What does this mean?
 

Flushing the motors with antifreeze yesterday and had a strong smell of formaldehyde. Is this worrisome?

odor
 

If it was in salt water and you pulled the boat and it sat for a while thats the smell of the stagnated salt water.JOHN

Back from the dead?

Thats what I was thinking................... :)

if your manifolds got too hot, could be vapor from the ethylene glycol or anti corrosion compounds

Boy That Stinks.

You might have started to burn up an Acetal bearing, washer or shim. I have no idea where one might be in the system. I forget what polymer the housings are made from. Acetal is a self lubricating plastic and when burned or degraded it gives off formaldehyde.

im curious how you know what formaldehyde smells like. :)

Smelled like himself??

Maybe a little birdy got sucked up in to the flamearrestor and died in the engine ???????????:rolleyes::D