Excessive Amount of Smoke on Startup

[stebo]

I have a 2019 with the 5.7L and 143K miles. Over the years, I have seen occasional puffs of blue smoke on startup. Nothing too crazy. However, the last three mornings on initial startup after sitting all night, I have had excessive amounts of blue smoke from both tail pipes. See attached photos. It clears up after a few seconds and no smoke while driving. I'm assuming valve seals? Just odd how it pretty much happened overnight. Am I correct in assuming valve seals or is there something more serious going on here?

 

[HemiDude]

I have a 2019 with the 5.7L and 143K miles. Over the years, I have seen occasional puffs of blue smoke on startup. Nothing too crazy. However, the last three mornings on initial startup after sitting all night, I have had excessive amounts of blue smoke from both tail pipes. See attached photos. It clears up after a few seconds and no smoke while driving. I'm assuming valve seals? Just odd how it pretty much happened overnight. Am I correct in assuming valve seals or is there something more serious going on here?

Any chance someone overfilled the oil? Any noise on startup, like piston slap?

 

[John Kloehr]

Give the smoke a sniff. Oily or steamy?

If oily, then possibly valve seals or stems (or overfilled oil).

If steamy, might just be a weather change. One of the by-products of catalytic converters is water. Some water may be condensing and accumulating after engine shutdown, then becoming visible steam on the next startup until the converters "flash off" and return to making gas water vapor. As the temperature and humidity change, the problem may disappear until next time.

 

[stebo]

Any chance someone overfilled the oil? Any noise on startup, like piston slap?

It's been 5K miles since I changed the oil and the oil level is perfect. No noise on startup either.

 

[stebo]

Give the smoke a sniff. Oily or steamy?

If oily, then possibly valve seals or stems (or overfilled oil).

If steamy, might just be a weather change. One of the by-products of catalytic converters is water. Some water may be condensing and accumulating after engine shutdown, then becoming visible steam on the next startup until the converters "flash off" and return to making gas water vapor. As the temperature and humidity change, the problem may disappear until next time.

I'll check again tomorrow morning, but pretty sure it's an oily blue smoke. Definitely not normal, whatever is going on.

 

[BowDown]

Valve stem seals or the valve guides have excessive play. I vote valve stem seals, my 2003 5.7 did the same thing around 200K miles.
Pooled oil in the head is leaking past the valve stem seals. When the truck sits for long periods of time, the leaking oil pools in the cylinder and burns off when starting the engine. Plugs will likely be oily as well