head gasket
11-14-2011, 08:47 AM
#12
Originally Posted by dmelvin
I do that every time. My phone doesn't like the word Cometic.
My '02 had MLS gaskets, so it would of had to of been earlier than that for the graphite gaskets.
My '02 had MLS gaskets, so it would of had to of been earlier than that for the graphite gaskets.
I do stuff like that all of the time (sometimes I make up words and don't even realize it )For years I called Dexron ATF "DexTron", until I actually read the bottle
11-14-2011, 08:58 AM
#13
I know for sure that the factory mls's are proven though, but if you're looking for a .040 gasket, I guess that you'll have to check out other options. Guys have good luck with Cometics, but I know of at least one guy that had a Cometic leak when he installed his WCCH StageI's on his 5.3, and he fixed the problem with a set of factory mls's. The block and head surfaces were perfectly clean btw, but he still ended up doing a head swap twice
My dad (top master competition engine builder...search around here for "my pop" and you'll find some info on my pop
....but anyway, my pop loves Cometics for the race engines that he builds, and he only uses the stuff that works best. (he mentioned snipping one of the rivets on the gasket that may cause an interference problem, but Tom (tdrumm, the fella who had a Cometic leak), said that the rivets were all clear of the head and block and not causing any problems 
Hey, sometimes things go wrong for whatever reason and you have to find another avenue.Sorry to get off topic, but I just wanted to share some of my experiences and info that I have
11-14-2011, 09:11 PM
#15
I remember reading here that the 5.3's also had this issue, I believe that someone posted pics also...I'd like to know for sure if anybody has solid proof
LOL, no biggie, at least you can blame it on your phone I do stuff like that all of the time (sometimes I make up words and don't even realize it )
For years I called Dexron ATF "DexTron", until I actually read the bottle
LOL, no biggie, at least you can blame it on your phone
I do stuff like that all of the time (sometimes I make up words and don't even realize it )For years I called Dexron ATF "DexTron", until I actually read the bottle
11-14-2011, 10:47 PM
#16
Hmmm, I have a feeling that the writers of the article missed something...I find a ton of wrong stuff in the junk that I read every day. So far, I've found that I get the best info here, but unfortunately I can't remember where I read it......so I'm really just guessing
11-16-2011, 07:35 PM
#17
Hmmm, I have a feeling that the writers of the article missed something...I find a ton of wrong stuff in the junk that I read every day. So far, I've found that I get the best info here, but unfortunately I can't remember where I read it......so I'm really just guessing
11-18-2011, 07:11 AM
#20
Here is the info that Jarrod sent me in a pm, and I would take this as the gospel as he knows his **** for sure, and won't give out info unless he's sure that it's correct:
Billy, the switch over year appears to be 2001, where things could go either way. I wish I could be more certain, but it is what it is. The aluminum headed 6.0L’s got the new MLS gaskets, but the other engines just need to be looked at. The part numbers listed for Gen III’s show the composition gaskets thru 2001 and MLS for 2002 and up.
As you know, be sure to use the correct head gaskets for all of these engines because they will leak to the outside if you don't. If the head has a recess, you must use a composition gasket, but if it doesn't, you can use the MLS gasket.
Below is a random assortment of history dealing with the various blocks and heads:
* The '97-'01 head gaskets for the 5.7L engine were a composition design with elastomeric sealing ribs imprinted on them, but the imprint differed from side to side so there were right and left gaskets with two different part numbers.
* The 5.7L head gaskets were made of multilayered steel (MLS) starting in '02. They're imprinted, too, but the imprint is same on both sides so they can be used on either side of the engine. However, these MLS gaskets can't be used on the early motors because the recess in the outer edge of the heads isn't sealed by the imprint on the MLS gaskets.
There have been three different heads used on the 5.7L motors.
'97-'98 LS1 - The original LS1 heads were 10215339 or 12558806 castings that had 66.7cc chambers and nine bolts around the perimeter to hold the rocker covers on. These early heads are unique because they had a recessed area right below the No. 3 or No. 6 cylinder, so rebuilders must use the early style, composition head gaskets with them. If the later MLS gaskets are installed with the heads that have the recess, the engine will leak coolant to the outside from the recessed area in the deck surface.
'99-'04 LS1 - The LS1 switched to center-bolt rocker covers in '99, so these engines came with a new head. This 12559853 casting was used up through '01, but the 12564241 was also found on some engines beginning in '01. We're told that these heads didn't have the recessed area on the outer edge, so the MLS gasket should work okay, but the parts book calls for the composition gasket up through '01 so that's probably what you should use.
