6.0 & 6.4 Ford Diesel Cylinder Heads

Cracked 6.0 and 6.4 Powerstroke Ford Diesel Cylinder Heads


We’ll make your 6.0 and 6.4 Ford diesel cylinder heads as bullet proof as we can. The following is what Ford says about your cracked heads:

Copied from AERA Tech Bulletin 2532:

‘Ford’s comment; NOTE: The cylinder head chamber area may exhibit very small “surface fissures” or “micro-cracks” during the Magnaflux process. These fissures or micro-cracks are typically located between the glow plug and the valve seats. They DO NOT extend into the coolant jacket and will not cause coolant loss or cooling system over pressurization. The presence of surface fissures or micro-cracks is not cause for replacement of the cylinder head.’

I don’t know about you but I wouldn’t feel good about putting Ford diesel cylinder heads back on my truck KNOWING they are cracked just because Ford say it’s O.K. It is true that most of the heads we see, the cracks have not gone into the cooling system……….yet. Cracks in cast iron cylinder heads grow, period. I also agree that the progression of these cracks, sometimes called propagation, will take quite a while UNLESS, it overheats again. Let me show you what happens.

Here is a picture of the typical glow plug hole to exhaust seat “micro-crack” as Ford calls it. The hole in the center is the injector hole, some of you already know this, and the small one at 4:00 below and to the right is the glow plug hole. If you agree that cracks grow, this won’t stay this small forever.


Glow Plug Fracture on ford diesel cylinder head
Glow Plug Fracture


Below is a picture of a typical seat fracture in Ford diesel cylinder heads. If you’re not familiar with these type of seat fractures they integrally cast meaning they are just part of the cast iron head. You cast the cylinder head and cut these out of the iron and you have a seat. The problem is the seat is only as strong as the cast iron. Ford and everyone else for that matter says either flame harden, induction harden etc. but that is just a surface treatment. Detroit, Cummins, Caterpillar and all the rest of the heavy duty diesels install heavy duty valve seat inserts, typically a Stellite or Hi-Chrome alloy, sometimes non-magnetic. The seats we install in these heads are a Stellite Hi-Chrome alloy seat. This is what I’ll show next.


Typical Valve Seat Fracture

Typical Valve Seat Fracture

The next picture is cast iron seat removed and counter bored for the replacement seat.

What is hard to tell from the picture is the crack is all gone.

If the valve seat is cracked beyond what we can cut out for a replacement seat, that is not a good repair by this method for the reasons mentioned earlier, cracks grow.


Old Cast Seats Removed

Old Cast Seats Removed


Below is the unfinished seat. We leave them slightly high so we can cut the valve recess to approximately .005” from finished depth.


Hardened Hi-Nickel Chrome Valve Seats

Hardened Hi-Nickel Chrome Valve Seats


Below is a picture of the seat that has been 3 angle cut (30, 37 1/2 and 60 degrees) to .005” from finished valve head recess.



machining ford diesel cylinder head

3 Angle Semi-Finish New Seats

Here is the cylinder head with the seat work done.


valve seats on ford diesel cylinder head

Valve Seats Finished to the Correct Valve Recession



All that’s left is final clean, wash and assembly.


bulletproof ford diesel cylinder head

Finished Head Ready For Assembly



We have now made these Ford diesel cylinder heads as bullet proof as possible. I don’t even think my ex-wife could kill these. If you have any questions about EGR cooler bypass, EGR valve bypass, please call.

About John Lantry

After my 4 1/2 year tour on a US Navy nuclear submarine, my parents and I bought a neighborhood Gulf gas station in Altamonte Springs (suburb of Orlando). It came with basic valve grinding equipment so I started there. After a year or so, we were doing work for a lot of the neighborhood shops. That went so well, in 1981 we moved to downtown Orlando, started building engines in 1986 and within 10 years employed 50 people. We sold the company in 2005, didn't like retirement so here I am, with 2 of my long term employees...back at the beginning. Hopefully I know more now than I did then.

Thanks for being here, John


  1. ray says:

    Does the 6.4 heads have the cracking issues in injector bores like 6.0?

  2. Ruben Banuelos says:

    Hi John.
    I wonder what kind of seat cutter you need for this hardened seats.
    I tried with my regular seat cuter and it din not cut this. It was to hard for it

    Macheld Shop Serv.

  3. Jesse Ramsey jr says:

    I’m buying a ford 6.0 diesel. 06. The owner told me it has a cracked injector cup. It runs great. 240000 miles.4500$ that a good deal and how much to make it reliable?

  4. Anonymous says:

    Ruben it looks like they are using either a rottler or a serdi seat cutter with a CBN bit.

  5. Anonymous says:

    Im sorry seat and guide machine. Also as I would like to know I am starting to see more and more cracked seats. While I do not go by what ford or Navistar says on what will pass and what wont I was wondering there is a visible hair line crack in the seat but it will not show up on a mag particle test. Why is that ? is the crack so minute the particle wont get into the crack ?

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