What could cause this bent push rod (not a Mopar, but still…)

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chrismalish

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Not not a Mopar, but a general engine question. Posting here because of the wealth of collective knowledge in general.

Last week wife was driving through the neighborhood collecting kids for carpool. 2018 suburban with 6.2 with 58,000 miles developed an engine noise/valve clatter. Truck gets intermittent usage, hence the relatively low miles.

Truck towed to dealer for warranty service. Valve clatter traced to bent push rod. Pictures below.

Tech reports no damage to lifters, rocker arms, or camshaft (camshaft inspected with camera while engine in car).

Service writer think this is just bad metallurgy and random failure; can’t find any other cause for damage (and they will get paid by the warranty company for anything that they can verify is broken and needs to be replaced).

I am worried that this problem may replicate itself again in a year or whatever, after the warranty has expired.

Thanks in advance for sharing your thoughts.

Chris

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Not familiar with those engines, what lubricates the valve stems? Did the dealer FOR SURE examine the valve and stem?
 
In my experience pushrods don't bend like that for the heck of it. It was placed in-between a rock and a had place

Like the valve was open at the wrong time and the piston hit it. (Timing chain, stuck lifter in the up position, valve stuck closed and the cam and lifter tried to open it)

I guess a lifter could have pumped up

But most of those should show damage to the piston top and the valve.

A pressure test on that cyl will show a bent valve.

I had a Ford 289 loose a timing chain at 2000 rpm. Lots of bent valves and pushrods.

If it's under warrantee I would get a second opinion from a qualified shop.

It concerns me that the parts are laid out relatively haphazardly, don't the lifters need to back into their respective bores?
 
I ain't buyin it. Something had to go solid for that to happen. Piston hit a valve, valve spring coil bind, valve guide locked down on the stem, retainer to guide.....SOMETHING caused it. It didn't "just happen".
 
Super common. The 6.2 has lifters that collapse to deactivate the cylinders. Sometimes they stick collapsed and then the pushrods fall out and get beat up. The best advice is get a cam and lifters and tune to delete the whole system. It's nothing but problems from here on out.
 
Gm dealer tech over 20 yrs. It’s a bad lifter. It’s a known problem, we see it all the time.
 
406dart said:
Gm dealer tech over 20 yrs. It’s a bad lifter. It’s a known problem, we see it all the time.
Click to expand...
406Dart, what’s the repair? Just replacing that lifter? All the lifters in that bank? All in the engine? Or is anything else needed?

Thanks
 
They already pulled one head, do at least one bank of lifters. I suggest putting a non afm cam and lifters in and tuning the system to delete it. I just did it on my 6.2. Buy once, cry once.
 
Another possibility is old fuel gumming up the valve guide since this truck sits a lot.

Doubtful though

Agree it didn't "just happen" or bad metallurgy LOL, it wouldn't have made it this far

They say don't buy these cylinder dropping engines form any maker. Including Ram pickups.
 
As correctly stated above, it is a common issue, in the LS style engines & Hemis. Any lack of oil pressure for whatever reason & a lifter will collapse completely & the pushrod jumps where it doesn't belong.
Particular to the Chebby at least into the mid/late '00's was the fact that the 4WD's used a tiny spin-on filter to clear the frt diff assy, it was restrictive & You couldn't screw around on the maintainance, they would cause low pressure in a hurry.
My Bud just went through this on His wife's Durango, #6, so......the common consensus there is an oil pump replacement that bumps output after changing the damaged parts.
If You plan on keeping it, do what Scampin said, otherwise.......
 
drive it til it happens again. if it's out of warranty by then do as suggested and replace the cam and lifters for 'normal' type.
neil.
ps as the lifters are roller type they don't 'have' to go back in the same holes they came from, unlike flat tappet type..
 
You already have the head off, at the very least replace that bank..
 
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