Ok I have tried to google and look over most all threads in here to try and find an answer to my question, my trans am has 158,000 miles on it. I hear a loud tapping sound which I believe is a lazy lifter, I am 99 percent sure that is my issue, but my question I have is how much that would fluctuate my oil pressure. At idle it likes to jump around a lot, not like 20lbs but normally running around 45 psi sometimes will drop to around 30 or so but when I gas on it pressure rises. Im just trying to see if there maybe something else I should look into as well. Never had any oil pressure issues until I heard the tapping, I know its not a rod knock or anything like that cause the car runs fine, just when it gets hot sometimes starts tapping then goes away. I already bought new LS7 lifters and ls2 lifter trays to put in the car so just trying to make sure I don't overlook anything. any input is appreciated, thank you

 

I definitely have one or more destroyed lifters, as mine is making a VERY loud clacking sound which is in cadence with valvetrain timing, not rotating assembly timing/speed.

My oil pressure gauge does not drop all that much, but, at HOT idle, the needle 'twitches' back and forth VERY rapidly for about a millimeter, in time with the clacking noise, at right around 39-41 psi, if this helps at all.

Some on here have claimed that they actually DID have spun rod bearings, and still ran OK, with 40+ psi at hot idle, due to the bearing blocking the oil port when it spun?

One even went so far as to replace his lifters thinking that was the problem, only to have the same bad noise once that was done.

I WISH there was a surefire way to KNOW (besides speed/timing, and the plug wire/injector connector disconnect method) IF certain sounds were bottom end or top end WITHOUT a full on teardown.

 

Your oil pump o-ring is probably on its way out which can cause your problems. I would change that, oil pump and timing chain while your doing your lifters. The fluctuating oil gauge could also be a bad sending unit.