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Was in changing some injectors in my 03 and found this next to injector 5. what can cause this to happen? can these just wear out or did something more serious cause this? I checked the push rod and its straight as an arrow.
Fatigue crack from inherent stress at the time of stamping.
Cylinder hydrolocked from over fueling and valve could not open.
Valve hitting piston from something inside the cylinder, or between the seat and valve not allowing the valve to fully close (see next one).
Lifter pump up beyond normal travel (that usually happens if the valve hangs up from carbon or stem rust) and valve hits the piston.
Someone will bring up too long pushrods, but we would have a high degree of failure or burnt valves in the community if that was true.
Fatigue crack from inherent stress at the time of stamping.
Cylinder hydrolocked from over fueling and valve could not open.
Valve hitting piston from something inside the cylinder, or between the seat and valve not allowing the valve to fully close (see next one).
Lifter pump up beyond normal travel (that usually happens if the valve hangs up from carbon or stem rust) and valve hits the piston.
Someone will bring up too long pushrods, but we would have a high degree of failure or burnt valves in the community if that was true.
So it could have been anyone of these that caused the rocker arm to fail? How do I determine what caused it to fail? And what is the most common?
If you have stock pushrods and not HD ones, I would lean more to just a failed rocker arm. High loads should bend the pushrod. I read a few people putting in a new rocker and done with the problem.
The absolute safest thing is to pull the head and see what's up.
But if that was my truck, I'd buy an under $50 borescope small diameter camera that can be hooked to a smartphone, pull the injector for that cylinder and look at the top of the piston to see if there is any damage to the piston or an object in the cylinder. Had the intake off at all?
If still worried, I'd pull the intake and check the valve with the borescope. Or not.
If it looks good in the cylinder, install a rocker and hand crack the motor two revolutions. Still good, power crank the motor with the starter jumper. If still good start it up.
Others with more damage control on the 6.0 may have a better plan.
If you have stock pushrods and not HD ones, I would lean more to just a failed rocker arm. High loads should bend the pushrod. I read a few people putting in a new rocker and done with the problem.
The absolute safest thing is to pull the head and see what's up.
But if that was my truck, I'd buy an under $50 borescope small diameter camera that can be hooked to a smartphone, pull the injector for that cylinder and look at the top of the piston to see if there is any damage to the piston or an object in the cylinder. Had the intake off at all?
If still worried, I'd pull the intake and check the valve with the borescope. Or not.
If it looks good in the cylinder, install a rocker and hand crack the motor two revolutions. Still good, power crank the motor with the starter jumper. If still good start it up.
Others with more damage control on the 6.0 may have a better plan.
I'm pulling the injector in that cylinder to replace it anyway because I had a code for a misfire in that cylinder and I do have a bore scope camera so I can check the piston that way and I definitely plan on doing that now as far as the intake goes i haven't had it off. How do I hand crank the motor?
Then there wasn’t probably something like a nut or small screw that got dropped into it, which is good. Then it’s a matter of seeing if the valve touched the piston. If there are no witness marks from the two valves on the piston, then it was just a failure of the rocker.
Pete, 87crewdually has a video showing how to install a hose to an injector tip and run compressed air. If you do that to 5 injector, it may show if it was subseptable to fuel passage and hydrolocking the cylinder, or close enough to it to stress the rocker.
Then there wasn’t probably something like a nut or small screw that got dropped into it, which is good. Then it’s a matter of seeing if the valve touched the piston. If there are no witness marks from the two valves on the piston, then it was just a failure of the rocker.
Pete, 87crewdually has a video showing how to install a hose to an injector tip and run compressed air. If you do that to 5 injector, it may show if it was subseptable to fuel passage and hydrolocking the cylinder, or close enough to it to stress the rocker.
Do you know what the link is to that video? Also could you please explain how to hand crank the motor?
Then there wasn’t probably something like a nut or small screw that got dropped into it, which is good. Then it’s a matter of seeing if the valve touched the piston. If there are no witness marks from the two valves on the piston, then it was just a failure of the rocker.
