F225 Corrosion

[max366]

My 2004 F225s had bad dry exhaust stack corrosion- the Yam repair shop said worst they have seen. 390 hours. The port engine also had water in 2 cylinders that froze open the valves and lots of salt corrosion, so I needed a new powerhead. Lots of water in the oil. I'm trying to figure out how the water got into the oil. The mechanic said it went past the rings, while someone else said it was the result of the corrosion of the oil pan which allowed water into the oil. I don't see the pathway for the water into the oil- the pan has corrosion but not where there's water.

Can someone tell me about what's in the two ports that pass through the oil pan? I think the back one, with 2 bolts holes, is the cold water feed to the block, but how about the one that's adjacent to the exhaust manifold? It's towards the stern on the exhaust manifold and rectangular in shape, where the manifold port is square. Can't post a pic of it unfortunately.

 

[GW96]

You're gonna get way more info on this over at The Hull Truth. There are A LOT of threads on the F225 corrosion there, many with pictures and in depth tear down explanations, not to mention a lot of Yami experts on that site. You'll find every answer there, probably without even posting, just searching will yield pages on the F225 corrosion issue.

 

[max366]

Thanks- You're right about THT but I find the quality of responses on this site are dramatically higher, so I thought I'd try here. There are so many armchairs "experts" there, it's hard to get straight info.
I did talk with a Yamaha tech and found the info I needed, but also learned that salt water does indeed get into the "dry" stack exhaust area, below the oil pan. The water leaving the block passes down separate isolated passageways on both sides of the pan, and is then sent inside the muffler where it mixes with exhaust gas.
Many responders on THT say that flushing doesn't matter in helping mitigate the corrosion issue, but this is plainly incorrect. So if you have an F225 (the tech said even model year 2006 engines are seeing corrosion) you might consider flushing. He also said they attribute it to incorrect prop, meaning the engine has to work harder, resulting in hotter exhaust gas.
Another tip is the position of the thermostat- be sure the copper support "arms" are not positioned horizontally, where they can contact the block, causing the aluminum to corrode. Rotate them 90 degrees. This might only apply to 2004 models, but worth checking other years.

 

[swede]

Is it an issue with freshwater engines?

 

[max366]

The Yam tech said they have not seen any FW engines affected by this problem.

 

[dale1]

greetings. I just rebuilt both of mine. 2002s. with 600 hours. one motor was much more corroded than the other? see the post "tail of two motors"

I don't remember about the ports. I do remember seeing carrion on the water or exhaust side of the oil pan though.

I was baffled by how one motor would corroded more than the other. same boat, same servicing/flushing, same age/hours?

thank goodness, I did not have any corrosion on the power heads. so my repair was around 2 grand for both.

dale