The crankshaft position sensor, ignition module, and/or powertrain control module (PCM) may fail resulting in illumination of the Check Engine Light with ignition system related fault codes stored in the PCM. Patience is necessary when dealing with this specific situation as normal diagnostic procedures are not effective. In many cases, the best option is to replace parts, one at a time until the fault is corrected.
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The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Our technicians tell us that operating the engine with a coolant/oil mix can result in internal engine damage. Replacing the intake manifold gasket should correct these leaks.
An engine oil leak may develop from the rear of the engine. This is commonly caused by a failed oil pump drive o-ring seal. The leaking o-ring should be replaced to correct this concern.
The serpentine belt tensioner pulley may wear out. Our technicians tell us that in order to get a new pulley from General Motors you must purchase a complete belt tensioner assembly.
The engine vacuum hose to the MAP sensor may crack resulting in a vacuum leak causing the engine to run rough and/or stall.
An engine oil leak may develop from the oil pump drive O-ring. This can often be confused with an intake manifold gasket leak. Careful inspection is required to determine the exact cause of the leak. Replacement of the failed 0-ring will commonly correct this concern.
The upper intake manifold gasket and/or a PCV vacuum lines/hoses can develop vacuum leaks with age. This type of leak can result in a higher that normal or rough idle.