We have a 2011 6.7 that has an extremely peculiar problem. I have never seen this before even on the trucks that have been heavily modified with a lot of power.

6.7s, these late model trucks (2011 and up), have proven to be extremely reliable and what is amazing is the emissions systems actually work. I read in one of the bulletins from Ford that it takes 93 6.7s to make the same emissions of one 7.3. The emissions systems on them work very well. This is one of those trucks that does not absolutely have to have a DPF delete on it like a 6.4. The life of the 6.4 isn’t long to begin with; but you really shorten it when you leave that DPF on.

This is an unmodified truck (stock injectors, stock turbo, stock exhaust, stock tuning) and somehow this guy broke the crank. I mean snapped half in two. We are perplexed about it.

We have the truck all apart; it is completely disassembled – motor and transmission out and the cab lifted. We try to keep things as organized as possible when we take these things apart so you don’t have to go hunting for parts and they don’t get lost or dirty. One of our little tricks is to put a piece of plywood or a pallet back here and an old rug that we get from the Cintas guys when they get too worn for use.

This truck has never even had the turbo changed. It is the factory original turbo charger. The cylinder heads all look good. There was nothing that we could see that was out of the ordinary anywhere in this truck. Everything is intact. It is only a 63k mile truck but it was making a terrible knocking noise. I was thinking that has to be a loose connecting rod, but when we pulled the oil pump there was no metal in the oil or oil filters.

If he was banging on it or tractor pulling or hooking the chains to a Dodge truck to show how much of a man he was, you would usually break the crank in the back. That is what we have seen in the past. Not on 6.7s but certainly 6.0Ls and 7.3s and the 6.4s. That would have obliterated the bottom end. We usually see the broken parts on the back. This is broken on the front.

It did spin the bearing but we don’t know if the spin was after it broke or before it broke. It lost all pressure but the truck actually ran. It actually drove off of the wrecker and into the shop but it made a terrible racket. There is no sign of abuse. The only thing that I could see in this situation that would cause this problem would be a stress crack. Usually you see spots that are dark where the crack – you could see where the crack was starting and you really don’t see that here on either of the parts. You just don’t see it. It is like a casting flaw or something like that. I don’t know if it was weakened with a cross drill. It just literally snapped. I’ve never seen anything like that. The only other thing that it could be is a harmonic in the engine.

The man claimed that there was no vibration and he wasn’t abusing it. I feel very confident that he was not abusing the engine. He said the truck was running in his driveway and it just took to banging. There was no vibration in it. The dealership said it needs a new motor and he quoted some outrageous price like $17,000. We have it apart and we are going to do it for a whole lot less than that.

We are in a quandary here about what this could be. I am not sure if it is a harmonic. If you have a bad harmonic balancer or a bad fly wheel in an engine it can send vibrations that will actually cause metal fatigue. You see it in aviation, especially in turbines and high speed engines. You get a harmonic and you can generally feel it.

We really don’t know what caused this to happen. This oil pump looks brand new. No metal has passed through this. All of the metal in the bottom on the oil pan is from the actual banging around. It is not like it is real fine power/flakes. There is no bearing metal. It is the strangest thing in the world.

I am left here to conclude that either there is a casting flaw which is very unlikely with modern production process. Maybe in 2011 they had some problems with this. What I am really asking for is feedback – any of y’all seen this kind of thing happen to your truck? I am kind of at a loss here. I don’t know why this thing would have broken like this. This thing has been meticulously cared for. The man took great care of it.

At this point there is no real conclusion. We don’t know what happened. I am going to take a precautionary measure and replace the harmonic balancer in the fly wheel with new ones just in case. We really don’t know why this broke and unfortunately the customer is out of warranty on time so Ford won’t do anything with it.

If anyone out there in the world who has had this kind of problem, I would be very interested to find out if you had any conclusions about why this might have happened to your vehicle or your engine because this is just peculiar and doesn’t make any sense.~Bill Hewitt

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