Blown 4.2 SHO, Offshore What is Failing?

[FOURCED]

Hopefully the Majority of the failures are behind us and related to the thrust bearing issues, gas in oil, making oil, uneducated / unaware owners but still - Where is the discussion of what exactly is failing?

I realize that an autopsy of a power head with a ventilated block is not the easiest thing to do or decipher in terms of which came first, but its not rocket science and I'm sure someone can do it or has done it and surely there should be a recommendation as to what we Should and Should Not be doing with these things.

I realize that most of us are Fishermen and not Serious Mechanics but If there is a thread or discussion somewhere please point me to it so I can learn and not waste anyone's time here.

Thanks!

[bandit53]

Anytime Yamaha replaces a blown powerhead, the original must be returned to Yamaha for analysis. There will certainly be opinions floated around on this and other forums, but those are just that, opinions and come from a small sample base. Unfortunately, I have not seen anything posted by Yamaha, only instructions and recommendations on how to break-in and operate, which normally come through a dealer.

[yam911]

Failure analysis is tough. Really tough.

In the airline industry they spend millions of dollars trying to determine what caused a particular failure. At the end of most investigations they come up with a "probable" cause. Probable meaning a good guess. Most times they never know for sure.

In the marine industry there is neither the time nor the budget to spend analyzing most engine failures. Parts get replaced and they move on. Certainly if the same part fails over and over again (thrust bearings for instance) there are attempts to make it better. Four strokes before the SHO models used four piece thrust bearings. The SHO originally used a two piece thrust bearing. The bearings were failing. Simple fix was to then go back to the four piece thrust bearing. Along the way, material changes were made to the bearing to try and make it last longer.

[D-wayne]

Biggest difference between the other motors are the SHO is the lazer etched cylinders which are hard as... making it difficult for the rings to seat properly. Hense the "making oil" issue.
Secondly is the way the engines are operated.
Start up , 5 seconds, full throttle, 5 minutes, slow down , 30 seconds, idle 10 seconds, shut down, cool off totally, repeat.
No one drives their car like that because it is too hard on things and yet we expect to be able to have an outboard motor last and last with that abuse.
Just something to think about

[CJ1]

Biggest difference between the other motors are the SHO is the lazer etched cylinders which are hard as... making it difficult for the rings to seat properly. Hense the "making oil" issue.
Secondly is the way the engines are operated.
Start up , 5 seconds, full throttle, 5 minutes, slow down , 30 seconds, idle 10 seconds, shut down, cool off totally, repeat.
No one drives their car like that because it is too hard on things and yet we expect to be able to have an outboard motor last and last with that abuse.
Just something to think about

AND, with old fuel that was probably right at the octane lower limit 1 year ago, with ethanol gathering moisture because of leaving the tank almost empty over countless temp swings sitting in a non temp controlled environment. THEN changing the engine oil at the start of the season vs. the end to get all the built up acids out of the crankcase because the engine never warms up completely because of the reasons you mentioned AND stats that open at 140 degrees. Filters? what filters? it still runs, no problem! Then complain when it blows up. Sorry but I had to! One quick story. Got a call on a twin engine boat. Would not run. I get there and looked at the fuel system first. [Only common item between 2 fuel injected engines] Uh water in everything. Pull the water out of the bottom of the tank, drain and clean filters and injection system pump the best I can standing on my head. [hate I/O boats]. Get 1 engine running and mess with the other one for 1/2 hour or so till I could get some Iso alcohol into it and running. So 3 hours later after running the boat and am satisfied it is good I talk to the owner. I see 6 5 gallon cans directly under the eve where all the rain water is running directly on them. Yup, you bet trying to save a few $$ on a 70k boat by hauling gas to it everyday vs spending $100 more at the marina. I understand this but???? really. Most boat engines live a truly neglected, harsh life. CJ