LS3: Two rockers have failed after new lifters & cam - any ideas?

[skip100]

2017 V8 Caprice
After having all lifters & cam replaced, two rocker arms have failed, one shortly after the other. Mechanic is going to install a trunion upgrade kit.
Just after the lifters & cam were done, it was running very quietly - even when stone cold.
Is it possible something was done incorrectly to cause this problem?
Btw, this is the second time the head has been off - first time was circa 100K ago, when *only* the lifters were replaced.
Note also: a high flow oil pump was fitted this second time. (he wants to increase oil pressure at low revs)

[Toddler78]

How have they failed?

[skip100]

I'll have to ask so I can answer properly, but I do know that he said something has "completely fallen out" (the bearing, or part of the bearing, I think) and is missing, which means it's in the sump. He said we can just risk it and leave it there, or remove the sump - I've chosen not to risk it. I think the first one was just loose.
Is it possible too much material has been removed from the head, when they machine the head?

[Micks]

I'll have to ask so I can answer properly, but I do know that he said something has "completely fallen out" (the bearing, or part of the bearing, I think) and is missing, which means it's in the sump. He said we can just risk it and leave it there, or remove the sump - I've chosen not to risk it. I think the first one was just loose.
Is it possible too much material has been removed from the head, when they machine the head?

Yes the needle rollers have let go, how many K's on this LS3?

[skip100]

240,000km.

[Micks]

240,000km.

Shame they were overlooked when previous work was done! A bronze bush trunnion upgrade is cheap insurance to prevent a hundred needle rollers falling in your engine.

[skip100]

Thanks. The reason they were probably "overlooked" is because the mechanic has never, ever, had a failed rocker on a Hire Car. (and this mechanic rebuilds these engines for hire cars frequently - he has a very good reputation in our community)
I told him that on one occasion a few months ago, the engine did seem to do something strange - it sort of "locked up" at a high RPM - I remember having to back off the throttle in order to release it from this condition. He said it may have experienced an over-rev situation, and that may have damaged the rockers. Said it can happen due to a transmission fault, or even a software bug.

[skip100]

Trunion upgrade has been installed. Many (19) of the remaining 30 rocker bearings were worn - "they fell straight out". Engine is nice and quiet again, even when stone cold. He now thinks it was just normal wear, because it's too consistent - no longer suspects a high revving incident.
Let's see how many days it lasts this time.