[Watch] Mechanic shows the inside of a failed 1,000-mile GM L87 engine
The pulled unit is an L87 V8. It’s one of the 877,000 GM engines included in the NHTSA’s probe into early failure. Case in point: David Bell’s shop yanked this one out of a brand-new Cadillac Escalade. GM says that the connecting rod bearings keep failing…but after Bell took one apart, he’s not seeing bearing failure.
“This thing ate a rod.”
…”Snapped it right off.” Bell holds up two pieces of the same piston rod. Next, he shows another piston. It’s damaged from that broken rod hitting it.
Strangely, though, there’s no sign of rod bearing trouble. He spots a separate issue.
Expert mechanic suspects a GM L87 engine piston casting issue
Bell notices a piston missing a C clip. These clips serve as retainers, keeping the wrist pin in place. They allow for proper rotational piston movement while preventing axial movement. If they come out of place, the wrist pin will go off-kilter. A cascade of internal failures results, including broken piston rods and damaged pistons.
Oddly, it seems to Bell that the casting on the piston is boogered up to the point when a C clip could have trouble staying installed.
The expert says that when GM warranties these engines, its service departments tend not to let the company mechanics take the time to tear them down and look inside. Instead, they simply remove and replace the whole unit.
While GM states rod bearing failure as the main culprit, Bell shows a rod bearing. It looks undamaged. Now, GM’s formal April 2025 L87 recall does include more general language: “The connecting rod and/or crankshaft engine components in these vehicles may have manufacturing defects that can lead to engine damage and engine failure.”
So why does Bell’s shop have a failed GM L87 engine when surely an Escalade with less than 1,000 miles on it is covered under factory warranty? A few followers say that his shop rebuilds engine cores. In any case, if you’ve got one, this video gives you an idea of what’s going on inside.
