Leak or normal for LG header?
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 3,287
Likes: 1
From: Union City CA
Leak or normal for LG header?
Had a LG pro header installed on my 2006 A6 and now I am getting a sewning machine sound when I drive it. Not at idle but when I am moving. It is not really loud but makes a put, put like sound. It sounds like an exhaust leak but just want to hear back from other LG header cars. Thanks
Former Vendor
Joined: Aug 2005
Posts: 16,897
Likes: 412
From: Lewisville TX
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Do you feel any air leaks around the cylinder head?
What gasket are you using.
I've never had a leak with GM bolts and gaskets.
972-429-1963 or anthony@lgmotorsports.com or PM me here on the board.
What gasket are you using.
I've never had a leak with GM bolts and gaskets.
972-429-1963 or anthony@lgmotorsports.com or PM me here on the board.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 3,287
Likes: 1
From: Union City CA
Do you feel any air leaks around the cylinder head?
What gasket are you using.
I've never had a leak with GM bolts and gaskets.
972-429-1963 or anthony@lgmotorsports.com or PM me here on the board.
What gasket are you using.
I've never had a leak with GM bolts and gaskets.
972-429-1963 or anthony@lgmotorsports.com or PM me here on the board.
Had not taken it back to the installer yet. Just want to see if it is normal before I take it there. They are about 70 miles from my home. I believe they used the GM gasket and bolts.
Burning Brakes
Joined: May 2006
Posts: 1,110
Likes: 16
From: stuart fl
i have noticed the samething on mine not long after i had them installed its just like you said mine only makes the slight ticking like a leak when im moving, the only reason i really hear mine is when im riding along a wall or another quiet car is beside me
Somba master
Joined: Mar 2005
Posts: 10,554
Likes: 63
Cruise-In 7, 9 & 12 Veteran
Wounded Warrior Escort '11
St. Jude Donor '07-'08-'09-'10-'11
I have LGs, and I think they allow more of the "sewing machine" sound of the valvetrain to be heard than the stockers. I KNOW mine were done right.
GM
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Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
Exactly... there is a distinct difference between header noise and a leak. You will hear alot more noise w/ the LT headers for the reason listed above. An exhaust leak generally gets much louder under load.
Burning Brakes
Joined: Dec 2007
Posts: 1,015
Likes: 1
From: Maryland
St. Jude Donor '08
It is surprising but true, but those heavy cast iron exhaust manifolds and heat shields will insulate what is otherwise normal NVH from the engine and valvetrain geometry.
Install a set of Yella Terra's and she'll be singing like a Singer Sewing Machine on speed.
I believe what you're hearing is otherwise normal NVH that is associated with and stainless steel LT headers.
It's also important to remember to make sure that everything is retorqued to spec at the 500 mile interval as well after the initial header and exhaust installation.
Install a set of Yella Terra's and she'll be singing like a Singer Sewing Machine on speed.
I believe what you're hearing is otherwise normal NVH that is associated with and stainless steel LT headers.
It's also important to remember to make sure that everything is retorqued to spec at the 500 mile interval as well after the initial header and exhaust installation.
Drifting
Joined: Jun 2007
Posts: 1,757
Likes: 2
From: Middletown DE
It is surprising but true, but those heavy cast iron exhaust manifolds and heat shields will insulate what is otherwise normal NVH from the engine and valvetrain geometry.
Install a set of Yella Terra's and she'll be singing like a Singer Sewing Machine on speed.
I believe what you're hearing is otherwise normal NVH that is associated with and stainless steel LT headers.
It's also important to remember to make sure that everything is retorqued to spec at the 500 mile interval as well after the initial header and exhaust installation.
Install a set of Yella Terra's and she'll be singing like a Singer Sewing Machine on speed.
I believe what you're hearing is otherwise normal NVH that is associated with and stainless steel LT headers.
It's also important to remember to make sure that everything is retorqued to spec at the 500 mile interval as well after the initial header and exhaust installation.
I was about to throw on a set of Harland Sharp Rockers in hopes that it would quiet things down a little after my LG install.
Drifting
Joined: Jun 2007
Posts: 1,757
Likes: 2
From: Middletown DE
So you are saying that the Yella's do indeed increase valve train noise??? I'm wondering if that is just the case with the Yella's. My tuner runs Harland's on his ZO6, and they don't seem to make any noise. He informs me that if anything, they quiet down VT noise......That is why I am sold on them.....Now I'm not sure what to do.
Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
No... I'm saying it's really no different than my buddy's '04 Z06 w/ a slightly smaller cam, stock rockers, and comp 921s (the same spring I'm running).
Valvetrain noise is affected by many variables: cam profile, spring choice, pushrod length (correct pre-load), lifters, etc.
You wouldn't go with Harland Sharps or YTs for the noise... you do it for the valvetrain stability. A proper pedestal mounted rocker w/ trunion is far more stable than the oem setup. They prevent the rocker arms from deflecting side to side and the arm itself is much stiffer. This is especially important with high lift cams as the oem rocker arm tip can deflect at high rpm/high lift resulting in the valve not getting the full lift as ground into the cam, follow me? Instead of the valve being pushed open to the .600 lift (or whatever the lift is) as ground into the cam, the rocker arm bends some and the valve may only see .595 lift.
I mean just look at them I wish I could have a clear hood and clear valve covers 
I went with the YT ultralights because they don't have excess weight over the valve tip. Harland sharps and hte original YTs put more weight over the valve tips than oem rockers which caused some power losses at ultra high rpms.
Valvetrain noise is affected by many variables: cam profile, spring choice, pushrod length (correct pre-load), lifters, etc.
You wouldn't go with Harland Sharps or YTs for the noise... you do it for the valvetrain stability. A proper pedestal mounted rocker w/ trunion is far more stable than the oem setup. They prevent the rocker arms from deflecting side to side and the arm itself is much stiffer. This is especially important with high lift cams as the oem rocker arm tip can deflect at high rpm/high lift resulting in the valve not getting the full lift as ground into the cam, follow me? Instead of the valve being pushed open to the .600 lift (or whatever the lift is) as ground into the cam, the rocker arm bends some and the valve may only see .595 lift.
I mean just look at them
I wish I could have a clear hood and clear valve covers I went with the YT ultralights because they don't have excess weight over the valve tip. Harland sharps and hte original YTs put more weight over the valve tips than oem rockers which caused some power losses at ultra high rpms.
Last edited by Cobra4B; Mar 11, 2008 at 10:22 AM.
Drifting
Joined: Jun 2007
Posts: 1,757
Likes: 2
From: Middletown DE
Yeah, I follow you about valvetrain stability, and trust me I'm not doing them for just noise reasons.....I'm doing them for the increased lift I will get, something like going from .525 (stock) to .560ish with the 1.8's, as well as reduced friction....both equal more power. I'm not looking for a night and day difference in power but I am of the mind set that every little bit helps make power.......But, increased noise levels from the vt is a concern of mine....If they are going to sing, I might as well throw in a cam so I will atleast have an excuse + a good increase in power. 
Team Owner
Joined: Mar 2001
Posts: 25,889
Likes: 7
From: Virginia Beach
CI 3-5-6-7-8 Veteran
^ Oh... so you're going to put 1.8s in on a stock cam... gotcha. I'm running stock ratio 1.7s. If you're going to do a cam most are based on running stock ratio rockers and letting the cam specs control the lift.
I've never heard them on a stock cam'd car so I don't know what they'd sound like. I can say that my car isn't some crazy clunking machine... yes there's a sewing machine noise, but it did that even when bone stock.
That video I posted above is how my car sounds... and that's with a vented hood w/o a hood liner letting all the noise out... and I don't run fuel rail covers.
I've never heard them on a stock cam'd car so I don't know what they'd sound like. I can say that my car isn't some crazy clunking machine... yes there's a sewing machine noise, but it did that even when bone stock.
That video I posted above is how my car sounds... and that's with a vented hood w/o a hood liner letting all the noise out... and I don't run fuel rail covers.
Drifting
Joined: Jun 2007
Posts: 1,757
Likes: 2
From: Middletown DE
^ Oh... so you're going to put 1.8s in on a stock cam... gotcha. I'm running stock ratio 1.7s. If you're going to do a cam most are based on running stock ratio rockers and letting the cam specs control the lift.
I've never heard them on a stock cam'd car so I don't know what they'd sound like. I can say that my car isn't some crazy clunking machine... yes there's a sewing machine noise, but it did that even when bone stock.
That video I posted above is how my car sounds... and that's with a vented hood w/o a hood liner letting all the noise out... and I don't run fuel rail covers.
I've never heard them on a stock cam'd car so I don't know what they'd sound like. I can say that my car isn't some crazy clunking machine... yes there's a sewing machine noise, but it did that even when bone stock.
That video I posted above is how my car sounds... and that's with a vented hood w/o a hood liner letting all the noise out... and I don't run fuel rail covers.