A teardown of a high-mileage Chevrolet Silverado engine has revealed extensive internal damage, but the evidence suggests the failure may have involved previous modifications or repairs rather than being solely attributable to the engine’s original design.
The Engine Behind the Silverado Teardown
The all-new 2027 Chevrolet Silverado is set to receive two new engines from General Motors’ Gen 6 small-block V8 family. Before those engines arrived, the 6.2-liter L87 was associated with a major recall and lawsuits involving crankshaft, connecting-rod and bearing failures.
The L87 followed the L86, an engine closely related to the C7 Corvette’s LT1 but adapted for truck applications. Eric from I Do Cars recently examined a specific L86 removed from a 2014 Chevy Silverado High Country after discovering large holes in its engine block.
A 200,000-Mile Silverado With Six Owners
After reviewing the vehicle’s Carfax history, Eric found that the donor Silverado had been owned by six different people, all in South Carolina. The truck had accumulated more than 200,000 miles, leaving open the possibility that neglect by one or more previous owners contributed to the engine failure.
The teardown showed that most of the components in the cylinder heads remained in reasonably good condition, particularly given the engine’s mileage. But removing the left-hand cylinder head exposed significant internal damage.
One piston crown had been destroyed, with connecting-rod-bearing debris sitting on top of it. The inspection also uncovered a destroyed connecting rod, a missing wrist pin and damage to the cylinder walls.
The Damage Did Not Clearly Point to Oil Starvation
Despite the severity of the failure, the engine did not display obvious widespread evidence of oil starvation. There were no clear signs such as overheating or discoloration throughout the rotating assembly that would readily explain the catastrophic damage.
Instead, Eric discovered evidence that the engine had previously been modified. The Active Fuel Management system had been deleted, while an aftermarket BTR camshaft had been installed.
AFM is commonly removed to avoid potential problems with its specialized lifters, although doing so comes with slightly higher fuel consumption.
One connecting rod also appeared to have been replaced. Its noticeably different discoloration compared with the other rods suggested that someone had previously worked on the L86.
Previous Repairs Could Have Played a Role
The evidence led Eric to conclude that the engine was likely rebuilt at some point. If so, incorrectly sized components or improper assembly could not be ruled out as possible contributors to the failure.
The mechanic suspected that the engine may previously have dropped an intake valve or experienced a similar high-RPM mechanical failure that damaged the rotating assembly.
What the Teardown Revealed
If that theory is correct, General Motors may not deserve all the blame for this particular engine failure. Instead, the teardown underscores how previous repairs, improper parts or assembly practices and cost-cutting can affect the outcome of a high-mileage engine.
The heavily damaged L86 from the 2014 Chevrolet Silverado High Country ultimately showed signs that its history involved more than simple wear, with evidence of earlier modifications and possible repairs complicating the cause of its failure.
