My vehicle is a 1998 B3500 passenger van with 5.2L engine and 89,000 miles. I just returned from 4,000 mile trip. Two days ago, after heavy acceleration, the oil pressure dropped to zero and the valve lifters began clacking. After quickly stopping, I checked the oil level and it read about 2 quarts too high. I had a quick-lube do an oil change and pressure returned to and stayed in normal operating range. Yesterday, about 1,000 miles farther on, the same thing happened, again after heavy acceleration. Another oil change and I was able to get the rest of the way home with normal oil pressure.

It seems like oil from the top end of the engine is accumulating in the oil pan during acceleration typical of the downshifts required during climbing and passing. Eventually, the overfill condition causes the oil pump to stop moving oil through the engine. Draining and refilling the engine oil alleviates the issue. Is this even possible? If so, what would the likely problem(s) be?

 

Actually it's just the opposite. The drain holes in the heads are clogged and the oil is not draining back into the pan fast enough. This is also why the oil reading was too high. You (or someone) must've checked the level before the oil drained back down. This would've given the false impression that the level was low so oil was added, and that's how you ended up with too much.

To fix it you will have to remove the valve covers and clean out the drain holes. Warm the engine and then allow a long time for the oil to drain or you will end up with a big oil spill when the valve covers are removed.