General Tech Good at troubleshooting? Have a non-specific issue? Discuss general tech topics here. IF YOUR QUESTION IS SPECIFIC TO A CERTAIN MODEL, IT DOES NOT GO IN THIS SECTION.
Sponsored by:
Sponsored by: CARiD

Compression test

Thread Tools
 
Search this Thread
 
Old Sep 21, 2022 | 10:16 PM
  #1  
dagger1982's Avatar
Thread Starter
CF Beginner
 
Joined: Sep 2022
Posts: 5
Likes: 0
Default Compression test

GM 5.3 Liter V8 Vortec LC9 Engine in a 2012 Suburban. Lifter collapsed so a friend mechanic rebuilt the top half. Used a grinding/lapping compound to refresh the valve seats. Having misfires (4 and 7) so I asked him what the compression test results were. I think they are a bit wonky but would like opinions before I say anything. 164k miles
Dry test
1-160 2-210
3-212 4-170
5-212 6-175
7-200 8-150
Reply
Old Sep 24, 2022 | 4:00 AM
  #2  
oilcanhenry's Avatar
CF Monarch
 
Joined: Oct 2017
Posts: 4,605
Likes: 269
From: USA
Default

Originally Posted by dagger1982
GM 5.3 Liter V8 Vortec LC9 Engine in a 2012 Suburban. Lifter collapsed so a friend mechanic rebuilt the top half. Used a grinding/lapping compound to refresh the valve seats. Having misfires (4 and 7) so I asked him what the compression test results were. I think they are a bit wonky but would like opinions before I say anything. 164k miles
Dry test
1-160 2-210
3-212 4-170
5-212 6-175
7-200 8-150
Ideally you don't want more the 15 percent difference between cylinders, but you've got well over that with #1 and #8 vs the others. Could just be the piston rings. I'd see what a wet compression test says.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Marsh
General Tech
4
Mar 17, 2017 5:47 PM
lylesr3524
Impala
0
Apr 7, 2016 10:27 PM
tux
Silverado, Sierra & Fullsize Pick-ups
0
Nov 29, 2009 8:15 AM
jkgray80
General Tech
0
Nov 19, 2008 9:34 PM




All times are GMT -5. The time now is 11:43 PM.