4.3 Vortec top end knock - Page 2 - Blazer Forum - Chevy Blazer Forums

2nd Gen S-series (1995-2005) Tech Discuss 2nd generation s-series (1995-2005) general tech topics here.

4.3 Vortec top end knock

  #11  
Old 01-09-2019, 05:09 PM
Mike.308's Avatar
Senior Member
Join Date: Nov 2017
Location: Poland
Posts: 576
Mike.308 is on a distinguished road
Default

If the lifter is dying, then the valves are not fully closed, so it may behave similar to a vacuum leak (like hesitation or bogging).

Depending on Your confidence of the LIM gaskets job quality, I would consider getting the lifters out for inspection. You might have some metal debris grinding Your entire engine inside... Did You notice any oil pressure drop together with the knocking effect?
 
  #12  
Old 01-09-2019, 06:08 PM
Zenith's Avatar
New Member
Join Date: Apr 2018
Location: Colorado
Posts: 83
Zenith is on a distinguished road
Default

Originally Posted by ForeverStomp View Post
The only thing I did when the valve covers were off was I checked to see if any rocker nuts came loose which they didnít but I feel as tho I may have snugged them up to much.

You may have snugged them up to much when? They have a proper torque spec, not a guess.
You may have snugged them up to much at the time you did the LIM gaskets?
Or, when you rebuilt the engine.

Again, I'm not sure if you rebuilt the engine or had it rebuilt, if you did, then I'm assuming you know how to properly adjust the valves prior to starting the engine.

If you had the engine built and you're not familiar with the valve train, I hope you didn't snug any rocker arms up this time around with the proper torquing sequence.



 
  #13  
Old 01-11-2019, 10:15 PM
New Member
Thread Starter
Join Date: Jan 2019
Posts: 6
ForeverStomp is on a distinguished road
Default

Just an update. Yes I fully built the motor myself. Those rockers r a torque to yield at 20 ft pounds so itís kinda hard to mess up but anyways. Pulled the pushrods out. Had a bent pushrod on cylinder 4 intake side. Still knocked a as I got a new one. Decided to replace that lifter Incase it got messed up however it still knocks a slight amount. I did see if any lifters were broken and all seem to compress and pump oil. But I let them soak in oil and cleaned the bores out with oil. So Iím stumped at this point. Next step it to just replace all lifter again which sucks. Since they r fairly new along with pushrods.
 
  #14  
Old 01-11-2019, 10:21 PM
odat's Avatar
Senior Member
Join Date: Sep 2013
Location: wyoming
Posts: 774
odat is on a distinguished road
Default


Push rods just don't just get bent.
Do a compression check to check for a bent valve.
If cyl 4 is low or no compression you prob have a bent valve.
Scenario I see is while you was changing lower intake gasket part of the gasket or A large chunk of carbon or something was missed and left in the intake opening in the head.
First opening of the valve it got lodged in-between the valve and seat holding the valve open.
The first stroke of the piston to TDC the valve was bent by the piston bending the push rod either then or during the next stroke
 

Last edited by odat; 01-12-2019 at 02:56 AM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
gotajam
Full Size K5 (1969-1991) GMT415 (1992-1994) Tech
2
08-21-2013 04:10 PM
jake kick
General Chat
0
04-27-2013 01:25 PM
siddhartha
Engine & Transmission
8
03-23-2012 06:47 PM
ejschultz
Engine & Transmission
2
05-23-2009 04:15 PM
90blazinchevy
General Chat
1
10-05-2007 01:52 PM


Thread Tools
Search this Thread
Quick Reply: 4.3 Vortec top end knock


Advertising
Featured Sponsors
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.