GM’s small-block LS-based V8 engines are among the most widespread and popular V8 engines to exist. They power numerous vehicles from the American brand, from trusty staples like the Chevrolet Silverado and GMC Yukon to other trucks, SUVs, and of course, the Corvette. This I Do Cars video focuses on the L92 all-aluminum engine first launched in 2007, not to be confused with the L87 6.2-liter V8 currently the subject of all kinds of controversy.
The older V8 is largely a dependable workhorse, but even the most dependable workhorses have limits. In this case, an L92 from a 268,000‑mile 2009 Yukon Denali had a catastrophic failure and we do mean catastrophic. The engine had holes in the block, but a closer look through a painstakingly long teardown process (video at the bottom) gave us the full story of what exactly killed the reliable power plant.
Gruesome Internals Tell The Tale
Piece by piece through the teardown, the dead L92 V8 looked as if it had gone through a beating. It had a cracked oil pan, a vaporized piston, a rod folded back on itself, and metallic shrapnel peppered the sump and oil pump. The most gruesome part was the combustion chamber, which had been caked with carbon. But ultimately, the biggest culprit was a lone fragment of valve seat steel that lay in the wreckage.
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That shard told the tale: the intake valve seat in the rectangle‑port head had come loose, wedged the valve open, and let the piston smash it. The resulting debris cascade destroyed the rotating assembly, scoured the cylinder wall, and ultimately punched through the block. It was catastrophic, but as I Do Cars noted, it was also preventable.
Reliable, But Not Immune To Neglect
The L92 V8’s reliability isn’t a myth. With the absence of the cylinder deactivation feature (introduced in later versions), the engine didn’t have many naysayers. Car Complaints list a total of 136 owner grievances for the 2009 GMC Yukon – but only eight involve the engine, and just four cite outright “engine dies while driving” instances. Interior trim and dash cracks are far more common concerns for owners, which stains the model year’s name in terms of overall reliability. Considering General Motors built millions of these engines over the course of several years, that’s not a bad track record at all.
That said, dropped valve seats on LS‑family rectangle‑port heads almost always trace back to chronic overheating. That’s because aluminum heads expand faster than the press‑fit steel seats. If things get too warm, that seat could work loose and lead to all kinds of havoc. Admittedly, seeing this much damage from a dropped seat is a bit surprising.
Keeping an L92 alive therefore starts with a simple discipline: flush the cooling system often, replace deteriorated radiator caps and hoses, and make sure the electric fans cycle on at the right temperature. Ignoring the warning signs, like the owner of the dead engine here, could result in an engine that bombs itself.
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