This true about isx heads?

[Rawze]

(07-18-2017 )tree98 Wrote:  Had a mechanic tell me that if you take the head off your isx and it has half a million miles or more that you have to inframe it or you'll never get the head torqued down properly and you'll have problems. Any truth to this??

It sounds like that mechanic possibly had some bad experiences, or worked with someone else who did.

<-- Not giving him excuses but some other informations or poor training may have gotten twisted into what your mechanic believes. Here is some infos related to this...

* It is an unspoken rule that for any reason, if the head has to come off an ISX after the 450,000 mile mark, then the head itself should not be re-used. It is considered a discard item and costs about as much as a turbocharger. The bearings and valve seats in the head typically wear out about 2x faster than the bottom end does. The overall engine life is extended greatly if the head is replaced after this mileage on it and it has to come off anyways. My own engine was a good example of this when I inframed it at 950k miles. I could have put on a head and likely ran another 800k+ on the bottom end components. It was only the head (one injector cup that had seepage for a very long time and bearings) that were worn down.

This is the more likely reason though ...

* The main reason why any head would have to be removed on an ISX is for a failed head gasket. It is uncommon to remove the head for any other reason except maybe head itself had a failure like a spun bearing in it, etc.

It is almost always a bad head gasket that leads to its removal. Just about every single shop out there checks liner height once it comes off and thinks they are ok. They then put on a new gasket and/or even a head and the engine fails again a second time a few months later. It is NOT because they can't seat it or torque it properly, but something more sinister that gets missed.

Liner fretting is the most common reason for the initial failure and subsequent repeated failures on the head gasket to an ISX. The problem is that the procedure in the book, and when they get trained, is not thorough enough for them to correctly diagnose it. In fact, out of every single head gasket failure I have ever seen on an ISX, EVERY SINGLE TIME that the head gasket failed was because of liner fretting.

It would be EXTREMELY RARE for a head gasket to fail on one and it NOT be a liner issue aside from human error (under-torquing the bolts, damaging the gasket during install, etc). On many of the ISX head gasket failures I have seen, it was difficult to spot the underlying cause of liner fretting but it was always there and could be detected. Sometimes you have to look beyond a simple height check. In fact, a height check is not really a reliable way of detecting this at all if you ask me. A big problem is poor training in this area. A simply check of liner height is all the book/training says you need to do and is not reliable in itself for detecting liner fretting/issues. -- IT IS AN INCOMPLETE METHOD AND SHOULD NEVER BE RELIED ON IN ITSELF!!!.

Long before the head comes off though,.. pressurizing the coolant system overnight with the oil pan off will usually show the area/what cylinder caused the failure. Crushed/flattened fire rings are another sign of liner fretting too. The only way a fire ring (part of the head gasket) can get crushed/flattened is if the liner gave way and dropped down at some point under stress, causing the fire ring to flatten abnormally in the same area.

Because of this incomplete training and methods, the liner fretting gets missed way too often and the result is that it costs the truck owner tens of thousands of dollars in repeat work when their engine fails again a few months later. This is because the underlying problem got overlooked. Here is a bit more on detecting liner fretting with pictures...
http://rawze.com/forums/showthread.php?t...48#pid7648

Now put yourself in the shoes of the mechanic who does no know this and only has training via checking liner height and nothing more. His shop replaces a few head gaskets because they have failed, and the engines all do it again in a short time. He scratches his head and comes to that screwed up conclusion that you have mentioned there and tells all his friends. -- The spread of mis-information starts and becomes the norm after a while. Sad indeed when there are actual reasons and solutions to those problems out there to prevent the guy who has to foot the bill yet again when his engine fails a second time.

At the end of all this, there are some things to always keep in mind here. They are...

* After 450k miles, if the head comes of for any reason whatsoever, it is highly recommended to simply replace it instead of re-working it or even worse, simply putting it back on. This is due to the fact that it wears 2x faster than the bottom and overall engine life will be extended greatly if you do so.

* Unless someone took the engine apart and made some kind of mistake, if the head comes off because of a gasket failure, even if you had a bad delete or excess power levels set, you are guaranteed that there will be a liner fretting issue somewhere to go along with it. It can be found, but you sometimes have to look very hard to see it. In this case, this leads to the conclusion that YES, if you have any kind of head gasket failure, you are almost guaranteed that pulling the liners and counter-boring the block will follow. -- I.E. the bottom end being taken apart and an inframe before it is over with. Certainly though, it is NOT because of some voodoo alignment or torquing issues because some mechanic just simply does not understand or has poor training and has jumped to some conclusions.

Always keep that in mind and by the way,.. I am full of s%$it too.

Mis-information is everywhere in this industry. Is it more common to find than good information. Sometimes that mis-information even comes from the engine makers and OEM shops themselves. They are NOT the "word of god" so to speak and are just as infallible as anyone else. Problem is that the bulk of mechanics that get OEM/certified training have their head squarely stuck in the sand. They only generally get just enough training that the maker wants them to have so that it maximizes profit and minimizes effort. It is all done under the pretense of conformity and standardization but it is really nothing more than a mask of righteousness for them to hide behind in the end.