What's the deal with Black Onyx Gaskets?

[Fantom]

So my truck is in the shop getting HG's (OEM of course) and studs, also had to have a valve job (cracks in the valve seats)

After reading all of the threads about Black Onyx HG's going even with studs it has me wondering, why? Heads weren't flat or possibly cracked? Is the gasket material too thin? Is there even a general consensus why they fail or are we just sticking to "don't use them, because they fail"?

[Six0~Stroker]

I think it is because they are thinner then OEM


Either way I wouldn't want to TEST them now




And, yes I will still help you but not them

[Fantom]

It's not too convincing when I tell people "don't use the black onyx gaskets" and when they ask why I just kinda look confused and yell "JUST DON'T, OKAY?!?!"

[strokinpower]

just say "unless you want to be doing this same job again in the near future , don't use them"

[Six0~Stroker]

Originally Posted by Fantom

It's not too convincing when I tell people "don't use the black onyx gaskets" and when they ask why I just kinda look confused and yell "JUST DON'T, OKAY?!?!"

I know what you mean... IIRC it is because they are thinner


Also, the "material used" might not be the best either

[Lowdown89]

I know everybody hates them, but bill at PHP runs them on his 6.0 truck and they are holding up well and he beats on the truck harder then most people would.. While I do think they might not be as good as factory gaskets I think a lot of it's in the prep work of the heads and block before you stick them on. He bought the truck with them already installed and the machine shop that did the work on the heads also installed the studs and gaskets and they are very meticulous (they did all the machine work on my 7.3 and I got the bill to show for it as well lol) and I truly think thats why some people have issues with them and some don't because the 6.0 has to be so spot on with the machine work and since the stock gasket it thicker maybe it gives just a little extra wiggle room with the machining and the black onyx gaskets expose the flaw in machine work now I could be totally wrong but that's my take on it

[Fantom]

That's pretty much what I was thinking

[Six0~Stroker]

Originally Posted by Lowdown89

I know everybody hates them, but bill at PHP runs them on his 6.0 truck and they are holding up well and he beats on the truck harder then most people would.. While I do think they might not be as good as factory gaskets I think a lot of it's in the prep work of the heads and block before you stick them on. He bought the truck with them already installed and the machine shop that did the work on the heads also installed the studs and gaskets and they are very meticulous (they did all the machine work on my 7.3 and I got the bill to show for it as well lol) and I truly think thats why some people have issues with them and some don't because the 6.0 has to be so spot on with the machine work and since the stock gasket it thicker maybe it gives just a little extra wiggle room with the machining and the black onyx gaskets expose the flaw in machine work now I could be totally wrong but that's my take on it

That might very well be the answer... SOO for 99% of owners and machinists that do not know how to meticulously work the heads OEM Head Gaskets are the way to go still




But I agree with you on your statement bud

[Lowdown89]

Oh certainly I wouldnt recommend people to run the black onyx at all, because of the difficulty in finding machine shops that really know 6.0s.. And when you can make a crap ton of power on stock gaskets with studs there really isn't a reason to run anything but OEM.... I know that's all I would use

[DoubleDpsd]

And when bill blows them I bet he puts oem on.

They were produced because there was enough of a market for them to make money off poorly designed gaskets. The market of people out there that want whats new, what others dont have... what sucks is i found posts from 2009 & 2010 on here and psn where site sponsors were selling them. Thats sucks cuz you want to believe they did their homework and that the gaskets would work.

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