Yamaha water jacket corrosion

[Levi smith]

Pulled the heads to clean my water jackets because of an over heating alarm and found this corrosion up at the top. Should this affect anything and is this okay to put back together and run? If not anyone know what I should do or what my options are? Motor is a 2004 200ox66. Thanks in advance View attachment IMG_4496.jpeg

 

[racerone]

That appears in more than 1 Yamaha product.-----Got a 2005 model 90 for free from a dealer , motor was declared scrap due to water jacket corrosion.----And not from salt water either.

 

[99yam40]

looks like plenty of meat left on all sealing surfaces to me.
I would remove as much build up to make sure cooling passages are clear and put it back together with new gaskets

 

[racerone]

Just a matter of time as severe corrosion is happening.----Material will fall off around the cast iron cylinders.