Engine rattling/ticking noise

[Ficm]

I've got a 6.4L that makes rattling/ticking engine noise when tipping in on acceleration or  when free revving engine mostly audible coming off throttle. No codes, Relative compression 1% down on 2 all others zero. Fuel trim +12 cylinder 2 with no drivability issues.

 

It's is a fleet truck with dump box, lots of short trips and idling . The noise sounds like valve train, is it a matter of concern at this point and what have been your findings?

 

I've heard about rocker arm tips failing, could this possibly be a tell tale?

 

Thank you for your input.

[Keith Browning]

+12 STFT is a wee bit too high. You might want to remove the bank 2 valve cover and inspect the valvetrain - pay close attention to the rocker arm tips which can show accelerated wear, seizing, missing tips and valve bridges that pop off as a result...

[8WA Sman]

Does it go away when you kill any of the injectors?

[Matt Saunoras]

You may have multiple worn rocker arms causing the noise but the STFT shows something of some concern. It's possible it's one single rocker arm but I'd be suspicious, I have seen lots of #2 cylinder walls washed out.  Well not lots, but more than you can count on both hands. If absolutely nothing shows up base engine related I have swapped injectors to find the miss follows. 

[mchan68]

The last one I had with exactly that noise described ended up having a failed horizontal cooler and an 'S' shaped cylinder #8 connecting rod.

[Ficm]

mchan68, did the failed horizontal cooler cause a hydrolock? Do you bench test EGR coolers to verify failure or is there another way?

[Ficm]

8WA Sman I have not tried cancelling injectors, will check it out.

[mchan68]

The horizontal cooler was completely drenched in coolant. The vertical cooler tested out good, on the bench.

[Aaron]

My truck has been making that noise for 2+ years and 60,000+ Kms. No issues at this point. I'm thinking rocker arms, but haven't had the time, energy, or money to look.