What is this tap

[spyderg0d]

B30 has been great all 280 miles on it.
Until I did a pretty hard pull with a couple limiter hits on the way home. The next time I started the car It had this loud tick/tap.
It has no drivability issues.
I did open it up and found one of the brand new lifters were squishy dead on the intake side. I didn't really check the exhaust side as I figured that 1 had to be the culprit. After getting it back together it still taps.

Anyone definitively diagnose the sound for me?
https://youtu.be/L_IgMGcoJAw

[importbanana]

sound like lifter(s) to me

[spyderg0d]

sound like lifter(s) to me

Learned me on why you think that?
How does one tell the difference between rod knock and lifter knock.

[importbanana]

crank turns at twice the speed of the cams. your tap sounds too slow for crank related noises. For my ears it fits the speed of a camshaft or lifter at idle.

In your 13 seconds video i counted approximately 70 taps. that equals to 323 taps per minute. That matches the camshaft speed. Your idle rpm is about 650rpm. Your camshaft turns at half the speed of the crank.

[spyderg0d]

That makes sense. I must have missed another dead lifter.
I'm wondering if I could have floated valves in that hard pull and it been just enough to kill lifters without bending valves.

[importbanana]

I think even the factory 25+ years valve springs should be sufficient to prevent valve float up to the stock rpm limit.

Do lifters get killed that way? I don't know, I guess when that happens the valve would more than likely be damaged and bent as well, but anyway you'll probably have to open it back up and inspect it. Didn't you have some problems with the lifters from the beginning since you replaced them? What brand did you use?

[spyderg0d]

I do believe the chip tune has a raised rev limit maybe 7200?
It certainly was in that specific time where the lifters went bad, so I'd assumed they were directly related.
Cheap ebay lifters, CNS I believe.

[spyderg0d]

I put .5 a bottle of risoline oil treatment in. .5 miles away from the house driving down the street the lifter pumped up and the sound went away in a split second.

I'm so relieved.

However the underlying issue remains. I had to have got oil starvation in the redline pull to collapse a few lifters and kill 1.

My oil pressure seems to be very healthy at the near 56-60 on cold start and 12-14 at idle when at OT, with rising oil pressure when revved. This measured on a mechanical Bosch Guage off a aftermarket obd1 filter cap.