Well, I have my theory, if I ever get my heads video published.

These heads tent in the center. It's been talked about before, notice how the one set of valves are in the centerline. I have a group of blown head photos that show the leak in the center. Not by the studs or the edges, unless you have a major overheat, then they leak by the exhaust port edge. But I think these are prone to moving before they are ever installed on the motor, shown also in a SuperDuty Service video early on.

Yours appear to have machining marks.

The dirt on the turbo inlet if from the connector not sealed correctly.

 

Thanks, Jack! Sorry to be ignorant, what am I looking for or at in your explanation? I guess I need plain English, lol.

 

Hell, even the people I sent test reports to said no one would ever understand what I was saying if they weren't in the industry. I don't necessarily write plain English if English at all, which is why I'm drifting towards video. Not that they are much better. But this is some of what I have in the video.

The typical photos we see of failed head gasket tend towards this same trait. When they fail, it's in the center of the head.





Here is a motor that was torn down for bedplate leaks, and while it was being done, the owner decided to also do studs and gaskets. No failure in this area, no heavy combustion carbon deposits.




IMO, our heads tend to do this. And while we are pre-occupied with installing high strength studs for more clamping force, that will not do anything for this. I would argue if higher tension fasteners or higher strength will more margin to the yield point of the fasteners were the answer, Navistar, especially with Ford's influence, would have changed the head bolts as they did with 5 versions of heads, something never discussed.




In the past, successful integration of 4 valves per cylinder has been done with diesel, with more fasteners and with the valves in a different configuration — Two-Stroke Jimmy's from decades past.



But the modern design to get a better swirl of intake moves the valve to a different position. And Nav went with four fasteners with wide spacing. As many have speculated, the quantity of fasteners is lacking




Having the valves down the centerline also creates a weakness in the center.



Other manufactures IMO see this and utilize more fasteners and reduce the possible bending mode in the center of the heads.




Again for us with a 6.0, high strength studs will not solve this, and we see the progression to o-rings as studs have not been the "Bulletproof" answer. They are other issues that muddle the failure; surface finishing, prep, and most likely in my mind, the consistency of tensioning by the torque fastening process and tools.

But I'm speculating there may be another issue that has not been brought up. There are five different casting/part numbers over the years for our heads, the fifth being the most unique, the "20mm" heads. There are several interesting things with this head, and I don't buy the story "we just needed to change tooling in anticipation of the next model 6.4L". I think there were issues, and the changes were part of the normal "maturing" as we called it, trying to fix issues. The quantity of changes, IMO is an unappreciated story.

And I'm also drawing on my early experience within my primary company which was mainly in metal casting, along with the experience I had in the '90s when the brake rotor industry went on a study to reduce the "warping" of rotors, which had a high incidence of residual stress due to the process of casting and machining. The cast steel or iron moves on you, when machined, over time, or thermal exposure. And it can be all three. Any experienced machinist has run into some cast metal moving after machining.

Anthony Youngblood had a video that resounded within the 6.0 community, new, out of the box heads not being flat. The presumption that persisted from this is they can't machine heads, and the setup needs to support the heads better. The pattern is quite clear; the surface is cupped.





I've visited OE engine manufacturing plants, and Federal-Mogul makes a lot of internal parts. You can so see several videos that show these today, the experience of YouTube. Production manufacturing is not the level of field service machining, especially auto service machining that I equate to being a step down from pro-machinists. The engineers how to set these processes up are not going to miss keeping the parts from deflecting during machining.

So if my history with company R&D discussion of the casting group, and my experience of what TRW and the other rotor manufacturers did to decrease movement of rotors in service, Then I'm speculating we may have a stress issue in the casting. And once the new heads are machined, they are going to move. In time, in service, and every time they are machined may renew the process. Or maybe it continue. We refer to it as creep, and our failures may fall in line with the stages of creep.








After I did light abrasive cleaning with my flat plate, I used my 24" straightedge to do an elevation map of my heads, and they laid out the same as was shown in the machining video of new heads. And in fact, that trait is also shown in other pictures or images of used 6.0 heads when machined. They cup.




