Weird noise from 6.4L...what could it be?

[Extended Power]

It's my father-in-laws truck.
It's a 2009 F350ccsb 4x4.
It has a DPF delete, AFE air filter, and a H&S Black Max tuner, which is always set on the hot tune.
We took it to the dealership, and the tech used a stethescope to see if he could pin point the issue, but could not.
He hooked up a laptop, and plugged into the OBDII connector, and said "this is a cheap way to do a compression test". (Not sure what he did.)

It runs smooth, no smoke at idle...no miss.
Tech said it had good compression.
Truck has 145000 kilometers. (~80k miles)

I thought it might be rocker arm, or pushrod.
Tech said it might be a lifter.

It follows the engine rpm.

Any ideas from people who have heard this noise, or suggestions of what it might be?

http://vid1141.photobucket.com/albums/n581/ExtendedPower/Mobile Uploads/20150720_143622.mp4

 

[DWhite]

All lifters I heard are more of a thump. To me it sounds like a worn rocker arm. Mine was making a faint sound like that and was worn rocker arms.

 

[Highroller54]

My guess is lifter.

 

[Extended Power]

The shop said he was looking at at least a 30 hour job, plus parts.
Tear into it until they find the problem.

Could this be a cracked piston?

 

[Extended Power]

My guess is lifter.

Collapsed lifter would be alright...but a broken needle bearing on the roller would suck.

He drove it about 5 hours at highway speed with it like that.

 

[Highroller54]

Well if it is a lifter making that noise my guess is the problem is on the roller side of it. lol.

 

[Extended Power]

I hope it's the lifter side of it, and maybe the sound is the pushrod clapping inside the lifter cup.....or the lifter being collapsed completely...

Anyways....it sounds like its a tear down, no matter what.
I told him that if he was to trade it in for a new truck, they would just take the truck...basically steal it from him for what they would give to him as a trade...even though the truck looks brand new yet. (He is 76yrs old, and doesn't drive it hard at all.)

 

[Highroller54]

I would just tear it down find the problem and fix it, but then again I love my 6.4 and I don't pay labour and get parts at cost lol.

 

[Extended Power]

Yeah...my father-in-law does not go into much more than, intake, exhaust and air filter....anything else, and a shop usually does it...which is fine when it's a small job...but this is looking like a $5000.00 plus parts job if he takes it back to the shop for repair.

I said I could do it, but don't expect it back for awhile...