| Subject: | Severe Engine Damage in One Cylinder |
| Models: | 2006-2007 Buick Terraza |
| 2006-2007 Chevrolet Impala, Monte Carlo, Malibu, Uplander |
| 2006-2007 Pontiac G6, Montana SV6 |
| equipped with 3.9L LZ9, LGD engine (VIN Code 1 or W) |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some owners may comment that the engine will not start. Depending on the severity of the failure the engine may or may not crank.
The bushing located inside the upper intake manifold that supports the end of the intake manifold tuning valve shaft may be missing. If the bushing is missing it may result in the tip on the end of the tuning valve shaft breaking off. If the tip of the
shaft were to break off it could work its way down through the intake manifold and cylinder head and into the combustion chamber of one cylinder. As the piston in that cylinder moves up to top dead center contact with the broken tip may take place resulting
in severe engine damage.
Recommendation/Instructions:
If severe engine damage is found in one cylinder then remove the intake manifold tuning valve from the upper intake manifold. Inspect the intake manifold tuning valve to see if the tip (1) of the shaft is present.
| • | If the tip of the valve is missing, then install a new upper intake manifold and intake manifold tuning valve when repairing the engine.
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| • | If the tip of the valve is NOT missing, then proceed with your diagnosis on what caused the severe engine damage.
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Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