So without doing any more abrasive changes to the heads to alter the flatness, and already having the block resurfaced to flat, I placed tracing paper on the decks and installed the heads without gaskets to 75% of stated fastener torque. (I would have preferred to use FujiFilm, but that's expensive.) And this was the pattern left. As I showed with the line drawing, compressive forces are highest around the fasteners and the ends of the heads. That's normal around the fasteners, the area by the block threads are going to pull up in tension, just as the areas under the heads are going to push down. Bt the tracing shows the center of the head has a lower compression. We can increase that compressive force with studs while also increasing the force around the fasteners. But the ratio of compression of these different areas will mostly remain the same.





I went back and continued to rework the heads by my description of "lapping", just as I showed in the resurfacing the block decks video that is published. They are flat in the width direction. They are not perfectly flat in the longitudinal direction, but I'm OK with that. Ford also has stated not to worry, and I think they know things not published. If I know my Ford OE engineers, they have been on top of this. This is an intermediate stage for my work. The compression in the center is improved.







So how does cupping or tenting in the center get from the area of the interior of the head also sloped? If you've fastened down plastic or sheet metal on the perimeter, you may have seen distortion in the field of the object. And I think that happens here as well. You can bend the length of the head down as Ford infers, but we probably get a little stress in the center. Add that to some creep, and we are going to continue to have an issue.

The creep situation I'm speculating may be more of an issue then we realize. Remember stress, stain, temperature, time, etc. from the one slide about rotors, so that a synergistic influence. And you put that into this curve, and it could be part of the reason for repeat issues, along with the tensioning method, surface prep, etc.




Which brings me back to my question, why five different casting/part numbers, with the last 20mm heads. Relocating the injector bolt down point, and more interesting, the change in the core plug hole dimensions. My BIL used to be a pattern maker. The reason you alter these is to support the inner pattern better, less prone to move around during the casting process when the "lava" of heavy molten metal is flowing through. So it may not be a creeping issue, but if the inner core moved around it maybe some production heads are thinner in the layer of the combustion surface face and more prone to cupping. Or it may be both situations as these heads certainly creep.

But we will never know if they changed the cooling and heat-treating process to alleviate residual stress that would allow for Creep.

Mark Ihm doesn't get into until page 87, and it's just a presentation, a rotor presentation at that.


https://www.corvetteforum.com/forums...otor-intro.pdf


https://www.asminternational.org/doc...1-da34a9c1d80a


https://link.springer.com/article/10...665-012-0397-7


https://core.ac.uk/download/pdf/9554608.pdf



The reason that o-rings so far appear to do better than the head stud change is the o-rings would tension the center of the head to a higher state, more proportional. Pre-Stressing the head.

It may be the only change necessary, and the studs are not the factor they are presumed to be. Otherwise, the o-ring modification would have never seen the light of day.




But I'm just speculating, from a two-stall home garage, with no test equipment. At work we would go pretty deep in the hole speculating and it easy for me to do now. We found it helpful for finding things not obvious and for causes not related to our own parts. But you need a good yin-yang team.

In hindsight, I'm not sure I made this any easier.

 

So is o ring the heads the solution?

 

I used UCF o-ringed heads, Mahle head gaskets and my existing ARP2000 studs. I did all the physical work solo and had some help from a few guys on here with questions and procedures. I pulled the engine and took care of quite a few other issues and upgrades while in that far and don’t regret any of it.

 

Based on reports, they seem to have held up better than studs. I'll always take the perspective that it may change over time.

For my motor, I'm going to go without the o-rings, but trying to do the best I personally can in having good surfaces, which I think in the history of in-field service has been lacking, especially on the deck side.

I've thought about doing the o-rings, but I'm not expecting for this truck to have more than another 75-100k life due to rust, and I wasted too much money on a Ford reman for this chassis. This chassis has already been too expensive, so sending out good heads with only 75k on them to be fully redone and o-rings installed is a bridge too far for me. If the chassis was low rust, that could have changed my mind.

