the armor around the combustion chambers on the OEM gasket has a tendency to crack. The cracking occurs as a result of metal fatigue caused by the head scrubbing back and forth on the block because the engine has aluminum heads and a cast-iron block. Aluminum expands at a much higher rate than cast iron, which causes the head surface to move more than the block surface. If the head gasket canÆt accommodate the movement, or lacks any built-in lubricity (such as a non-stick coating), thermal expansion and contraction can literally tear the head gasket apart as the miles accumulate. The fix is to replace the OEM head gasket with an improved and redesigned aftermarket head gasket that has stronger combustion armor, better materials and an anti-friction coating that can handle the movement.

http://www.underhoodservice.com/Article/...ts_to_fail.aspx


and what's the deal on this forum having changed? you cant just read the whole thread but only one post at a time?

And if you want to change something, then work on the background color...I cant see the words to read.

Interesting.


What? I can read the whole thread fine. <img src="/forums/images/graemlins/confused.gif" alt="" /> <img src="/forums/images/graemlins/confused.gif" alt="" />



Huh? Mine's an off green with black text. What color is the forum on your screen? <img src="/forums/images/graemlins/confused.gif" alt="" /> <img src="/forums/images/graemlins/confused.gif" alt="" />

Good read,

The author is one of my favorite tech writers and IMHO one of the best out there.

My take is all non MLS head gaskets on aluminum head engines will eventually fail. However MLS gaskets require really flat heads and very good surface finish so you need to be carefull when using them.

And opf course be carfull when adding cooling sytems sealant. Not good for partially plugged radiators.

Kevin

Good stuff...

Click on 'flat' rather than 'threaded'...I think <img src="/forums/images/graemlins/kewl.gif" alt="" />

Nice article.. Kevin, what is MLS? Also he says the solution is to install an improved aftermarket gasket. So which brand are we talking here?

The one thing I don't agree with is adding the cooling system sealer. But good with the checking of the bolt length and block threads. Same stuff Frank R's been telling us for years..

MLS = multi layer steel

It is a good article and I agree with Kevin that the author gives sound advice. He takes a very common-sense approach that is usually founded on experience coupled with good forensic skills.

I have not yet seen a 3.0L OE head gasket fail from cracked fire rings. Perhaps the author has seen more 3.0L gaskets than I have - and likely so - but I don't think this should be a problem unless there is another larger underlying problem that is the cause - such as thermal events caused by pre-ignition or detonation.

I agree with Kevin wrt the MLS gaskets. I tried them once and had immediate oil seepage because the machine shop I used does not have the ability to get a good enough surface finish. For that reason, I cannot recommend the MLS gaskets and besides, they're not needed for a 3.0L engine. The OE composite gasket works well, even with a moderate amount of boost, and it can provide a measure of sealing for etched decks that the MLS gasket cannot do - very important if heads are replaced without doing a complete rebuild including a deck cut.

The comments wrt head bolts are dead on target and extremely appropriate for 3.0L engines. If anything, the author is understating the importance of that issue, imo.

Frank

Frank if you ever up your boost and need MLS headgaskets, I know of a couple good machine shops that will do a good job. I've sent 100's of 6G72 blown heads to them without issue! They are located between Fort Mill and Concord.

Thanks - I doubt I'll increase the boost on this truck - 8 is plenty if you get the cams right. I just need to find a good forged crankshaft so I can build the replacement engine. It should have plenty of useable power when I get the torque band set right.

That Ft. Mill-to-Concord area should be full of good machine shops since it's in the heart of Charlotte Motor Speedway country. I'll be attending a function at CMS on 9/11 and will probably see a lot of machine shop reps there. I might check with you on some of them.

Frank