Work on our home remodel has taken virtually all of my spare time, but my dad and I have continued to speculate about what could be causing this noise. One thing we wished we had done when Dino got the noise to disappear the first time was swap the lifters between the suspect valve and another one. We got together a couple of times and tried to eliminate the noise again, but were unsuccessful. Dino offered to stop by again, so we took him up on the offer. He adjusted the lifter preload again with the engine running and managed to eliminate the noise again. Not too surprisingly, it was on exactly the same valve; the #6 intake valve.
We pulled the rocker and carefully examined it and the corresponding push rod. Not seeing any issues, we adjusted the #6 piston to TDC and used a spring compressor to remove and examine the spring and valve. Not too surprisingly, everything looked great.
Dino’s pretty convinced now the problem must be in the head. It’s clear that the problem is localized to the valve train and we’ve eliminated everything but the valve and guide (or potentially a crack in the head itself. We have a new head on order, so I started pulling the engine apart.
I didn’t have a lot of time tonight, but I pulled the remaining rockers and push rods as well as the side pipe and exhaust manifold. I also pulled the air cleaner and distributor. Once I drain the coolant out of the block, I’ll pull the intake manifold and head.