Joshboody

Recently noticed a pretty pronounced ticking (semi-knockish) sound that follows rpm. Sounds like coming more from front of the engine. What I have done so far:
- Tried listening with stethoscope, but nothing jumped out at me
- Removed belts… no change.
- Removed spark to each cylinder… no change
- Removed valve covers and didn’t notice anything loose (but I have little experience)
- Searched for exhaust leak, but don’t think so.
- *Ran the car hard which seemed to quiet it*
My thinking is a lifter… how can I confirm? Is this bad? Have a track day Sat and I’m going to run it.

Good time for a top end build with cam/heads… BUT if this could be a lower end issue, of course I should not.

Any advice would be great. I’m ok at fixing things, but suck at diagnosing issues.

2001 M6 with 100k miles… mostly HPDE car.

enoniam

I had a ticking that I couldn't pin down, until I had a lifter and/or cam lobe fail. Then had to pull the engine to have a sleeve pressed in to the damaged lifter bore...

aaronc7

Stock LS1? Take a video and slow it down to 1/8 speed, and compute how many taps per minute the tapping is occurring. Usually the tapping will be = idle speed or 1/2 idle speed, that can help you narrow down something on the crankshaft or valvetrain/camshaft related.

I recently had 2 tapping issues. First one was pronounced and didnt sound very good... it was 1/2 idle speed and I thought it was a lifter, but turned out to be a cracked piston/1 cylinder not firing.

Post rebuild I had an idle speed tapping. Turned out to be some loose bolts on the ATI damper holding the AC section on.....doh.

Joshboody

Yeah, stock LS1. I love the vid idea!

I'd think little more thorough diagnosis of the rockers should reveal any tapping lifter, right? I did kinda a quick check prob not completely checking each off lobe.