RPM dependant rapping - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old Mar 17th, 03, 05:41 AM Thread Starter
Tech Team
 
Join Date: Mar 2003
Posts: 34
Post

My '68 327 (nearly bone stock) has a hard rapping sound that seems to come in at about 2500 RPM and above. Below that it is fine. This is a freshly rebuilt engine, and the problem happenned after about 20? miles of driving.

I removed all spark plugs one at a time, trying to find the cylinder making the noise, but there was no change in the noise with any plug, so I doubt it is a bearing. Plus I took off the pan, and saw no signs of problems in the bottom end. I replaced the lifters, thinking they were broken, and the problem was not solved.

Anyone have any ideas as to what is wrong with my engine? I am going to do a compresion test and buy a stethoscope tonight. Thanks for your help.
Ryan
RyanP1 is offline  
Sponsored Links
Advertisement
 
post #2 of 5 (permalink) Old Mar 17th, 03, 07:07 AM
Senior Tech
Tom
 
Join Date: May 2001
Location: Socorro, New Mexico, USA
Posts: 574
Send a message via MSN to kausboy
Post

Possibly a broken flexplate/flywheel. Had one go on an old blazer I had -made a terrible racket!! Hope it is nothing too serious!!
kausboy is offline  
post #3 of 5 (permalink) Old Mar 20th, 03, 04:14 PM Thread Starter
Tech Team
 
Join Date: Mar 2003
Posts: 34
Angry

Here is an update to my problem.
I tested the engine's compression, and all cyllinders fell within about 20 PSI of one another from 125-145 or so. I don't think that there are any problems there. I checked the flex plate and it seemed fine, but I did not drop the transmission or anything. Could this be detonation? Plus, MGAUGHAN3 suggested the harmonic balancer. How do you tell if it is going bad? It sure doesn't feel loose on the crank, even though it is not new. Thanks again.
Ryan
RyanP1 is offline  
 
post #4 of 5 (permalink) Old Mar 20th, 03, 06:35 PM
Senior Tech
Matt Jones
 
Join Date: Jan 2002
Location: Renton, WA USA
Posts: 2,765
Post

Pulleys? Fan hitting shroud? Torque converter not engaged in pump? I'm just thinkin' out loud here...

Matt Jones
Lead Mechanical Engineer
Art Morrison Ent. Inc.
Silver69Camaro is offline  
post #5 of 5 (permalink) Old Mar 21st, 03, 04:15 AM
Senior Tech
 
Join Date: Apr 2000
Location: holliston, mass
Posts: 622
Post

Could be detonation, get a timing light with an advance, keep total timing less than 32^ as a start...

John

John...
68ragtop is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome