Lt1 valve tapping!!! Need help
Thread Starter
Registered User
Joined: Dec 2011
Posts: 24
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Lt1 valve tapping!!! Need help My 93 z28 developed a tapping sound on the driver side .. Sounds like a classic lifter tap. It only does it when the engine is warmed up and it does it at around 1000-1500 rpms. I'm starting to get some power loss also on acceleration. Oil pressure is around 60 under load and 40 at idle. The interesting part is, I took off the valve cover and use a screw driver to locate the tap and I found it on the #3 cylinder and I think exhaust valve.. So I loosened the nut on my rocker arm( which are crane cam 1.50 roller rockers) about a half turn then tighten it a half turn and the taping would stop. Then It would come back in about a minuet later.. So I thought maybe it's the lifter since the car has 240xxx miles on it... push rod and rocker arm seems fine. So I buy two lifters and just replace the two for #3 cylinder. Put her all back together and the tapping is still there. And when you loosen the nut a half turn and tighten it real fast it goes away but then comes back... The sound is coming from the valve spring area. Any body know what it could be? Here's a video of it from YouTube..
http://www.youtube.com/watch?v=PWPWC...e_gdata_player
http://www.youtube.com/watch?v=0TY6o...e_gdata_player
http://www.youtube.com/watch?v=PWPWC...e_gdata_player
http://www.youtube.com/watch?v=0TY6o...e_gdata_player
TECH Enthusiast
Joined: Mar 2009
Posts: 680
Likes: 7
From: Clearwater
for grins could you move the rocker arm from said cylinder to another one and see if it follows? i have only heard of rocker arm bearings falling apart and never heard what they sound like when they go bad.
Did you soak the new lifters in oil for a day or so?
is any spring cracked or broken?
if the noise goes away after you loosen and re tighten for a min or so i would say the lifter is the issue as its under preload. if it were the rocker it would always do it, same with spring. im thinking another lifter or improper install of the new lifters
is any spring cracked or broken?
if the noise goes away after you loosen and re tighten for a min or so i would say the lifter is the issue as its under preload. if it were the rocker it would always do it, same with spring. im thinking another lifter or improper install of the new lifters
TECH Veteran
Joined: Dec 2008
Posts: 4,145
Likes: 61
From: Little Rock, AR
I would carefully inspect the spring/retainer/lock and if ok I would suspect the lifter.
