6.7 Liter Powerstroke Diesel Critical Knowledge Video Series

6.7L Powerstroke Catastrophic Engine Failure

Today we are going to talk about catastrophic engine failure in a 6.7L.  This 2011 F250 with 125,000 miles has a hole in the side of the motor. It is way too early for this truck to need a motor.  But there is a very specific reason why – tuning.  Tuning absolutely kills 6.4s and 6.7s because of too much timing. We have had to put several motors in 6.7s and so far every one of them has had a tuned motor.  I beat on H&S Tuning because it is not made for the street.  I have never seen a Spartan 6.7 but I’m sure I will before it is all over.

One of the first things you notice when you pull the cab up on a 6.7 is the size of the transmission.  They made the transmission a lot bigger to handle the 850 foot-pounds of torque that this motor makes.  You will also notice two completely different cooling systems.  The two radiators manage a cooler for transmission fluid and for fuel.  The heat management system also deals with the EGR cooler so you don’t have to delete the EGR.  The EGR isn’t going to break open and send coolant down into the motor like a 6.4 and bend the #8 connective rod.  The other thing the coolant system manages is the charge air cooler.  All the hoses in earlier models for the intercooler have been replaced by a liquid system that is cooled by this radiator.  It eliminates a bunch of stuff that sat out front – the transmission cooler, the intercooler, and the power steering cooler.  All you have in the 6.7 are two coolers and an AC condenser.

So what happened to this truck?  Why did it quit running?  There is a nice hole behind the starter.  When we get the starter out, you can see the oil leak.  I bet a connecting rod came apart inside there.  Look at the kibbles and chunks!

This customer beat on this truck pretty hard.  The lifters came apart.  It appears the camshaft has broken inside this motor. The initial inspection shows some pretty FUBAR’d parts here.  I don’t think it is any fault of the part, I think the camshaft broke and the pieces got mangled up inside there.  None of this stuff is reusable.  I hope this transmission will survive a fresh motor.

Looking down into this motor with the oil pan off, it is obvious that the piston got ripped apart and it damaged the camshaft.  It actually pushed the camshaft forward in the motor and is probably what killed the lifters.  But, the initial failure was probably this piston breaking and the carnage of the connecting rod breaking off into pieces.  We found the wrist pin and all sorts of other bits and pieces in the oil pan.  This is the type of breakage that happens when the tuner salesman tells you to “put it on race tune; you can pull your trailer with that”.

Looking at the disassembled block, it is obvious that the #8 connecting rod got snapped and it went through and managed to tear everything up.  They managed to destroy the block on both sides as it went round and round on its destructive furry.  Obviously the connecting rod got snapped. But I think that came after the fact.  I think the bottom of the piston failed, which loosened the wrist pin and then everything started flinging around in there. The piston was shredded.  The engine was stressed beyond what it was designed to do by running this tuning.

To understand the effects of tuning on an engine, you have to understand what a connecting rod does.

The connecting rod is going up and down which turns the crank shaft and running the piston up and down.  You are taking the harmonic motion of the piston and you are tuning into a rotational motion which becomes the crankshaft that is attached to the transmission which goes to the drive shaft and eventually the rear wheels.  Once it comes down from the top, it pulls.  The combination of the pressure of pushing and then at higher RPM the yanking and pull – pistons in diesel engines are very heavy because of this big wrist pin –  tends to compress the rod and stretch the rod at the same time which will lead to shearing.

The problem is, when you tune this engine, you are creating a huge amount of pressure down on the connecting rod when it goes into the compression stroke.  This force is huge, but this is how it makes power by compressing the explosion.  By injecting the fuel early, you create a huge amount of pressure.  We thought it was a hydrolock, but we could find no evidence of anything that would hydrolock this engine.  It had to be pressure from combustion.

The question is, did the rod fail first or did the piston fail first.  These rods are not quite up to the type of severe duty that people are putting on them with all this tuning.  It doesn’t matter which year model truck you have, 7.3, 6.0, 6.4, 6.7, tuning will shorten the life of an engine and void the warranty with Ford and void my warranty on the work that I do.

It is obvious that the tune that is in this truck is some industrial diesel psycho tune.  It has an absolutely sick amount of power.  I asked the customer when he got the tuning for the truck what the salesman told him.  “Just put it in the race tune and you can tow a trailer”.  NO YOU CAN’T.  You are going to find the weak point in the engine.

There are three things that kill motors:

  1. Poor maintenance.  You just don’t take care of it.
  2. Abuse.  The technical term is the loose nut behind the wheel.
  3. Tuning.  The tuning strategies that they have out there for 6.4s and 6.7s are amazing. It is amazing the torque that these engines make.  They are capable of astonishing amounts of power, but it takes its toll on the engine parts.

There is only one way to really deal with a 6.7, you need to go to DP-Tuner.com.  Jody Tipton will set you up with tuning that will work with the DPF and the SCR in place and it will not void your warranty.  The tuning that is on this truck with this pipe and the DPF delete is illegal.  Frankly, I don’t think this type of tuning is necessary but people want to go fast.  But, something is going to break! Keep all that stuff on a 6.7 and go to Jody Tipton at DP-Tuner and have him do the emissions legal tuning. You will be far happier with it and you won’t kill the resale value of your truck.  ~Bill Hewitt

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