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Im replacing 1 fuel injector in my 2017 6.7 I have a few questions. When removing injectors do you need to release fuel pressure before disconnecting fuel line from rail to connecting tube?

Also when reinstalling the exhaust rocker can I just torque the bolts back to specs or do I need to adjust something else?
 

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No need to release pressure . generally I adjust the lash on all rockers since in there. But at least check the 1s you remove just good practice.

Sent from my ONEPLUS A6013 using Tapatalk
 

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Yeah, you need to re-set the lash on the rocker, you can't just tighten it down blind.

And, be super super careful with the wire harness connector studs on the top of the injectors, they are very soft and snap off very easily when tightening the nuts down on them.
 

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Yeah, you need to re-set the lash on the rocker, you can't just tighten it down blind.

And, be super super careful with the wire harness connector studs on the top of the injectors, they are very soft and snap off very easily when tightening the nuts down on them.
Ok thanks for the tips! How do I adjust the rockets? Is there a good tutorial on how to do it?
 

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To adjust valve lash, be it with a hydraulic or mechanical cam, you need to have the lifter on the heel or base circle of the camshaft lobe, and there are a couple of ways to get there. The first is the exhaust opening and intake closing method (EO/IC). Starting with cylinder No. 1 (usually the head that is farthest forward on the block is No. 1, or see our handy charts) with the valve cover off, rotate the engine until the exhaust pushrod begins to move upward. This is the point at which the exhaust valve is opening (EO), meaning the piston is through with the power stroke and nearing BDC, and it's about to begin the exhaust stroke. At this point, the intake valve is closed and the lifter is on the base circle of the camshaft and can be adjusted. To adjust lash with hydraulic lifters, simply grab the pushrod and back off the rocker-arm adjusting nut until you feel lash between the pushrod and the rocker arm. Turn the rocker arm adjusting nut while rotating the pushrod until there is no more play between the pushrod and the rocker arm, then tighten the adjusting nut one half turn. That's it, you're done. To adjust the exhaust lash, turn the engine over until the exhaust valve has completed its lift cycle and the intake valve is closed about three-quarters of the way (IC). Now, the exhaust lifter is on the base circle because the piston is finishing the intake stroke and about to begin compression. Set the lash on the exhaust valve and you're done. This needs to be done for each cylinder. But there is another way.
 

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Thanks a lot for the help guys, I'm confident I'll be able to do it now.
 

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The method in @terb comment is for hydraulic lifter cams, the 6.7 Cummins has a solid lifter cam and you need to set the lash with a feeler gauge. I believe the clearance for the exhaust valve is .018" and .016" for the intake.
@Gsjunk I would highly suggest you have an experienced shop do this work since it sounds like you have never done this work before. It's very critical that it gets done correctly or you could end up with a big expensive mess on your hands.
 

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The method in @terb comment is for hydraulic lifter cams, the 6.7 Cummins has a solid lifter cam and you need to set the lash with a feeler gauge. I believe the clearance for the exhaust valve is .018" and .016" for the intake.
@Gsjunk I would highly suggest you have an experienced shop do this work since it sounds like you have never done this work before. It's very critical that it gets done correctly or you could end up w
Sorry, way off on rocker clearance. 0.010” on intake and 0.026” on exhaust. If you can fit in a 0.009” or 0.027”, it’s too loose. This is not an impossible job but don’t forget if you screw up you just bought yourself multiple new parts, a tow to a shop and a pain in the rear!
 

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Sorry, way off on rocker clearance. 0.010” on intake and 0.026” on exhaust. If you can fit in a 0.009” or 0.027”, it’s too loose. This is not an impossible job but don’t forget if you screw up you just bought yourself multiple new parts, a tow to a shop and a pain in the rear!
Well, that's not exactly right either bud. And, I was going off memory, I wasn't quoting from a spec sheet.

Here is a guide, but I still recommend having an experienced shop do the job, not a good one for newbs to do.

 

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Well, that's not exactly right either bud. And, I was going off memory, I wasn't quoting from a spec sheet.

Here is a guide, but I still recommend having an experienced shop do the job, not a good one for newbs to do.

The valve cover has the clearance specs, but the problem I found today was not a bad injector as I thought. The rockers on cylinder 3 we're loose with the bridge knocked over, also the intake push rod is bent pretty bad. I got a new one coming tomorrow, hope there is no damage to the valves or piston, not sure if I should remove the head to check for valve or piston damage or just put everything back together, adjust lash and hope for the best?

Any advice much appreciated.
 

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The valve cover has the clearance specs, but the problem I found today was not a bad injector as I thought. The rockers on cylinder 3 we're loose with the bridge knocked over, also the intake push rod is bent pretty bad. I got a new one coming tomorrow, hope there is no damage to the valves or piston, not sure if I should remove the head to check for valve or piston damage or just put everything back together, adjust lash and hope for the best?

Any advice much appreciated.
oh dang man. That’s a tough break. You can always see if you can get a cheap harbor freight borescope or maybe rent one from an auto parts store to check for piston Damage without having to pull the head.
 

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The valve cover has the clearance specs, but the problem I found today was not a bad injector as I thought. The rockers on cylinder 3 we're loose with the bridge knocked over, also the intake push rod is bent pretty bad. I got a new one coming tomorrow, hope there is no damage to the valves or piston, not sure if I should remove the head to check for valve or piston damage or just put everything back together, adjust lash and hope for the best?

Any advice much appreciated.

oh dang man. That’s a tough break. You can always see if you can get a cheap harbor freight borescope or maybe rent one from an auto parts store to check for piston Damage without having to pull the head.
You'd have to pull an injector to use the bore scope.

When I had a similar issue on my engine, it was a broken valve spring, valve hit the piston and bent the pushrod.

They pulled the head to check the valve and piston and luckily no damage, just a nick where the valve kissed the piston, but the valve was ok, so all it needed was a new valve spring and pushrod and rocker arm.

So, my advice is to check the valve spring, if it's bad then you probably should pull the head to check the valve and piston.
 

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Well, that's not exactly right either bud. And, I was going off memory, I wasn't quoting from a spec sheet.

Here is a guide, but I still recommend having an experienced shop do the job, not a good one for newbs to do.

all good man it was nothing personal. Didn’t want the OP who seems a little immpressionable setting his valves that off.

and I messed up - if you can fit a 0.011” or 0.027”.... THAT is too loose.

0.009 and 0.027 SHOULD be loose
 

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Well, that's not exactly right either bud. And, I was going off memory, I wasn't quoting from a spec sheet.

Here is a guide, but I still recommend having an experienced shop do the job, not a good one for newbs to do.

Well you got that part right. Good link, however it also states if it falls within a certain range that is quite broad, NO adjustment is required. This is a link of service manual. I picked this one for easy access to anybody.
 

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No need to release pressure . generally I adjust the lash on all rockers since in there. But at least check the 1s you remove just good practice.

Sent from my ONEPLUS A6013 using Tapatalk
^ Good practi
all good man it was nothing personal. Didn’t want the OP who seems a little immpressionable setting his valves that off.

and I messed up - if you can fit a 0.011” or 0.027”.... THAT is too loose.

0.009 and 0.027 SHOULD be loose
Just because you did one valve lash don't mean you're an expert...
You do realize there's a range that is "in spec" correct? .006-.015 and .015 - .030
0.001" doesn't make an iota of difference. What do you think happens as the valves and seats wear? It doesn't need an adjustment every time it changes by 0.001".

And there's no inherent "need" to re-adjust the valve lash just because the rockers were removed to access the injectors. Nothing changes. Not a bad practice though, simply because it's easy and if the engine is near due, why not.

Also, general info, unless there is a serious or different issue, normal wear and tear results in valves that get tighter not looser.
 

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^ Good practi


Just because you did one valve lash don't mean you're an expert...
You do realize there's a range that is "in spec" correct? .006-.015 and .015 - .030
0.001" doesn't make an iota of difference. What do you think happens as the valves and seats wear? It doesn't need an adjustment every time it changes by 0.001".

And there's no inherent "need" to re-adjust the valve lash just because the rockers were removed to access the injectors. Nothing changes. Not a bad practice though, simply because it's easy and if the engine is near due, why not.

Also, general info, unless there is a serious or different issue, normal wear and tear results in valves that get tighter not looser.
Sorry if I came off sounding like a know it all. I saw no one else replying, so I figured I’d give it a try.
I just told the OP what I have learned about best practise. Set your valves how you like - your truck.

Also going to disagree that valves get tighter with time and wear as all the shops I spoke to tell me they get trucks coming in with loose valves, not tight ones.

Disagree as you will
 

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I got everything put back together and adjusted all the valves I'm sure it was due, truck seems to run better than before.. thanks for help guys
 

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Sorry if I came off sounding like a know it all. I saw no one else replying, so I figured I’d give it a try.
I just told the OP what I have learned about best practise. Set your valves how you like - your truck.

Also going to disagree that valves get tighter with time and wear as all the shops I spoke to tell me they get trucks coming in with loose valves, not tight ones.

Disagree as you will
It's all good, just providing info as well. Cheers.
On the valve thing, consider this. Loose valves are typically a symptom on hyd lifters, or maybe broken valve spring.
But picture the valve train. Spring keeps the valve shut until the cam comes around and opens it. So the valve "stem" is in tension when the spring is holding it shut, but no where near the yield tension of the stem, so it never "stretches".
But over time, the valve and valve seat wear down at the mating surface on the underside of the head. As they do, the spring pushes the end of the valve stem higher because the material at the interface is getting thinner.
End of valve "stem" gets higher, pushes down more on lifter (thee rocker arm is a teetter totter, right?). As the valve seat and valve wear, this increases, pushing down more on the lifter making it tighter.
Like I said before, there are other, less prominent things that can cause loose valves, but general wear n tear, valves get tighter in a solid lifter setup. Not conjecture. Fact.
 

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It's all good, just providing info as well. Cheers.
On the valve thing, consider this. Loose valves are typically a symptom on hyd lifters, or maybe broken valve spring.
But picture the valve train. Spring keeps the valve shut until the cam comes around and opens it. So the valve "stem" is in tension when the spring is holding it shut, but no where near the yield tension of the stem, so it never "stretches".
But over time, the valve and valve seat wear down at the mating surface on the underside of the head. As they do, the spring pushes the end of the valve stem higher because the material at the interface is getting thinner.
End of valve "stem" gets higher, pushes down more on lifter (thee rocker arm is a teetter totter, right?). As the valve seat and valve wear, this increases, pushing down more on the lifter making it tighter.
Like I said before, there are other, less prominent things that can cause loose valves, but general wear n tear, valves get tighter in a solid lifter setup. Not conjecture. Fact.
It's called valve seat recession.
 
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