What is causing this noise? (Sound clip within)
TECH Apprentice
Joined: Dec 2001
Posts: 322
Likes: 1
From: Webster, Tx, USA
Re: What is causing this noise? (Sound clip within) </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JNorris:
<strong>Unfortunately the noise does not go away after the car is warmed up, just the tone/pitch changes.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Mine is noisy all the time too. I've put about 500 miles on it since the noise started and it dosn't seem to have gotton worse. Has yours?
<strong>Unfortunately the noise does not go away after the car is warmed up, just the tone/pitch changes.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Mine is noisy all the time too. I've put about 500 miles on it since the noise started and it dosn't seem to have gotton worse. Has yours?
Re: What is causing this noise? (Sound clip within) The noise became louder after I switched to synthetic oil. I have now switched back to dyno oil and the noise is not as bad. There are times when there is no noise at all and other times it is there. The noise does not seem to be getting louder. The noise does go away after I rev the engine past 2000 rpm then will slowly return. Listen to the SOUND CLIP (1.3mb) below to hear what I am talking about.
Turn up your volume to hear it well.
Revving sound clip
Turn up your volume to hear it well.
Revving sound clip
TECH Apprentice
Joined: Dec 2001
Posts: 322
Likes: 1
From: Webster, Tx, USA
Re: What is causing this noise? (Sound clip within) That is exactly what mine sounds like. I'm checking my rod bearings for wear before I get on it hard again.
<small>[ May 03, 2002, 09:30 PM: Message edited by: RacerX ]</small>
<small>[ May 03, 2002, 09:30 PM: Message edited by: RacerX ]</small>
TECH Apprentice
Joined: Dec 2001
Posts: 322
Likes: 1
From: Webster, Tx, USA
Re: What is causing this noise? (Sound clip within) </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by patSS/00:
<strong>Rumor has it (from LS1.com) that there will be a service bulletin out this month for piston slap.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So will that help me if I'm out of the 36k mile warranty?
<strong>Rumor has it (from LS1.com) that there will be a service bulletin out this month for piston slap.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So will that help me if I'm out of the 36k mile warranty?
Re: What is causing this noise? (Sound clip within) </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by RacerX:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by patSS/00:
<strong>Rumor has it (from LS1.com) that there will be a service bulletin out this month for piston slap.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So will that help me if I'm out of the 36k mile warranty?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No idea - like I said it's just a rumor. There've been a huge number of posts about piston slap (or cold knock, whatever you want to call it) on LS1.com - do a search there to read all about it. It's pretty common. My car has it, I'm trying to figure out what to do about it (if anything) while I've still got a year left on warranty. Seems like the key thing is to figure out if you've got an overbored cylinder, or if it's "normal" piston slap. Wish I knew how to find out, without tearing down the engine.
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by patSS/00:
<strong>Rumor has it (from LS1.com) that there will be a service bulletin out this month for piston slap.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So will that help me if I'm out of the 36k mile warranty?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No idea - like I said it's just a rumor. There've been a huge number of posts about piston slap (or cold knock, whatever you want to call it) on LS1.com - do a search there to read all about it. It's pretty common. My car has it, I'm trying to figure out what to do about it (if anything) while I've still got a year left on warranty. Seems like the key thing is to figure out if you've got an overbored cylinder, or if it's "normal" piston slap. Wish I knew how to find out, without tearing down the engine.
Re: What is causing this noise? (Sound clip within) I have a 2001 Corvette. Just turned 20,000 miles two weeks ago and suddenly that noise is part of my start up when cold as well. I have been told it may be piston slap, lifters, or rocker arms. Don't know what it is but it's frustrating as heck to hear that on a $45,000 car! My car never goes to the dealer so I will probrably start with the easy stuff like replacing the roller rockers this week. Hopefully thats what it is.
Bob
Bob
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Re: What is causing this noise? (Sound clip within) PISTON SLAP IT IS!!!!
A bunch of motors have been returned and pulled out under warranty because of this tapping like sound!!!!
A bunch of motors have been returned and pulled out under warranty because of this tapping like sound!!!!
Re: What is causing this noise? (Sound clip within) WOW! It seems that the overwhelming opinion is that it is piston slap.
The noise is coming from the front of the motor behind and below the water pump. Are cylinders 1 and 2 more likely to have piston slap than the other cylinders?
What test / check can be performed to confirm the problem is piston slap?
Thanks
John
The noise is coming from the front of the motor behind and below the water pump. Are cylinders 1 and 2 more likely to have piston slap than the other cylinders?
What test / check can be performed to confirm the problem is piston slap?
Thanks
John
Re: What is causing this noise? (Sound clip within) Well I took off the ASP pulley and cranked up the car. After about 2 minutes the knocking/slapping came back. So it was not the pulley. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
I also did some more troubleshooting. With the engine running I pulled off the coil wire to #1 and the noise became very quiet if not totally gone. I went ahead and put #1 back on and the noise came back after about 1 min. I then pulled #3 and then #2 and there was very little change in the knocking/slapping sound.
What is this an indication of?
<img border="0" alt="[guns]" title="" src="graemlins/gr_guns.gif" /> 98 Z28 with knocking/slapping sound coming from the engine.
Thanks
John
I also did some more troubleshooting. With the engine running I pulled off the coil wire to #1 and the noise became very quiet if not totally gone. I went ahead and put #1 back on and the noise came back after about 1 min. I then pulled #3 and then #2 and there was very little change in the knocking/slapping sound.
What is this an indication of?
<img border="0" alt="[guns]" title="" src="graemlins/gr_guns.gif" /> 98 Z28 with knocking/slapping sound coming from the engine.
Thanks
John