Pete, 87crewdually has a video showing how to install a hose to an injector tip and run compressed air. If you do that to 5 injector, it may show if it was subseptable to fuel passage and hydrolocking the cylinder, or close enough to it to stress the rocker.
A Question came to mind. What do I need to do if there is witness Marks on the piston from the valves?
It depends on how hard they hit. And then it's a judgment call on where you feel comfortable. Piston to valve contact has the potential to bend the valve tulips. You would see that first as a lower compression on that cylinder. Sometimes as valves get hot they will straighten back out, but no usual in my experience. But if they do there is the risk later on that the tulip will separate from the stem. Stems are typically friction welded onto the tulip. That's catastrophic with no saving the block or head typically.
On the piston side, it can just leave marks, sometimes the edge of the piston deforms at the edges and the piston to wall clearance is gone, also sometimes with the top ring captured. Another situation is there can be a stress crack in the piston that will later cause it to fracture.
But some have light marks and never have issues. Its a tough call without see it.
None of this may apply, so take one step at a time.
I did a Metadata anylsis, aka Google search, and while this site doesn’t have many, there are about a dozen instances of rocker arms breaking. One issue trends to occur with new engine assembly, and that I knew of. All the others are random, just out of the blue. Many people have just replaced the rocker and appear OK, but many stories never get the OP posting back how it went.
Theres some speculation that the valves, specifically the exhaust valve binds in the head. Possibly from carbon build up on the stem or they rust from sitting and stick. Which is interesting. The exhaust valves on the 6.0 are stainless, so it would be the head’s valve guide doing it. There also was some talk about clearance being too tight, but that should not be a concern with fair miles on the truck.
It depends on how hard they hit. And then it's a judgment call on where you feel comfortable. Piston to valve contact has the potential to bend the valve tulips. You would see that first as a lower compression on that cylinder. Sometimes as valves get hot they will straighten back out, but no usual in my experience. But if they do there is the risk later on that the tulip will separate from the stem. Stems are typically friction welded onto the tulip. That's catastrophic with no saving the block or head typically.
On the piston side, it can just leave marks, sometimes the edge of the piston deforms at the edges and the piston to wall clearance is gone, also sometimes with the top ring captured. Another situation is there can be a stress crack in the piston that will later cause it to fracture.
But some have light marks and never have issues. Its a tough call without see it.
None of this may apply, so take one step at a time.
UPDATE: I was got the old injector out of cylinder 5 and looked with my bore scope camera in the cylinder the piston was spotless not a mark on it and very clean no carbon. Almost makes me and my dad believe this motor may have been rebuilt at some point before I bought the truck it definitely doesn't look like the motor has 250,000 miles. So with that said I guess I'm good to just replace the rocker arm?
I did a Metadata anylsis, aka Google search, and while this site doesn’t have many, there are about a dozen instances of rocker arms breaking. One issue trends to occur with new engine assembly, and that I knew of. All the others are random, just out of the blue. Many people have just replaced the rocker and appear OK, but many stories never get the OP posting back how it went.
Theres some speculation that the valves, specifically the exhaust valve binds in the head. Possibly from carbon build up on the stem or they rust from sitting and stick. Which is interesting. The exhaust valves on the 6.0 are stainless, so it would be the head’s valve guide doing it. There also was some talk about clearance being too tight, but that should not be a concern with fair miles on the truck.
Had your truck sat for some time.
It sat for a month or two last summer but that's about it. I had to leave it at my uncle's house in Pennsylvania because during the move to north Carolina it broke down unexpectedly and I had to continue with the move and come back in a few months to repair it and drive it the 500 miles home but that was in October and it ran good until a few weeks ago when I had the misfire in cylinder 5.
This may or may not be the right answer, so it's your call.
When putting these motors together some had developed bent pushrods, so the stated method is to place the crankshaft in a position that will not stress the valvetrain during initial cranking. If this was recently rebuilt, it's possible that wasn't done and the rocker was stressed. You only need a slight crack for it to progress over time into a full break. If it was mine, I'd take the chance that is what happened, replace the rocker and its plastic retention clip, and see how it goes.
Considering the running time, I'm presuming its not a rust issue. Hung up from rust would leave marks.
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