Someone Installed a Head Gasket Upside Down on This Small Block V-8

GM’s 6.2-liter L87 small-block V-8 is subject to a huge recall over bad crankshafts and/or connecting rods in engines built between 2021 and 2024. This earlier L87 V-8, from a 2019 GMC Sierra Denali, is destroyed for an entirely different reason—likely human error. 

The always-entertaining I Do Cars on YouTube tears down an L87 in this video. This example has less than 50,000 miles, and the car it came from had a good service history. But it doesn’t take much unbolting to reveal an engine with catastrophic damage. And it appears the problem isn’t GM’s fault. For whatever reason, the truck had a lot of work done to at the dealer it before customer delivery, and as a commenter who claims to be a GM mechanic points out, the driver’s side head gasket was installed upside down.

It’s unclear how long the engine ran with its upside-down head gasket, but run it did, until it inevitably overheated. The commenter says that the improperly installed gasket blocks the coolant passages to the head, which severely limits cooling and will result in failure. Which is why the driver’s-side head looks so terrible, especially compared to the passenger-side head, and even with frequent oil changes. 

There’s all sorts of carnage deeper in the engine. Two of the connecting rods got extremely hot, and likely locked up the engine, causing the destruction we see here. 

What’s funny is that there’s even the word “FRONT” stamped into the head gasket to prevent exactly this sort of thing from happening. But, you truly can’t make everything foolproof.