of the engine, behind the harmonic balancer area.
Common Engine, V8 (Holden 304, VN-VS)

Hydraulic Lifter Noise

Ticking or tapping noise from the top of the engine, worst on cold start. May persist for several minutes or be constant.
Critical Engine, V8 (Holden 304, VN-VS)

Oil Pump Drive Shaft Failure

Sudden loss of oil pressure. Oil pressure warning light illuminates. Engine noise increases rapidly. Catastrophic engine failure if not caught immediately.
View all 20 Commodore (VN-VZ) / HSV problems