no oil pressure in top end of motor lifters are very noisey on 2002 Saturn L100

could it be the oil pump ?

2 answers
yes have the oil pressure ck'd with a oil pressure gauge
Test the engine oil pressure. It should be 50-80 PSI at 1000 RPM.

2. Check for a loose timing chain.

3. Check for a ruptured engine oil filter. The pieces can get sent through the oil passages