Lt1 valve tap!!! Need help
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Lt1 valve tap!!! 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. The car is lossing power also. 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... 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[/QUOTE]
http://www.youtube.com/watch?v=0TY6o...e_gdata_player
http://www.youtube.com/watch?v=PWPWC...e_gdata_player[/QUOTE]
http://www.youtube.com/watch?v=0TY6o...e_gdata_player
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I have swapped a rocker and a pushrod with another one and that made no difference plus I have already changed out the lifters... No change... I am having power loss too I wonder if it has something to do with the valve?
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Is there oil coming out of the rocker on that cylinder? Probably would have been a good idea to change all of the lifters if they had that many miles on them since you had it apart once.
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Verdad Gallardo Try starting the car with the rocker adjusted properly unplug the spark plug while running if it goes away it could be a bad wrist pin . If it was a rod bearing you would hear the noise while its running from under the car .
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If u read my post the three times Ive posted this... U would know I have SUCKED it up and replaced the lifters.... So I'm trying to find out if anyone has experienced this same noise and it's not a lifter, brother... And 93TA I might try that, something's causing the tapping when the engine heats up to normal temp. Is that a symptom of a wrist pin? It doesn't tap at all when the engine is cold..
Yes it could happen when it warms up . The springs your running are they stock by any chance ? I know you said there was no sign of breaking of the spring . But did this noise start after running it hard ? or a quick trip to the rev limiter ? I ask because that could leave a chance of vavle float hitting the valve and cause a noise and lose power. You can check this with a compression test to see if the valve is still seating properly . Just some ideas . List any changes from stock you did to the top end that may help trying to figure what you have done .
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Well yes I did put it in first trina to shift into 2nd from 3rd so that didn't help but the tapping noise started about a week later.. Everything is stock to my knowlage except for the roller rockers... No matter how many adjustments I do to the valves it just won't go away... Thanks for your help though
