Engine Mechanical problem
1999 Oldsmobile Alero 6 cyl Front Wheel Drive Automatic

I have a 1999 olds alero, 3.4 liter, 6 cylinder. I am not getting any oil pressure. So far I replaced the oil pump in the oil pan. The hex drive shaft which drives the oil pump does not look worn. I turned over the engine to see if the oil pump 'drive' shaft turns. It does not turn. The oil pump 'drive' shaft is firmly engaged with the 'upper' drive gear. I even tried to turn the oil pump 'drive' shaft with a socket & ratchet to see if the drive gear was stripped. It didn't turn. WHAT COULD BE THE PROBLEM?
John

Hello John
I have attached a pic showing the drive gear to the camshaft. Is it possible with the oil pump out and extension removed to look up to see as someone turns the crankshaft by hand to see if the drive gear is moving with the camshaft?
If I understand, you were not getting oil pressure but the engine was still running and you shut it off when you saw there was not pressure I assume.
If this did not happen and the engine stopped running, my thought there is the timing chain is broken if the top of the engine is not turning and the bottom is. Thus the cam is not turning even though the engine is spinning.
Here is the probable cause for no oil pressure. If you notice the 2nd to the last item is a worn or poorly machined camshaft. You are to replace the camshaft which I would think the gear is attached to it.
Let us know if this helps.

Low or No Oil Pressure
The following conditions may cause low or no oil pressure:
• Low oil level Fill to the full mark on the oil level indicator.
• Incorrect or malfunctioning oil pressure switch Replace the oil pressure switch.
• Incorrect or malfunctioning oil pressure gauge Replace the oil pressure gauge.
• Improper oil viscosity or diluted oil
• Install oil of proper viscosity for expected temperature.
• Install new oil if the oil is diluted.
• A worn or dirty oil pump Clean or replace the oil pump.
• A plugged oil filter Replace the oil filter.
• A loose or plugged oil pickup screen Replace the oil pickup screen.
• A hole in the oil pickup tube Replace the oil pickup tube.
• Excessive bearing clearance Replace the bearings.
• Cracked, porous, or plugged oil gallery Repair or replace the engine block.
• Missing or improperly installed gallery plugs Install or repair the plugs as needed.
• A stuck pressure regulator valve
• Inspect the pressure regulator valve for sticking in the bore.
• Inspect the bore for scoring and burrs.
• A worn or poorly machined camshaft Replace the camshaft.
• Worn valve guides Repair the valve guides as needed.Oil Pressure Testing
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