93 Z

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

Ocala93TA

iTrader: (9)

A idea to see if its the rocker move it to another cylinder , if the noise follows rocker is the problem if not could be the lifter with those miles on it

93 Z

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?

TwoFast4Lv

iTrader: (8)

Sorry to say it soulds like a rod bearing to me

Jeff400w

Do you have a broken valve spring?

93 Z

Seems like the. Valve spring is fine to me... Is a rod knock the high pitched? It's not coming from the lower end of the motor... And it only does it when its warmed up..

93 LT1 Vette

Man, no matter how many times you post this. The answer isn't going to change. Suck it up and change the lifter brother. If you keep driving it, more damage will occur.

transbird95

iTrader: (4)

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.

Ocala93TA

iTrader: (9)

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 .

93 Z

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..

Ocala93TA

iTrader: (9)

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 .

93 Z

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

05HD

Did you check the pushrods to see if they are straight? Roll them on a flat surface?