Brand new Yamaha 250 4 stroke failure

[rodbolt17]

Yamaha is very good about warrenty repairs.
did an F350 last week that the head failed to drain and it froze and cracked causing saltwater intrusion.
Yamaha sent 2 heads and a block assy and paid the labor.

[99yam40]

why did it not drain?
Yamaha took it as a design flaw or part failure?

[boscoe99]

My sources inform me that it is not a draining issue. Some exhaust manifolds were simply incorrectly cast at the factory. Yamaha has/had no idea which ones so they could not do a recall, even if they wanted to.

Cracked exhaust manifolds have been reported from Miami, the Florida keys, and the Caribbean where freezing is not an issue.

Note that the exhaust manifold part number has not changed over time. It is the same part number and same design. Better quality control has resulted in later production exhaust manifolds being less prone to cracking.

The very first exhaust manifold part number is still available from Yamaha. Just now a better product from a production standpoint.

Later F350's now come with the exhaust manifold integral with the cylinder head.

[rodbolt17]

this was the actual cyl head.
cracked about 3 inchs just below #5 spark plug.
failed to drain. we winterized it and this spring surprise.
done a few failed manifolds and way to many failed rotors.
typically a failed rotor makes a general nasty mess and breaks the crank just below #1 rod.