Incorrect oil filter without anti-drainback feature.

Install the correct oil filter. Refer to Engine Oil and Oil Filter Replacement.

Damaged or faulty oil filter bypass valve.

Replace the oil filter. Refer to Engine Oil and Oil Filter Replacement.

Incorrect oil viscosity.

Drain and install the correct viscosity oil. Refer to Engine Oil and Oil Filter Replacement.

High valve lifter leak down rate.

Replace the lifters, as required. Refer to Valve Lifter Replacement.

Worn crankshaft thrust bearing.

1. Check the crankshaft end play. Refer to Engine Mechanical Specifications.
2. Inspect the thrust bearing and crankshaft. Refer to Crankshaft and Bearing Cleaning and Inspection.
3. Repair or replace, as required. Refer to Engine Oil and Oil Filter Replacement and Crankshaft and Bearing Installation.