Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Compression numbers reason for concern?

Thread Tools
 
Search this Thread
 
Old Mar 21, 2009 | 01:25 AM
  #1  
98RedBird's Avatar
Thread Starter
TECH Addict
iTrader: (77)
 
Joined: May 2005
Posts: 2,773
Likes: 3
From: Peoria, IL
Default Compression numbers reason for concern?

Last December I picked up an 02 Camaro Z28 with only 17k miles on it. I'm in the process of doing Headers and solid motor mounts so I figured for the hell of it I'd do a quick compression test...

Well here's what I found... (Now I know that compression numbers don't mean alot, they just need to be within 10% of each other) Leakdown numbers is where I should be looking if there's a problem. But I figured with only 17k miles there really shouldn't be a problem yet... Oh, also this was on a cold motor that hasn't been run in about a week. Temps are about 40 here.

Cyl 1: 185 Cyl 2: 178
Cyl 3: 185 Cyl 4: 155
Cyl 5: 185 Cyl 6: 162
Cyl 7: 178 Cyl 8: 172

What do you guys think? Should I be alarmed by this? I'd have a hard time believing there should be a problem with the motor yet but you never know...
Reply
Old Mar 21, 2009 | 09:27 AM
  #2  
Marc 85Z28's Avatar
TECH Fanatic
iTrader: (8)
 
Joined: Sep 2005
Posts: 1,395
Likes: 6
From: MD
Default

I would recommend a wet compression test and see what numbers you get. Cylinder 4 is without question a cause for concern, and probably 6 too.
Reply
Old Mar 21, 2009 | 10:27 AM
  #3  
98RedBird's Avatar
Thread Starter
TECH Addict
iTrader: (77)
 
Joined: May 2005
Posts: 2,773
Likes: 3
From: Peoria, IL
Default

Originally Posted by Marc 85Z28
I would recommend a wet compression test and see what numbers you get. Cylinder 4 is without question a cause for concern, and probably 6 too.
Yeah, kinda what I was thinking. Once I get the exhaust done I'm probably going to let it get warmed up and do another test. I'll probably just leak down test the thing to and see what's going on.

Kinda funny though that a car with only 17k miles could be having a compression issue already. Oh well, if they are in fact that low, and it's a ring sealing issue, I guess that means I'll be stepping up from the 346!
Reply
Old Mar 21, 2009 | 01:40 PM
  #4  
hammertime's Avatar
TECH Fanatic
20 Year Member
iTrader: (1)
 
Joined: Apr 2006
Posts: 1,436
Likes: 2
From: Smithton, IL
Default

Once you run the engine and check your results warm, you might feel a little better about it. Does the car run poorly, or give you any other cause for concern? If the answer is no, then your next round of tests will likey back that up.

I suppose you could "luck out" and find a valve leaking down, and "have" to replace the heads...

Reply
Old Mar 21, 2009 | 06:55 PM
  #5  
98RedBird's Avatar
Thread Starter
TECH Addict
iTrader: (77)
 
Joined: May 2005
Posts: 2,773
Likes: 3
From: Peoria, IL
Default

Originally Posted by hammertime
Once you run the engine and check your results warm, you might feel a little better about it. Does the car run poorly, or give you any other cause for concern? If the answer is no, then your next round of tests will likey back that up.

I suppose you could "luck out" and find a valve leaking down, and "have" to replace the heads...

No, it seems to run fine. The only thing it does that concerns me is it's got a rear main leaking which could be due to excessive crankcase pressures which could mean blow-by. The two suspect cylinders are 4 and 6 (right next to each other) so I'm not ruling out head gasket issues. I would much rather it be a valve or head gasket issue because like you said... gotta replace the heads... damn lol.
Reply




All times are GMT -5. The time now is 08:40 AM.

story-0
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-1
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-2
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-3
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-4
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-5
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-6
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-7
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-8
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-9
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE