I'm taking a guess on having a broken rocker, what's your guys thoughts? 08 F250 6.4l. It's got a dpf and egr delete, sct tuned with IDP custom tune. I noticed a sounds coming what seemed to be threw the intake, a popping sound, also I can hear some tapping/rattle on the passenger side valve cover area. Runs fine otherwise, buddy thought it ran to well to be broken. It's got 136k miles. But It seems to have a lot of blow by for the truck running this well. I just bought this truck at an auction, got a crazy good deal on it. So I wasn't there when this sound started. I'm leaving town for a week and won't be able to work on it, but when I get back depending on what I find out ill tear the valve cover off and look at it.
Might have a Broken rocker
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The 08 6.4's have a real bad reputation for wearing the ends of the rocker arms out. The rockesr also develop cracks at the pivot point which is why we use brand new rocker assemblies when we re-manufacture those engines. If it looks like it can be repaired, Ford sells a complete assembly that's easy to install.
I had a similar problem with a truck just like yours, except this one had a low knock when cold and once it reached a normal temperature it would go away. sometimes it would loose some power for a few seconds. took the valve covers off and we found two cracked rocker arms one on cylinder #5 and one on #8 replaced all rocker arms and problem solved. The truck had 145,000 miles on it the owner said he had never had any problems with it.
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Just replace all the rockers on that side while your at it. The assembly for all the rockers is like $150.
On the same topic, I've seen videos of some guy that repairs 6.4s running the engine with the valve covers off. It seems that too many parts must be removed to run them this way. The reason is to inspect the valve train and injector connections for leaks. Has anyone done this? Last time I did this, there was oil spray on everything in my chevy. Is it the same for the 6.4, the oil mist?
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pushrods don't typically "bust and bend" without some other issue 
Well if they are fatigued, they can bend. If they are overheated, they can creep or bend. If it was cylinder 8, then that's a regen cylinder. If those exhaust valves were getting extremely hot, then that could have been overheating the valvetrain and caused premature failure.
:dunno:
:dunno:
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all eight cylinders are regen cylinders
Oh are they? I was under the impression that the rear two cylinders were the only ones used. Well the heads are definitely lacking in coolant flow at the back side of the block. Might be a culmination of a few things. But, this is not entirely uncommon. I've read a few posts of bent pushrods.
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Usually a broken rocker arm is found along with a bent pushrod.
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