Someone we all know will have a new set of O-ringed aluminum heads soon.

 

Do tell.
Why did you choose AL.

 

It's what I'm concerned about, but I have no data either way. The machining, not the o-ring, though. I could be wrong.

When I worked part-time in an auto machine shop during college (the early 70s), there were instances of heads moving after machining. During the first 5 years of my employment at my company, I worked formulating friction materials at the Research Center located next to one of the production foundries. Most of the company's work was cast products. Occasionally we would have cross-disciplinary conferences, and there were a few discussions about creep issues, but I did not pay close attention, not my field.




I did pay attention during the mid-'90s as we had an industry-wide study on rotor causes of pulsation, signing off on $1mil worth of testing. About half the issues were due to casting methods, which were resolved by how the castings were oriented or time in the sand molds and the sand's uniformity around the cast part. Removing the residual stress. The residual stress remained after machining and would reset with re-machining. From the mid-'90s, no OE rotor manufacturer had the same issues again; the aftermarket and cheaper made rotors still could have issues. The other half of the problem was TIR and friction materials' abrasiveness, wearing the rotor's high runout sections during non-braking periods. Braking would wear the rotors evenly, and to a small extent, true the rotors, depending on friction material abrasiveness.

If that is what is going on, our trucks' normal operation, we may be in the secondary creep stage. Time, more power, higher temp, all may be accelerators to get to tertiary creep of the center. With normal operation time might get you (10 years); with more power, the forging of combustion blows might get you (50k miles); a high running temp through the mountains may get you.

Or it might just be bending stress, and eventually, the elastic deformation becomes plastic deformation. Ford might have done the study looking at what their supplier (Nav) was providing to them. Through TSBs and Recalls during my 30 years, Ford engineering goes deep when a supplier has an issue. Suppliers design the parts; Ford gives the general targets. The TSB of changing the flatness measuring to me has the feel that did that, and it was afterward that the "commonized" heads were introduced. The is nothing commonized between the 6.0 and 6.4 heads. I should not say that the gaskets bolt up the same, wider, and shorter head bolts (less stretch, but for us going to ARP does not change the modulus of elasticity, stretch).

The 6.4 gaskets do alter the coolant flow through the heads. While we have the big cooling ports in the heads and block, they are that large for the "feet" of the casting cores; the gaskets have orifices designed for the coolant flow distribution in the heads manipulated from head thermal studies. With the 6.4L, the middle area under the exhaust ports is exponentially enlarged, the back of the head flows less.

Is it the bolts, head design, or coolant flow that helps the 6.4L have very few head gasket failures? Although I would not want to have that granade of an engine.












Mark Ihm did an SAE paper on the subject, mostly about rotors, which is why I know it. It's a good read about iron castings. I presume what we have with the heads and block is compacted graphite iron.

https://documents.pub/document/tutorial-ihm.html

What I am presenting are questions, which is what I would do in my old job. The answers come after a long investigative study, one that I'm not capable of in a two-car garage, nor am I a metallurgist.

Would a different approach to heat treating for stress relief help? I think so for the bow or swale that occurs in the heads as new, but if it would do anything for the heads' tenting after the heads bolt down flat, not so sure.

Again, I may very well be way out there with these thoughts............

 

Jack, what do you not like about the 6.4? The turboproblem?


To the bigger coolant flow: I can remember times when the Mercedes Unimog 411 (engine OM636) had problems with the heat. Problem was, the coolant flow circulated too fast. Therefore head gaskets with SMALL coolant holes in the HG were used for lower coolant flow.

if we wanted to "scientifically investigate" this, we would have to check the coolant volume that flows through the engine 6.0 - 6.4


To get back to the "working" of the casting heads: heat can lead to structural changes in the heads, we all know that. We don't know exactly at which temperature which changes occur.

For me, I drive with ECT max. 98°C/208°F and EOT max. 102°C/215°C. If these values are reached, I switch the fan to full load shortly before.

 

First: please excuse my ignorance here, but as I understand the terminology: an o-ringed head has a recess machined into the head to accept the o-ring. Does anybody do, what I understand to be a fire-ring, to our 6.0s? This would be a machined recess in both head and block for the ring to go into, and thereby reducing the chance of this Creep perhaps?

Someone can go ahead and say: "shut-up stupid..." now...

