Link Bar Lifter Failure

[skinny z]

I've finally got back to this engine and have started the teardown and post-mortem.
The history has been laid out here but the short story is a cam and head swap about 8000 miles ago (used cam and lifters and fresh heads). All was good until a misfire developed at high RPM. It was downhill from there.

This is what was under the intake.

IMG_20211003_131423043.jpg

I've personally never seen this before (Then again I'm just a hobbyist).
Those are COMPs short travel lifters. Purchased new in 2012. About 35 000 miles old.

It appears that other than the obvious and the cam itself, that nothing else has been caught up in this. Pushrods are straight. Valve tips look new. No broken springs (that I can see).
Since the time I reassembled the engine for a cam swap (used COMP XR288 as well as the used lifters) in 2016 it's seen about 8000 miles. Most of which have been in "limp" mode.

The link bar is nowhere to be seen...

EDIT: A ST search shows this isn't necessarily unique.
My best guess (at this point) is that I lost the thrust button on the cam and the excessive endplay let the roller drop off the lobe. The rest is stress.

[BillK]

My best guess (at this point) is that I lost the thrust button on the cam and the excessive end play let the roller drop off the lobe. The rest is stress.

I would think that if that happened it would have affected all of them ? If anything it would have allowed the lifter to hit the next lobe. not "drop down" Either way I suppose the end result is going to be ugly

[skinny z]

My best guess (at this point) is that I lost the thrust button on the cam and the excessive end play let the roller drop off the lobe. The rest is stress.

I would think that if that happened it would have affected all of them ? If anything it would have allowed the lifter to hit the next lobe. not "drop down" Either way I suppose the end result is going to be ugly

Yeah. I've thought the same thing. It's hard to say. If not the thrust button then it points to fatigue as the culprit. I've reached out to COMP for some kind of direction. Inspection? Trash? These parts aren't necessarily cheap.
I CAN say that I had found a fragment attached to the magnetic oil pan plug that was the first bit of evidence that something was going sideways. It saw very little running time after that. Moving from A to B for storage mostly. That was 2018.

Fragment 3.jpg

I'm just getting around to it now. COVID and the shitty economy in this part of the country set me back a couple of years in the hobby department.

[F-BIRD'88]

If the camshaft is not damaged,,, Here is a set of crane solid roller lifters . Put em in. Set the valve lash very tight.
.002"-.004". and go.. These won't break.
Can now take more valve spring for more rpm
and no lift loss from hyd leak down.
https://www.kijiji.ca/v-engines-and-eng ... 1557676741

[mag2555]

Why does everything look so dry in the lifter valley, did you spray it down?

[norm]

Wouldn't something have to cause that to break? Are the rollers still on the lifters even after turning sideways?

There can't be much load on the link bar normally, can't believe it's just the link bar that broke causing the issue. Lifter stick in the bore?

[tjs44]

is it a weird pic or are there some witness marks on the buttons holding the link bars.I see shiny spots on the 2 on the far right?Tom

[tjs44]

maybe oil droplets?Tom

[allencr267]

Hydraulic, plain bearings, not that it would matter?
Any wear on the other links look excessive?
That link is almost friction-less at low revs & wouldn't have mush stress at high revs from trying to rotate unless the lobe or roller or lifter bore is off.
How are those buttons retaining the link staked on?

Good luck.

[6.50camaro]

Hard to tell in the photo put it almost looks like the button under the link bar in the pic pulled out (not staked in proper) and the other button failed as the first button started to work its way out of the lifter . Dan

[mag2555]

Is it me, or do some of the marks on those buttons look like the lifters had been installed the wrong way?

And if so what could that type of loading done to the retention fit of those buttons?

[midnightbluS10]

Is it me, or do some of the marks on those buttons look like the lifters had been installed the wrong way?

And if so what could that type of loading done to the retention fit of those buttons?

I think it's just you. Those pics aren't high definition enough to make any sort of determination about what, caused the failure. You're just guessing going by crappy pics on the internet.

[skinny z]

If the camshaft is not damaged,,, Here is a set of crane solid roller lifters . Put em in. Set the valve lash very tight.
.002"-.004". and go.. These won't break.
Can now take more valve spring for more rpm
and no lift loss from hyd leak down.
https://www.kijiji.ca/v-engines-and-eng ... 1557676741

The cam is done. And I'd say the other lifters are doomed as well.

[skinny z]

Why does everything look so dry in the lifter valley, did you spray it down?

Pretty much yeah. Plenty of rust inhibitor on the cast iron. I can't say I cared too much about crap getting inside. Bits of intake gasket and other trash got in. It'll all soon be apart and cleaned or in the trash bin.

[skinny z]

Wouldn't something have to cause that to break? Are the rollers still on the lifters even after turning sideways?

There can't be much load on the link bar normally, can't believe it's just the link bar that broke causing the issue. Lifter stick in the bore?

At this point I'll say fatigue. The lifters are 35 000 miles old. Lots of RPM. Lots of track time. All it takes is one rivet...
All of the wear marks on the black oxide look to be the same and uniform and all of the lifter bodies. Even the broken set. I don't think the damage was long lived. Nor did it see any RPM I was aware that something was wounded. But prior to any indication that something was going sideways (figuratively and literally), I leaned on it pretty hard. 6500 shifts. 7000 rev limiter. Nothing that we haven't done with exactly the same collection of parts, Just newer.