My 2008 Toyota Tundra makes a ticking sound from the 5.8L V8 at start up. This noise is much more predominant at start up in cold weather, but eventually gets almost unnoticeable after the engine is warm. Dealer explained to me that this is normal on some forged piston toyota engines and a result of expansion of the piston. This sound has been present since the truck was brand new. 7000 miles left on the original warranty. Is this statement on forged pistons correct or should I seek a second opinion from another Toyota Dealer?
Sounds more like a bad bearing, try the tom and ray method of locating the noise, and get it fixed under warranty.
Ticking noises when cold are ususally a sign of excessive clearance caused by leaking valve guide seals. However, at this low age that seems unusual.
The story of the forged pistons COULD be true, but I don’t know enough about your engine to confirm that.
Since the waranty is about to run out, I would get another dealer’s opinion, or an expert independent mechanic. Don’t believe what dealers tell you without confirmation from another source.
What the dealer is describing is called piston slap. This happens when pistons aren’t perfectly sized to the cylinder bores.
When the engine and pistons are cold and the engine is started, the pistons will slightly rock on the connecting rods as they move up the cylinder bores. This rocking action causes the piston skirts to slap the cylinder walls on it’s way up and you get the ticking noise. As the pistons expand from heat, it allows the pistons to move up the cylinder bores without rocking on the connecting rods so the skirt of the piston no longer slaps the the cylinder wall and the piston slap stops.
Piston slap isn’t harmful to an engine. It’s more of a embarrassement to have an engine make this kind of noise in a new vehicle.