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

HELP !!! -- blow-by and leak-down q?

Thread Tools
 
Search this Thread
 
Old Jul 15, 2005 | 09:29 PM
  #1  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default HELP !!! -- blow-by and leak-down q?

Hi,

If the engine has major blow-by... ie, when the oil-stick removed, it's a real cheminy.
My question is... would that be detected on a leak-down test ?
imho, it would be... and supposedly having a leak-down of under 10% for the worse cylinder doesn't add up...
What you guys think ?

Thanks,
Reply
Old Jul 15, 2005 | 09:38 PM
  #2  
closet red neck's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Jan 2005
Posts: 1,171
Likes: 0
From: Austin, TX
Default

Originally Posted by Eugenio_SS
Hi,

If the engine has major blow-by... ie, when the oil-stick removed, it's a real cheminy.
My question is... would that be detected on a leak-down test ?
imho, it would be... and supposedly having a leak-down of under 10% for the worse cylinder doesn't add up...
What you guys think ?

Thanks,
Well, my opinion is that you may have a dead cylinder. Just my opinion!!!
Reply
Old Jul 15, 2005 | 09:50 PM
  #3  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

you know what, I'm not surprised at all.
The car is low on power for what it is... and when it was last tuned, there were a few pulls done with A/F higher than 18, and the guy would still rev the thing... added lots of fuel, brought it down to 14, and the added more fuel to a decent A/F, but engine only makes 420rwhp
I don't recall engine smoking before that tune... is it possible it got dammaged on the dyno/tuning ?
Getting that checked by professionals.
Reply
Old Jul 15, 2005 | 09:55 PM
  #4  
closet red neck's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Jan 2005
Posts: 1,171
Likes: 0
From: Austin, TX
Default

Originally Posted by Eugenio_SS
you know what, I'm not surprised at all.
The car is low on power for what it is... and when it was last tuned, there were a few pulls done with A/F higher than 18, and the guy would still rev the thing... added lots of fuel, brought it down to 14, and the added more fuel to a decent A/F, but engine only makes 420rwhp
I don't recall engine smoking before that tune... is it possible it got dammaged on the dyno/tuning ?
Getting that checked by professionals.
When you first take off(first gear), does your car feel sluggish and then take off????
Reply
Old Jul 15, 2005 | 09:55 PM
  #5  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

when that tune was done, I went from a ls1 intake to a LSX-90mm + TB + TSP 85mm lid.
Reply
Old Jul 15, 2005 | 09:55 PM
  #6  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

Originally Posted by closet red neck
When you first take off(first gear), does your car feel sluggish and then take off????
hell yeah.
Reply
Old Jul 15, 2005 | 09:57 PM
  #7  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

doesn't sound too good.
Reply
Old Jul 15, 2005 | 09:59 PM
  #8  
closet red neck's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Jan 2005
Posts: 1,171
Likes: 0
From: Austin, TX
Default

Originally Posted by Eugenio_SS
doesn't sound too good.
I think that I hate to tell you but......I think you have a piston ring that laid over on you!!!
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Jul 15, 2005 | 10:10 PM
  #9  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

but if that is the case... would it be possible the leak-down to be under 10% for each cylinder, as I was told... while the engine has that much blow-by.
Reply
Old Jul 15, 2005 | 10:24 PM
  #10  
closet red neck's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Jan 2005
Posts: 1,171
Likes: 0
From: Austin, TX
Default

Originally Posted by Eugenio_SS
but if that is the case... would it be possible the leak-down to be under 10% for each cylinder, as I was told... while the engine has that much blow-by.
Well, I was told that the cylinder with the bad ring will show the most loss in compression. The leak down is to find the bad cylinder. Sure, if you pumped up that dead cylinder with air, lets say this cylinder to be under 10%. The other cylinders might be 3%. The one that yeilds the most percentage is most likely to be the bad cylinder. I'm not trying to insult your intelligence. I hope I'm understanding you correctly....LOL. I want to help you if I can!!!! I don't know...I'm just guessing!!!!!
Reply
Old Jul 15, 2005 | 10:32 PM
  #11  
Eugenio_SS's Avatar
Thread Starter
TECH Enthusiast
iTrader: (2)
 
Joined: Oct 2002
Posts: 594
Likes: 0
From: Montreal (CANADA)
Default

Originally Posted by closet red neck
Well, I was told that the cylinder with the bad ring will show the most loss in compression. The leak down is to find the bad cylinder. Sure, if you pumped up that dead cylinder with air, lets say this cylinder to be under 10%. The other cylinders might be 3%. The one that yeilds the most percentage is most likely to be the bad cylinder. I'm not trying to insult your intelligence. I hope I'm understanding you correctly....LOL. I want to help you if I can!!!! I don't know...I'm just guessing!!!!!
from what I understand stock ls1 will leakdown @ somewhere around 18% (I think)... so if the worse is 10%... that means it's in excellent condition and there is no leak whatsoever.
Now what I'm thinking is that I was BS-ed when told those #s.
Anyways, I'm having my engine checked by another shop to confirm the information I got... I can't stand BS and lies.
Reply
Old Jul 15, 2005 | 10:48 PM
  #12  
closet red neck's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Jan 2005
Posts: 1,171
Likes: 0
From: Austin, TX
Default

Originally Posted by Eugenio_SS
from what I understand stock ls1 will leakdown @ somewhere around 18% (I think)... so if the worse is 10%... that means it's in excellent condition and there is no leak whatsoever.
Now what I'm thinking is that I was BS-ed when told those #s.
Anyways, I'm having my engine checked by another shop to confirm the information I got... I can't stand BS and lies.
Well, that sound like a good idea!!!! Let me know what you find out!...O.K. I'm going to go to bed, I have to work tomorrow! Man, I've always heard that anything over 10 or 12 % is a bad thing...But that might be in the old school racing motors!!!LOL!! I maybe wrong with this ls1 thing.
Reply




All times are GMT -5. The time now is 06:03 PM.

story-0
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-1
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-2
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-3
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-4
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-5
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-6
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-7
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-8
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
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE