One of the scariest moments for any vehicle owner is when their engine begins making weird noises. Lately, a few GM V8s have been making several different noises, including chirps, squeaks or sputters, concerning many owners. Now, an article on GM TechLink says these noises are normal.
There are four common sounds produced by the affected engines:
- Catalyst light off – occurs on start, where spark timing is retarded for rapid catalyst converter warm-up, and may last roughly 30 seconds. Notably, this warm-up sequence is not triggered on all start-ups, as the vehicle must have sat for an hour or longer.
- Engine restart – following complete engine shutdown coasting down to 14 mph, spark timing is retarded to prevent engine overspeed/torque bump. This noise lasts only abut a second.
- Auto-start – at the end of an engine stop/start shutdown, spark timing is retarded to prevent engine overspeed/torque bump. This noise lasts only abut a second.
- Throttle blip – a light blip of the throttle while in park/neutral results in spark timing being reduced to prevent engine overspeed. This sound is hardly noticeable and hard to reproduce.
The 6.2L V8 L87 gasoline engine and the 6.6L V8 L8T gasoline engine are known to produce these peculiar noises under various conditions. These engines are found in some 2019-2023 Chevy Silverado 1500, Silverado HD, Chevy Tahoe, Chevy Suburban, GMC Sierra 1500, GMC Sierra HD, GMC Yukon and Cadillac Escalade models. Notably, these sounds are much more noticeable in the L87 and L8T engines than in the 5.3L V8 L84 gasoline engine.
It’s worth noting that comparing these noises to other, similar vehicles is not recommended, as the noises may be different from one vehicle to another. This could result in unnecessary repairs, as the sounds are a normal characteristic of a healthy, operating engine. Replacing the engine or internal components in an attempt to fix the sounds will not reduce or eliminate them.