1995 Buick LeSabre Intake Tapping
8) the horizontal shaft you're asking about is a balance shaft, designed to turn at 1/2 engine speed to absorb engine vibrations. :wink:
need more description of the tapping noise.....does it sound like just one component tapping every revolution, or is it more than one noise?
you may be able to isolate it to a cylender by unpluggine one injector at a time at idle and listen to see if the noise gets louder or quieter on each cylender.
I agree to start by taking the belt off first.
Suggested Repair
Remove the serpentine belt and start the engine to see if the tapping stops; if it does, inspect belt-driven parts such as the water pump. If the noise remains, check oil pressure and isolate cylinders by unplugging one injector at a time at idle. The horizontal shaft under the intake is a balance shaft, not an oil distributor. A persistent knock after these checks may indicate an internal wrist pin.
Conversation Summary
A 1995 Buick LeSabre 3.8 has a tapping noise that seems to come from the intake manifold area. The owner replaced a head and lifters, but the noise remained and the engine otherwise ran well. Experts identified the horizontal shaft under the intake as a balance shaft and recommended removing the serpentine belt first, checking oil pressure, and isolating cylinders with injector disconnects before concluding the noise is internal, such as a wrist pin.