 

You have the fire ring term corrrect, it seems to be done on the diesel sled and dyno engines. The creep I am discussing is the cupping, bowling, bowing, whatever you want to call it dwon the length. The secondary movement is the tenting of the heads down the center, in-between the head bolts. Are they related ... maybe, maybe not. I'm thinking of it in two different aspects 'cause I don't want to go down that rabbit hole.

 

Agree, there needs to be the proper dwell time, and the heads are different. I was just pointing out the differences, not that they would be effective to do on a 6.0L. I'm certainly not endorsing to do that.

The 6.4L may not have the head gasket issues of the 6.0L, but it has so many others in fuel delivery, lifters to name two. The FSE I know once stated every time he is called in with a 6.4L on warranty, they just find parts in the oil pan. He warned me never to consider a 6.4L.

I don't know where would be a critical point for coolant temp on a 6.0, and again if it matters at all except of course a coolant loss. It would take a scientific study if not a 1,00- people giving detailed information. A wise man (Scott) once said he wouldn't be surprised if the combustion pressure and heat to the heads deck didn't contribute to its tenting. And I agree. Nav and Ford in the documentation say over and over to not re-machine the heads and gives a thickness target. Structurally, the thickness is the primary direction for added stiffness, not width.

As I looked through my 2003 service DVD, which has all the platforms for Ford and Lincoln, it's only the 6.0 states do not machine the heads. Others either say nothing or say that Ford does not endorse machining. No other DO NOT warnings.

 

Thanks for clarifying that, Jack - I was thinking of a sort of sliding moment was also occurring besides the tenting...

 

Recently, an SAE paper by Ford engineers looked at the head gasket failing on the Focus RS motors. They showed how the gasket layers between the cylinders would move laterally and fret the sealant. I think that is part of what is happening in the center of our heads, once the gasket compression starts to compromise. The typical situation for us is we start to see pressure issues under high loading, but fine under light duty. That can be the peak combustion pressures elastically deforming the heads' center, how much pressure determines the lift. The pressure in the one cylinder then deforms the layer towards the lower pressure cylinder, and during a future cycle, the layers move opposite. Eventually, the movement compromises the seal. In our case, probably the head plastically deforms too. It's a symbolistic situation. It takes time before it becomes all or nothing, looking like 10k miles.

But this movement is what o-rings are supposed to stop, not compress the gasket tighter from my understanding. If the o-rings on the outside of the head gasket fire ring prevented full contact of the fire ring because they are too tall, the fire ring is then compromised.

It turned out that either the gasket supplier or the assembly plant substituted the Mustang gasket on the Focus engine; they both are very similar. The difference is in the block surface, a groove, or a coolant hole to move and cool the gaskets. We have coolant moving between the layers too, many engines do.

Take outs from my head gasket video as I get time to finish it and the others. I'm spending way too much time doing forum discussions rather then working on the vids.

 

Well, Jack, as usual you have filled my brain with things to think about. One thing that seems to be missing from this analysis, is data on o-ringed heads, even though the topic keeps coming back up in this discussion. Can you imagine how useful it would be to see wear, contact pressure, and lateral movement analyses of an o-ringed head? Or am I just being overly optimistic?

 

I'll mention the o-ringed heads, but it's from 30,000ft since I don't have them. If you have the money, they are a good option, and maybe the ultimate answer. I have good heads, and I don't need that expense.

Again, I'm not trying to do a series of "this is how to do a 6.0", I'm just trying to show what I'm doing to best salvage this situation with a science project slant. In a no-to-low rust state and wanting to keep this truck for a loooong time, I'd be doing differently. I'm seven years past my normal flip time as it is, I can't believe I still have this truck.

Removed the 6.0 / 6.4 head comparison for now.

 

Jack, if you'd like to borrow, for analysis, my take-off 20mm heads from my (old) truck let me know. I removed them and put them directly in the boxes that the KDD o-ringed heads came in. Let me know and I'll get them up to you.

 

Thank you for the offer, that would be interesting. Right now I am trying to do the vids of what i have and struggling to get them done, but your's would be interesting on several levels, surface finish, the flatness in both directions, maybe how much carbon is on one intake valve.

I am so far behind ...... on everything.

 

I'm sure you could find a shop to o-ring your heads.

 

I don't want to. It would ruin the science fair project.