MLS Head gaskets
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MLS Head gaskets

  1. #1
    Can't re-Member 28Eliminator's Avatar
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    Default MLS Head gaskets

    Fel-Pro 1075, .041 compressed thickness.

    If a MLS gasket is supposed to be a specified thickness when installed (compressed), can someone please explain why these gaskets (30 hrs run time), are measuring less then that after removal.

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    The most likely spot for a leak, is less then the compressed height by .005 - .006. Both the head and block are showing signs of leaking. Block was square decked .015, heads were milled .020, and both still check perfect.
    I'd agree with you, but then we would both be wrong

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    Senior Member EVILFORCE's Avatar
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    BBC's are short two head bolts. Install them and it gets much better.
    No Fool Like A Old Fool is there?

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    Led
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    I didnt put caliper to mine but I seen some of the same signs on my block between the a few cylinders.

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    Quote Originally Posted by Led View Post
    I didnt put caliper to mine but I seen some of the same signs on my block between the a few cylinders.
    The "spring" to them is what makes the MLS gaskets work; ie: the "spring" is what makes it seal when the head slightly lifts and moves around. On a high output motor where there is a lot of heat, they will loose their "spring" to them. This is especially true on a 4.6 bore where the motor cannot dissipate the heat between the chambers due to the small amount of meat/webbing between the cylinders.

    What are some more specs on your motor? Bore? HP?

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    Quote Originally Posted by 28Eliminator View Post
    Fel-Pro 1075, .041 compressed thickness.

    If a MLS gasket is supposed to be a specified thickness when installed (compressed), can someone please explain why these gaskets (30 hrs run time), are measuring less then that after removal.

    Click image for larger version. 

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    The most likely spot for a leak, is less then the compressed height by .005 - .006. Both the head and block are showing signs of leaking. Block was square decked .015, heads were milled .020, and both still check perfect.
    Are they thin just between the cylinders? What's the condition of the gasket?
    I'd say you have a problem there. There should be no reason they'd be that way, especially with as mild a build as yours.
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    Quote Originally Posted by coolerman View Post
    The "spring" to them is what makes the MLS gaskets work; ie: the "spring" is what makes it seal when the head slightly lifts and moves around. On a high output motor where there is a lot of heat, they will loose their "spring" to them. This is especially true on a 4.6 bore where the motor cannot dissipate the heat between the chambers due to the small amount of meat/webbing between the cylinders.

    What are some more specs on your motor? Bore? HP?
    "Spring"? Do you mean the embossing?
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    Can't re-Member 28Eliminator's Avatar
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    Quote Originally Posted by steelcomp View Post
    Are they thin just between the cylinders? What's the condition of the gasket?
    I'd say you have a problem there. There should be no reason they'd be that way, especially with as mild a build as yours.
    Yes, only between the cylinders, were they thinner then the .041 supposed compressed thickness. They look fine, and appear to have sealed everywhere else.

    This makes absolutely no sense to me. At worse, they should be no less then the .041, under any circumstances...
    I'd agree with you, but then we would both be wrong

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    Got a call back from Fel-Pro yesterday afternoon. He told that the reason the Gasket was collapsed below the "Compressed height" between cyl's, was because I had an air pocket in the cooling system causing the head to expand and "squeeze" the gasket out of shape
    I'd agree with you, but then we would both be wrong

  10. #9
    gn7
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    Quote Originally Posted by 28Eliminator View Post
    Got a call back from Fel-Pro yesterday afternoon. He told that the reason the Gasket was collapsed below the "Compressed height" between cyl's, was because I had an air pocket in the cooling system causing the head to expand and "squeeze" the gasket out of shape
    He is not totally crazy. There is no water right where you measured it between bores on a siamesed block. Detonation will do the same thing to a head gasket. But your engine didn't seem to show signs of detonation in other cylinders.
    But heat will do that to a gasket.

    Its not so much that the base gasket is thinner, as much as the embossing is smashed flatter, annealed, and did come back.
    Last edited by gn7; 02-17-2012 at 03:45 PM.
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    Is the black coating on the gasket still there between the cylinders where the gasket is measuring thin?

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    Quote Originally Posted by gn7 View Post
    He is not totally crazy. There is no water right where you measured it between bores on a siamesed block. Detonation will do the same thing to a head gasket. But your engine didn't seem to show signs of detonation in other cylinders.
    But heat will do that to a gasket.

    Its not so much that the base gasket is thinner, as much as the embossing is smashed flatter, annealed, and did come back.
    I can only assume that an Aluminum head motor would be even worse. Are the Cometic's any more resilient to the crushing? This is really disappointing. Cometic makes some very thick MLS Head Gaskets, and I would think there has to be some expandability/resiliency for expansion and contraction, especially at the extreme thickness's of some of them..

    Maybe I should just a $29 NAPA head gasket and call it good
    I'd agree with you, but then we would both be wrong

  13. #12
    gn7
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    Quote Originally Posted by 28Eliminator View Post
    I can only assume that an Aluminum head motor would be even worse. Are the Cometic's any more resilient to the crushing? This is really disappointing. Cometic makes some very thick MLS Head Gaskets, and I would think there has to be some expandability/resiliency for expansion and contraction, especially at the extreme thickness's of some of them..

    Maybe I should just a $29 NAPA head gasket and call it good
    Thats the job of the embossing.

    Personally, for less than blown applications, I still like the Fel Pro performance line over the cometic/Fel Pro MLS. They are easier on the aluminum heads, and I have ran 12 lbs of boost on 9 to 1 compression without failure. They are way more forgiving to block and head maching, and they are cheaper. I don't use Cometic/FelPro MLS unless I have to.
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    Quote Originally Posted by WETTE VETTE View Post
    Is the black coating on the gasket still there between the cylinders where the gasket is measuring thin?
    Not really.. most of it is gone off the gasket, but some is still there, and appears to have been transferred to the Head and Block for the most part..
    I'd agree with you, but then we would both be wrong

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    so gn7 do you think or feel it would be safe to run a felpro performance line head gasket in a bbc with 13.5 to 1? and if so, what about nitrous on top of it? I personally went with the mls because of the high comp and nitrous, I thought of it as insurance, but I might need to take a head off and am not sure if it's a problem with the mls gasket or not. Needless to say they are pricey lil fockers! and if I could be safe with the performance line, then all the better.

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