Ford 6.7 power stroke crankshaft breakage.

[Chris142]

Place I work at has 20 or so trucks with this engine. 2 have suffered broken crankshafts. One with 170something and the other with 244k.

Seems to be enough of them breaking that they show up on an internet search.

Wonder why they are breaking? Junk parts? Balance issue? 800+ ft lbs of tq from a 6.7L engine?

 

[wwillson]

Have any of them been 'tuned'?

 

[Chris142]

Have any of them been 'tuned'?

None of ours. All oe stuff including all filters every 5k

 

[bullwinkle]

Where do they break? In the middle, or at the ends? I would think middle would be metallurgy, ends might be a balance issue.

 

[oggb]

Wonder why they are breaking? Junk parts? Balance issue? 800+ ft lbs of tq from a 6.7L engine?

It's a Ford. The answer is "yes".

 

[Jimmy_Russells]

What year(s) are they?

 

[Boomer]

Fix Or Repair Daily!

 

[Chris142]

What year(s) are they?

13-14

 

[Chris142]

Where do they break? In the middle, or at the ends? I would think middle would be metallurgy, ends might be a balance issue.

Right @ the timing cover.

 

[mcdonnell]

A broken crankshaft is not a common occurrence. Cranks can break due to a casting or forging flaw but this is very rare. ... Usually a crank will break because of another failure. In a diesel engine the amount torque created during a failure such as a spun bearing can cause a crank to snap.
All diesel crankshafts are heat treated. Some diesel cranks are nitrided. Nitriding is a process that introduces nitrogen into the surface of the steel at an extremely high temperature. This heat treating is done to increase wear resistance, improve fatigue and obtain a high surface hardness. Because of this process the crankshaft is extremely hard but also brittle. When an engine has a bearing failure, the excessive clearance can cause the crank to have a “jump rope” effect inside the engine. The crankshaft can bend severely or even break in some cases. In cases where a nitrided crankshaft is bent, it is usually not recommended to straighten. Attempts to do so could cause in internal and external cracks which would result in another crankshaft failure.
from internet

 

[mcdonnell]

I'm never buying a diesel

 

[Jimmy_Russells]

Bizarre. Other than some early turbo issues the 6.7L has been a pretty reliable engine.

 

[bullwinkle]

Not a good problem to have, the only other diesel I heard having broken crank trouble was the GM 6.2/6.5 nodular iron crank, and it usually took a lot of miles to happen (I had a 6.2 with 300K on the original one). First I heard of the Dmax ones breaking-sounds like ANOTHER reason to bail on the diesel bandwagon.

 

[bdcardinal]

I have seen 2 in my time here. Both were early build trucks. I will dig through my phone to find the pictures. Both trucks still ran. They cracked the crank but still turned.

 

[mattd]

I have heard of this but have never seen it first hand. It isn’t common.

the duramaxes usually break them from increased power. It doesn’t take much, either. It is far more common compared to the 6.7L.

Chris what were the hours on those trucks? Do either of those trucks pull a trailer or do the drivers lug the engine at all? Easy to do some times.

 

[mcdonnell]

in the video 1 reason is the firing order 1 2

 

[Chris142]

I have heard of this but have never seen it first hand. It isn’t common.

the duramaxes usually break them from increased power. It doesn’t take much, either. It is far more common compared to the 6.7L.

Chris what were the hours on those trucks? Do either of those trucks pull a trailer or do the drivers lug the engine at all? Easy to do some times.

They have auto transmissions. Dunno how you could lug one. They are work trucks. The F550 weighs 16k. May occasionally pull a small trailer. Usually a tacpot that does not weigh much. I can lift the tongue by myself.

 

[ctechbob]

They have auto transmissions. Dunno how you could lug one. They are work trucks. The F550 weighs 16k. May occasionally pull a small trailer. Usually a tacpot that does not weigh much. I can lift the tongue by myself.

LOL, I dunno about that. Ford and their transmission programming is funky to say the least. I'm sure its different on the diesels, but if I let it, the programming on my Ranger will let that 10R80 lug the poor 2.3L down to below 1500rpm in 6th gear putting through the neighborhood.

 

[mattd]

They have auto transmissions. Dunno how you could lug one. They are work trucks. The F550 weighs 16k. May occasionally pull a small trailer. Usually a tacpot that does not weigh much. I can lift the tongue by myself.

The TCM likes to hold 6th gear at Low RPM (down to 1000 RPM) and doesnt downshift unless you give it more than necessary throttle (my personal opinion). I lock mine out of 6th unless I plan on traveling over a certain speed. Granted the ECM limits fuel progressively until about 1400 RPM, but still don’t like to lug it.

 

[sarafino]

I knew someone with 2012 6.7 Powerstroke that had a crankshaft break. Completely stock and had approximately 180k miles on it. We searched online at the time it happened and found other reports of completely stock 6.7's with the same failure at higher mileage. Could be a random defect from whoever forges their crankshafts.