1996 Chevy Cavalier engine tapping

1996 CHEVROLET CAVALIER
160,000 MILES • 4 CYL • FWD • MANUAL
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MIKE T.
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I inquired earlier about this problem with my 2.4L twin-overhead cam engine concerning hydraulic lifter testing. After testing all the lifters at a repair shop(which all came back good) I removed the coilpack and bridged it to the plugs w/ sparkplug wires. With the engine running, I removed each wire 1 at a time creating a "dead cylinder". No matter which wire I removed, the tapping remained. All lifters are good, I replaced the rod bearings(out of frustration n' I was in the mood) but I can't seem to narrow down the location of this noise . I'm out of solutions and don't want to do more damage to the engine in its current condition. Any suggestions would be greatly appreciated.(Wrist pin, maybe ? Please no.)

Thanks,
Mike T.
Feb 14, 2008 at 12:14 PM
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2CARPRO JACK
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That is an all aluminum engine, they act like speakers. Are you sure the noise is valvetrain? Could it possibly be coming from the timing chain area? The valves are still moving, the lifter will still be noisy if there is no spark to the cylinder
Feb 14, 2008 at 3:50 PM
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MIKE T.
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Thanks for getting back quickly to my question. However, my 2.4L Z24 engine is not all-aluminum. The top end is (head,camshaft housings), but the block is cast iron. Dont know if this makes a difference or not. The tap goes away under load and when engine braking, but is prominent at idle and when cruising at speed. There is a hard miss sometimes when really get into it . Could I possibly have a weak valve spring?
Feb 14, 2008 at 5:40 PM
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2CARPRO JACK
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My bad on the block being iron. Could be a bad valve spring.Or maybe a valve hanging up in the giude
Feb 15, 2008 at 7:03 AM