Acceptable Cracks in Cylinder Heads?

Keith Browning · February 23, 2012

I have not run into this until now... a 6.4L that melted a piston but sustained no other damage. Cleaned the heads and the affected cylinder has a crack from the glow plug bore extending to one intake and one exhaust valve. According to the HotLine and the WSM this is acceptable... they define these as "microcracks." I don't feel good about this. Am wondering if any of you have run into this and what your experience was.

For some reason I cannot connect to any videos from Ford... see this video if you can:m

multimedia.ford.com/seopts/wsm/cylinderheadflatness.wmv

Keep in mind this head was not magnafluxed and the crack is easily visible with the naked eye.

Here is what the HotLine said:

Quote:
Keith, Small cracks in this location are normal and do not require cylinder head replacement. This information can be found in the cylinder head cleaning and inspection procedure(online WSM 303-01C). This is the note from step 3 of the procedure, NOTE: The cylinder head combustion chamber area may exhibit very small 'surface fissures' or 'microcracks' during a Magnaflux inspection process. These surface fissures or microcracks 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 overpressurization. The presence of surface fissures or microcracks is not cause for replacement of the cylinder head.

lmorris · February 23, 2012

Been there, done that. Got the same response. Two sets of heads with this issue, never had any issues after repair.

Brad Clayton · February 24, 2012

I think the idea is complete bull shit. I would bet if it were their own vehicle they would be singing a different tune. I have almost had enough of the crap we are being forced to wade thru. What is policy today will be totally different tomorrow and visa-versa. I have only ran into one head with these cracks and I replaced it!!

Bruce Amacker · February 24, 2012

IH says to replace them if cracked on MaxxForce 7 (PSD 6.4).

From ISIS:

6. Spray dye penetrant on lower deck (gasket surface) of cylinder head and let dry for 5 to 15 minutes.

7. Wipe dye off cylinder head surface.

8. Spray developer on lower deck (gasket surface) of cylinder head and let dry for 5 to 15 minutes. Cracks show up as purple lines against white developer.

CAUTION:

To prevent engine damage, install a new cylinder head if cylinder head is cracked.

You make the call.

Posted Image

Keith Browning · February 24, 2012

Unfortunately Bruce, I cannot make the call under warranty. You do know that everything about this repair requires prior-approval right?

Bruce Amacker · February 24, 2012

Oh, yes, I am aware of all that, but in the OP you didn't specify whether it was a warranty fix or not, and whether it is or not does not affect my opinion. I just wanted to put my two cents in (and IH's).

If FMC wants you to pay you to put a cracked head on, then put a cracked head on, it's as simple as that. I would not want to be the cust in this situation.

Posted Image

What do you think the original problem was? Overfueling injector? I talk about this in my classes regularly- it would be nice to know if STFT was wacked out for a period of time before the piston fried. I'd almost bet on it......

DieselD · February 24, 2012

I have had that on lots of 6.0s and several 6.4 engines. I got heads each and every time no matter what the hotline response was. I had to argue with them a few times both over email and on the phone before they would say "replace" the head.

cracks in cylinder heads no matter how small are unacceptable in my book

Keith Browning · February 24, 2012

Okay, the cracks extend to the valve seat and is much easier to see with a picture than with your eyes. Should done this from the start - my bad. None the less I escalated this and called the Gents in Dearborn who now agree that the head requires replacement... re-ran the cost cap and updated the file and printed it out.

Bruce, the root cause here was an injector that was over fueling. The short term fuel trim was +19, Relative compression -9 and manual compression 305 PSI. The piston is also melted in the shape of the injector pattern, the cylinder is glazed... where it isn't scored from the piston. Your bet would have paid off if you put money on it. This all shows that an engine failure is not always catastrophic in nature. With the calibration this truck was running I would have expected the check engine light and engine de-rate to have been triggered much sooner.

Nedless to say that the "acceptable cracks" in cylinder heads need to be fully scutinized.

lmorris · February 28, 2012

Mine were never that bad. That should be a no brainer for replacement no matter what hotline says. I usually get management involved in those calls though.

Keith Browning · February 28, 2012

Mine were never that bad.

Perhaps that is the basis of my reason to starting this topic. I mean, a crack is a crack right? A crack no matter show small will likely grow and the cracks in my picture started out small too!

DieselD · February 29, 2012

Originally Posted By: lmorris

Mine were never that bad.

Perhaps that is the basis of my reason to starting this topic. I mean, a crack is a crack right? A crack no matter show small will likely grow and the cracks in my picture started out small too!

EXACTLY! This is what baffles me on fords answer that those small cracks are acceptable. I mean really? Its not going to get bigger? Posted Image

rlchv70 · March 2, 2012

The cracks actually start at the exhaust seat. There's not really any place for them to propagate to, so they don't hurt anything.

Keith Browning · March 2, 2012

The cracks actually start at the exhaust seat. There's not really any place for them to propagate to, so they don't hurt anything.

That's all well and good and that is pretty much what the fellas at Ford are saying but I still have a question: Would/could a crack in the valve seat eventually lead to a burnt valve?

cbriggs · March 3, 2012

Yes. A crack will create a leak, and in turn burn the valve.

Keith Browning · March 3, 2012

Well the job is complete and the truck is running just dandy. Hope it stays that way. The couple that owns the truck had stopped in while it was completely apart, cab in the air and all. I love the shock and awe the scenario brings... cell phones snapping pictures and lot's of questions. At least when this happens they understand the scale of the repair and why the truck is laid up fro a couple of weeks.

Mikill · March 5, 2012

It amazes me how many things are acceptable on this engine. You know things aren't gonna be good when Ford says that a noticeable ticking noise will be heard after the first oil change.

lmorris · November 6, 2013

Have one currently that is back again for smoke and the coolant is purging out the degas, just did headgaskets a week ago. Seems to happen when they pull their trailer. This started as an enhanced long block because they melted down one piston. The new water pump impeller spun on the shaft and it ran hot. Fixed the pump issue and was good for a month, then the degas purging started. The last time I had the heads off it had a crack by an exhaust valve but not through the seat. I let it go, now its back blowing out the coolant again. Sadly I can't remember which head it was so I get to take them off AGAIN.