Soooo . . . . I figure I’d better do the nornal valve adjustment on my wife’s '95 civic (16 valve-1.5-160,000 miles). I’ve checked it every 25 or 30k, but this Summer it started to make a tapping on cold start-up, sounded like an adjustment was in order, did it all Sunday, some were tight, some were loose, but nothing really “out”. Changed the oil, felt pretty good about things, it all worked out . . . and then started it cold. Damn! Noise is still there. Sounds like it is top-end, just like a valve adjustment, so I checked them again. Right on specs, but now the tapping goes away faster than before. After a full warm-up, no noise at all (I didn’t use a stethoscope, but held my head close to the valve cover. My mechanic friend said “maybe wrist-pins”. It’s not rod knock, not deep enough. Any ideas? The noise does go away completely after warm-up, but it is still there upon start-up . . . maybe a good minute or so. Rocketman
If these are mechanical tappets then it’s just wear.
If these are hydraulic, then it’s likely that one has grown old and has difficulty expanding fully with the engorgement of oil until it gets warmed up. Probably a bit worn out or gummed up.
One more thing . . . I drove it today (stone cold, about 31 degrees in PA) and let it idle for 30 seconds, noise still there, then drifted down the hill in front of our house (in gear, no gas) . . . noise went away immediately. Upon acceleration, stared tapping again for another minute or so, then went away. No noise whatsoever on decel, lonly at idle or accel. Rocketman