My 2000 Blazer has a flapping sound on startup that disappears when warm. It speeds up as you rev. It does not happen on all cold starts ( even minus 20C). I am suspecting arandomly sticky lifter. Lucas oil treatment seemed to have helped but 2 days later it was back. It is not always the same loudness either. The oil pressure is good and gauge moves well when revved. Nothing is caught in any belt or fan. Tic is similar to a low oil engine tic, but oil not low and pump is working. Motor is 4.3V6. Anyone have any ideas?

 

Have you driven it when ticking? Do you notice a hesitation or power loss? Ihave a bizarre intermittent ticking as well and with mine it hesitates noticeably when driving.