 

Cast Iron heads (all heads for that matter) concentrate heat in the center. I'm running aluminum heads whenever possible as they just shed heat a lot faster than cast.................

I see plenty of shops slicing down heads all the time and just caution that in the process they're weakening the casting and/or increasing compression.......the race car people I worked for would slice stuff but they'd also bolt these to a fixture, cook it in an oven for hours..............

O-rings work but are very tricky.....either head or block -- few machine shops get it right.

 

Except when you lose coolant integrity, then the heat and the failure is over the exhaust ports. The movement in the head center area then changes from concave to convex. And the thermal expansion of the heads in that area may stretch the head bolts past the yield point.







I agree that milling may be weakening the casting leading to a second round of blown head gaskets, which is why Nav and Ford are so hyper about the thickness measurement on this motor. They may have been aware of this all along, and for my sake, an issue addressed with the 20mm heads.

If the valves are recessed to the same degree after milling the head, the compression will not be changed since the combustion chamber is in the pistons.





.

 

Thanks for the info, Jack!

The Anthony Youngblood vídeo of the Ford heads being out of spec is kind of scary. These trucks are coming from the factory like this? My mechanic does not use o-ringed heads or I should say he did not suggest doing that. He said he has never had any come backs, except when he used an after market gasket the owner wanted.

From what I am taking from you post, my heads did not have a bad overheat and look like the average HG issues? Jack, thanks for always educating us guys who know just enough to get us in trouble!

 

Wow. I take a week off to the cottage and start catching up on my reading of various forums and can't believe what I missed.

All cast iron "seasons" to some degree. Some of this is from aging, some from how it is machined. You can actually induce stress into a casting( head, block or whatever) with the clamping force and with the type of cutter. When the manufacturing company Moore made their jig grinders(very high precision hole grinding machines and truly works of art in the shop) they used a single flute cutter when machining their castings to minimize the stress introduced prior to being scraped.

I do agree that O ringing is the best but as F350 1990 mentioned that few shops can do this well. I also find that even in standard machining a lot depends on the skill/measuring capabilities of the person running the mill.

Rob

 

It was just me going off on a wild tangent without reality.

My company in its original form was Abex, very into all railroads products as we were part of IC Industries. I remember some of the discussions about getting those products "seasoned" or stress reduced, especially the railroad wheels.

With the rotor studies, it was found that they could move 2,5 ... years in service. And moved when machined again. While we think in terms of rotor warp, it was not necessarily from heat or rapid cooling as the public believes. While post-casting heat treating was always part of the manufacturing process, along with the concern of the distribution of the matrix, the time kept in the sand showed to very important. Not unlike welding cast iron and sticking the object in the sand to let it cool slowly, letting the matrix resettle. All the rotor manufacturers were changing their methods, and when we took over Wagner around 2000 they had also changed in step with what was found a decade before.

There was a thread on Practical Machinist forum years back where a guy had machined a cast-iron disc and while on the shelf it moved on him. Other chimed in about seeing that too.

I think there's a chance these heads are creeping after machining, but where it is on the graph, god only knows.

 

So it looks like SmackDaddy preped the engine block deck surface with a hand held sanding block. Not having to pull and disassemble the engine to surface the block deck would save time and money, this being an acceptable repair.

 

Some others go a little crazy too.

 

Excited to have my truck back! Did a maiden voyage and she ran like a top towing the toy hauler.
A couple of things I noticed.
1. My mechanic used heavy duty SCA precharged coolant. That’s what he has always used... is this normal? Is this okay?
2. The loud fan did not come on while towing, it has in the past. Wonder what’s the diff? When should it come on? I now have an egt probe, what temp should I not exceed?

 

The coolant isn't an issue, unless you were running the Ford gold coolant before. If so it is a recommended to do a coolant system flush to remove the silica residue. As for the fan, are you getting above 225 F while towing? The roaring fan usually shows up around that temperature.