4.8L/5.3L Trucks
Both of these engines share a common aluminum head with 61cc chambers. The 12559862 casting was used from '99-'04, but the 12561706 showed up on some engines in '04, too. The 862 casting came with and without the recess on the edge of the deck surface, so rebuilders need to make sure they use the right head gasket when installing one of these heads.
From a previous post of mine:
If everything is new and you can control the Ra (roughness average) of the deck and cylinder head surfaces, then I say Cometic. If the surface finishes are already beyond your control or you’re using used components, I would recommend GM MLS gaskets. Some people have experienced sealing issues when installing Cometic head gaskets dry on blocks without a proper finish surface. While you can clean and prep the surface with 3M pads, you destroy the finish surface. People do it everyday and you can get away with it in most instances, it just doesn’t make it the correct thing to do and when someone is trying to clean up the surfaces in the vehicle, they sometimes have to do what they can.
According to surfacing experts, the recommended surface finish for a traditional composite-style soft-face head gasket in an engine with cast iron heads and block is 60-120 micro-inches Ra (roughness average). The recommended finish for the same head gasket with an aluminum head on a cast iron block is typically 20-50 micro-inches Ra. For engines with MLS gaskets, the OEM surface finish recommendations are even smoother, perhaps 20-30 or even 7-15 Ra.
According to Cometic:
Cometic recommends a surface finish of 50 RA (roughness average) or finer for a proper gasket seal. Anything rougher may conflict with the gasket design. Cometic also recommends their Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.
As you know, be sure to use the correct head gaskets for all of these engines because they will leak to the outside if you don't. If the head has a recess, you must use a composition gasket, but if it doesn't, you can use the MLS gasket.
Below is a random assortment of history dealing with the various blocks and heads:
* The '97-'01 head gaskets for the 5.7L engine were a composition design with elastomeric sealing ribs imprinted on them, but the imprint differed from side to side so there were right and left gaskets with two different part numbers.
* The 5.7L head gaskets were made of multilayered steel (MLS) starting in '02. They're imprinted, too, but the imprint is same on both sides so they can be used on either side of the engine. However, these MLS gaskets can't be used on the early motors because the recess in the outer edge of the heads isn't sealed by the imprint on the MLS gaskets.
There have been three different heads used on the 5.7L motors.
'97-'98 LS1 - The original LS1 heads were 10215339 or 12558806 castings that had 66.7cc chambers and nine bolts around the perimeter to hold the rocker covers on. These early heads are unique because they had a recessed area right below the No. 3 or No. 6 cylinder, so rebuilders must use the early style, composition head gaskets with them. If the later MLS gaskets are installed with the heads that have the recess, the engine will leak coolant to the outside from the recessed area in the deck surface.
'99-'04 LS1 - The LS1 switched to center-bolt rocker covers in '99, so these engines came with a new head. This 12559853 casting was used up through '01, but the 12564241 was also found on some engines beginning in '01. We're told that these heads didn't have the recessed area on the outer edge, so the MLS gasket should work okay, but the parts book calls for the composition gasket up through '01 so that's probably what you should use.
4.8L/5.3L Trucks
Both of these engines share a common aluminum head with 61cc chambers. The 12559862 casting was used from '99-'04, but the 12561706 showed up on some engines in '04, too. The 862 casting came with and without the recess on the edge of the deck surface, so rebuilders need to make sure they use the right head gasket when installing one of these heads.
From a previous post of mine:
If everything is new and you can control the Ra (roughness average) of the deck and cylinder head surfaces, then I say Cometic. If the surface finishes are already beyond your control or you’re using used components, I would recommend GM MLS gaskets. Some people have experienced sealing issues when installing Cometic head gaskets dry on blocks without a proper finish surface. While you can clean and prep the surface with 3M pads, you destroy the finish surface. People do it everyday and you can get away with it in most instances, it just doesn’t make it the correct thing to do and when someone is trying to clean up the surfaces in the vehicle, they sometimes have to do what they can.
According to surfacing experts, the recommended surface finish for a traditional composite-style soft-face head gasket in an engine with cast iron heads and block is 60-120 micro-inches Ra (roughness average). The recommended finish for the same head gasket with an aluminum head on a cast iron block is typically 20-50 micro-inches Ra. For engines with MLS gaskets, the OEM surface finish recommendations are even smoother, perhaps 20-30 or even 7-15 Ra.
According to Cometic:
Cometic recommends a surface finish of 50 RA (roughness average) or finer for a proper gasket seal. Anything rougher may conflict with the gasket design. Cometic also recommends their Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.