what do you remove to gain access to the oil pump on 1994 Buick Park Avenue

not getting enough oil to #5 valve lifter, lifter keeps failing. low oil pressure after engine warms up

Asked by for the 1994 Buick Park Avenue
The engine bearings or oil pump may be worn out. The oil pump screen may be clogged, also. If the engine has a lot of miles or has run on dirty oil, the oil galleys may be blocked. It may be a good idea to drop the oil pan and check a bearing or two to evaluate the engine wear.
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you have to remove the oil pan and the pump is located there.